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Update docs about autocall and remove manual copy of cmd-line flags....
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1 1 # -*- coding: utf-8 -*-
2 2 """Usage information for the main IPython applications.
3 3 """
4 4 #-----------------------------------------------------------------------------
5 5 # Copyright (C) 2008-2011 The IPython Development Team
6 6 # Copyright (C) 2001-2007 Fernando Perez. <fperez@colorado.edu>
7 7 #
8 8 # Distributed under the terms of the BSD License. The full license is in
9 9 # the file COPYING, distributed as part of this software.
10 10 #-----------------------------------------------------------------------------
11 11
12 12 import sys
13 13 from IPython.core import release
14 14
15 15 cl_usage = """\
16 16 =========
17 17 IPython
18 18 =========
19 19
20 20 Tools for Interactive Computing in Python
21 21 =========================================
22 22
23 23 A Python shell with automatic history (input and output), dynamic object
24 24 introspection, easier configuration, command completion, access to the
25 25 system shell and more. IPython can also be embedded in running programs.
26 26
27 27
28 28 Usage
29 29
30 30 ipython [subcommand] [options] [files]
31 31
32 32 If invoked with no options, it executes all the files listed in sequence
33 33 and exits, use -i to enter interactive mode after running the files. Files
34 34 ending in .py will be treated as normal Python, but files ending in .ipy
35 35 can contain special IPython syntax (magic commands, shell expansions, etc.)
36 36
37 37 Almost all configuration in IPython is available via the command-line. Do
38 38 `ipython --help-all` to see all available options. For persistent
39 39 configuration, look into your `ipython_config.py` configuration file for
40 40 details.
41 41
42 42 This file is typically installed in the `IPYTHON_DIR` directory, and there
43 43 is a separate configuration directory for each profile. The default profile
44 44 directory will be located in $IPYTHON_DIR/profile_default. For Linux users,
45 45 IPYTHON_DIR defaults to `$HOME/.config/ipython`, and for other Unix systems
46 46 to `$HOME/.ipython`. For Windows users, $HOME resolves to C:\\Documents
47 47 and Settings\\YourUserName in most instances.
48 48
49 49 To initialize a profile with the default configuration file, do::
50 50
51 51 $> ipython profile create
52 52
53 53 and start editing `IPYTHON_DIR/profile_default/ipython_config.py`
54 54
55 55 In IPython's documentation, we will refer to this directory as
56 56 `IPYTHON_DIR`, you can change its default location by creating an
57 57 environment variable with this name and setting it to the desired path.
58 58
59 59 For more information, see the manual available in HTML and PDF in your
60 60 installation, or online at http://ipython.org/documentation.html.
61 61 """
62 62
63 63 interactive_usage = """
64 64 IPython -- An enhanced Interactive Python
65 65 =========================================
66 66
67 67 IPython offers a combination of convenient shell features, special commands
68 68 and a history mechanism for both input (command history) and output (results
69 69 caching, similar to Mathematica). It is intended to be a fully compatible
70 70 replacement for the standard Python interpreter, while offering vastly
71 71 improved functionality and flexibility.
72 72
73 73 At your system command line, type 'ipython -h' to see the command line
74 74 options available. This document only describes interactive features.
75 75
76 76 MAIN FEATURES
77 77
78 78 * Access to the standard Python help. As of Python 2.1, a help system is
79 79 available with access to object docstrings and the Python manuals. Simply
80 80 type 'help' (no quotes) to access it.
81 81
82 82 * Magic commands: type %magic for information on the magic subsystem.
83 83
84 84 * System command aliases, via the %alias command or the configuration file(s).
85 85
86 86 * Dynamic object information:
87 87
88 88 Typing ?word or word? prints detailed information about an object. If
89 89 certain strings in the object are too long (docstrings, code, etc.) they get
90 90 snipped in the center for brevity.
91 91
92 92 Typing ??word or word?? gives access to the full information without
93 93 snipping long strings. Long strings are sent to the screen through the less
94 94 pager if longer than the screen, printed otherwise.
95 95
96 96 The ?/?? system gives access to the full source code for any object (if
97 97 available), shows function prototypes and other useful information.
98 98
99 99 If you just want to see an object's docstring, type '%pdoc object' (without
100 100 quotes, and without % if you have automagic on).
101 101
102 102 Both %pdoc and ?/?? give you access to documentation even on things which are
103 103 not explicitely defined. Try for example typing {}.get? or after import os,
104 104 type os.path.abspath??. The magic functions %pdef, %source and %file operate
105 105 similarly.
106 106
107 107 * Completion in the local namespace, by typing TAB at the prompt.
108 108
109 109 At any time, hitting tab will complete any available python commands or
110 110 variable names, and show you a list of the possible completions if there's
111 111 no unambiguous one. It will also complete filenames in the current directory.
112 112
113 113 This feature requires the readline and rlcomplete modules, so it won't work
114 114 if your Python lacks readline support (such as under Windows).
115 115
116 116 * Search previous command history in two ways (also requires readline):
117 117
118 118 - Start typing, and then use Ctrl-p (previous,up) and Ctrl-n (next,down) to
119 119 search through only the history items that match what you've typed so
120 120 far. If you use Ctrl-p/Ctrl-n at a blank prompt, they just behave like
121 121 normal arrow keys.
122 122
123 123 - Hit Ctrl-r: opens a search prompt. Begin typing and the system searches
124 124 your history for lines that match what you've typed so far, completing as
125 125 much as it can.
126 126
127 127 - %hist: search history by index (this does *not* require readline).
128 128
129 129 * Persistent command history across sessions.
130 130
131 131 * Logging of input with the ability to save and restore a working session.
132 132
133 133 * System escape with !. Typing !ls will run 'ls' in the current directory.
134 134
135 135 * The reload command does a 'deep' reload of a module: changes made to the
136 136 module since you imported will actually be available without having to exit.
137 137
138 138 * Verbose and colored exception traceback printouts. See the magic xmode and
139 139 xcolor functions for details (just type %magic).
140 140
141 141 * Input caching system:
142 142
143 143 IPython offers numbered prompts (In/Out) with input and output caching. All
144 144 input is saved and can be retrieved as variables (besides the usual arrow
145 145 key recall).
146 146
147 147 The following GLOBAL variables always exist (so don't overwrite them!):
148 148 _i: stores previous input.
149 149 _ii: next previous.
150 150 _iii: next-next previous.
151 151 _ih : a list of all input _ih[n] is the input from line n.
152 152
153 153 Additionally, global variables named _i<n> are dynamically created (<n>
154 154 being the prompt counter), such that _i<n> == _ih[<n>]
155 155
156 156 For example, what you typed at prompt 14 is available as _i14 and _ih[14].
157 157
158 158 You can create macros which contain multiple input lines from this history,
159 159 for later re-execution, with the %macro function.
160 160
161 161 The history function %hist allows you to see any part of your input history
162 162 by printing a range of the _i variables. Note that inputs which contain
163 163 magic functions (%) appear in the history with a prepended comment. This is
164 164 because they aren't really valid Python code, so you can't exec them.
165 165
166 166 * Output caching system:
167 167
168 168 For output that is returned from actions, a system similar to the input
169 169 cache exists but using _ instead of _i. Only actions that produce a result
170 170 (NOT assignments, for example) are cached. If you are familiar with
171 171 Mathematica, IPython's _ variables behave exactly like Mathematica's %
172 172 variables.
173 173
174 174 The following GLOBAL variables always exist (so don't overwrite them!):
175 175 _ (one underscore): previous output.
176 176 __ (two underscores): next previous.
177 177 ___ (three underscores): next-next previous.
178 178
179 179 Global variables named _<n> are dynamically created (<n> being the prompt
180 180 counter), such that the result of output <n> is always available as _<n>.
181 181
182 182 Finally, a global dictionary named _oh exists with entries for all lines
183 183 which generated output.
184 184
185 185 * Directory history:
186 186
187 187 Your history of visited directories is kept in the global list _dh, and the
188 188 magic %cd command can be used to go to any entry in that list.
189 189
190 190 * Auto-parentheses and auto-quotes (adapted from Nathan Gray's LazyPython)
191 191
192 192 1. Auto-parentheses
193 193 Callable objects (i.e. functions, methods, etc) can be invoked like
194 194 this (notice the commas between the arguments):
195 195 In [1]: callable_ob arg1, arg2, arg3
196 196 and the input will be translated to this:
197 197 ------> callable_ob(arg1, arg2, arg3)
198 This feature is off by default (in rare cases it can produce
199 undesirable side-effects), but you can activate it at the command-line
200 by starting IPython with `--autocall 1`, set it permanently in your
201 configuration file, or turn on at runtime with `%autocall 1`.
202
198 203 You can force auto-parentheses by using '/' as the first character
199 204 of a line. For example:
200 205 In [1]: /globals # becomes 'globals()'
201 206 Note that the '/' MUST be the first character on the line! This
202 207 won't work:
203 208 In [2]: print /globals # syntax error
204 209
205 210 In most cases the automatic algorithm should work, so you should
206 211 rarely need to explicitly invoke /. One notable exception is if you
207 212 are trying to call a function with a list of tuples as arguments (the
208 213 parenthesis will confuse IPython):
209 214 In [1]: zip (1,2,3),(4,5,6) # won't work
210 215 but this will work:
211 216 In [2]: /zip (1,2,3),(4,5,6)
212 217 ------> zip ((1,2,3),(4,5,6))
213 218 Out[2]= [(1, 4), (2, 5), (3, 6)]
214 219
215 220 IPython tells you that it has altered your command line by
216 221 displaying the new command line preceded by -->. e.g.:
217 222 In [18]: callable list
218 223 -------> callable (list)
219 224
220 225 2. Auto-Quoting
221 226 You can force auto-quoting of a function's arguments by using ',' as
222 227 the first character of a line. For example:
223 228 In [1]: ,my_function /home/me # becomes my_function("/home/me")
224 229
225 230 If you use ';' instead, the whole argument is quoted as a single
226 231 string (while ',' splits on whitespace):
227 232 In [2]: ,my_function a b c # becomes my_function("a","b","c")
228 233 In [3]: ;my_function a b c # becomes my_function("a b c")
229 234
230 235 Note that the ',' MUST be the first character on the line! This
231 236 won't work:
232 237 In [4]: x = ,my_function /home/me # syntax error
233 238 """
234 239
235 240 interactive_usage_min = """\
236 241 An enhanced console for Python.
237 242 Some of its features are:
238 243 - Readline support if the readline library is present.
239 244 - Tab completion in the local namespace.
240 245 - Logging of input, see command-line options.
241 246 - System shell escape via ! , eg !ls.
242 247 - Magic commands, starting with a % (like %ls, %pwd, %cd, etc.)
243 248 - Keeps track of locally defined variables via %who, %whos.
244 249 - Show object information with a ? eg ?x or x? (use ?? for more info).
245 250 """
246 251
247 252 quick_reference = r"""
248 253 IPython -- An enhanced Interactive Python - Quick Reference Card
249 254 ================================================================
250 255
251 256 obj?, obj?? : Get help, or more help for object (also works as
252 257 ?obj, ??obj).
253 258 ?foo.*abc* : List names in 'foo' containing 'abc' in them.
254 259 %magic : Information about IPython's 'magic' % functions.
255 260
256 261 Magic functions are prefixed by %, and typically take their arguments without
257 262 parentheses, quotes or even commas for convenience.
258 263
259 264 Example magic function calls:
260 265
261 266 %alias d ls -F : 'd' is now an alias for 'ls -F'
262 267 alias d ls -F : Works if 'alias' not a python name
263 268 alist = %alias : Get list of aliases to 'alist'
264 269 cd /usr/share : Obvious. cd -<tab> to choose from visited dirs.
265 270 %cd?? : See help AND source for magic %cd
266 271
267 272 System commands:
268 273
269 274 !cp a.txt b/ : System command escape, calls os.system()
270 275 cp a.txt b/ : after %rehashx, most system commands work without !
271 276 cp ${f}.txt $bar : Variable expansion in magics and system commands
272 277 files = !ls /usr : Capture sytem command output
273 278 files.s, files.l, files.n: "a b c", ['a','b','c'], 'a\nb\nc'
274 279
275 280 History:
276 281
277 282 _i, _ii, _iii : Previous, next previous, next next previous input
278 283 _i4, _ih[2:5] : Input history line 4, lines 2-4
279 284 exec _i81 : Execute input history line #81 again
280 285 %rep 81 : Edit input history line #81
281 286 _, __, ___ : previous, next previous, next next previous output
282 287 _dh : Directory history
283 288 _oh : Output history
284 289 %hist : Command history. '%hist -g foo' search history for 'foo'
285 290
286 291 Autocall:
287 292
288 f 1,2 : f(1,2)
293 f 1,2 : f(1,2) # Off by default, enable with %autocall magic.
289 294 /f 1,2 : f(1,2) (forced autoparen)
290 295 ,f 1 2 : f("1","2")
291 296 ;f 1 2 : f("1 2")
292 297
293 298 Remember: TAB completion works in many contexts, not just file names
294 299 or python names.
295 300
296 301 The following magic functions are currently available:
297 302
298 303 """
299 304
300 305 gui_reference = """\
301 306 ===============================
302 307 The graphical IPython console
303 308 ===============================
304 309
305 310 This console is designed to emulate the look, feel and workflow of a terminal
306 311 environment, while adding a number of enhancements that are simply not possible
307 312 in a real terminal, such as inline syntax highlighting, true multiline editing,
308 313 inline graphics and much more.
309 314
310 315 This quick reference document contains the basic information you'll need to
311 316 know to make the most efficient use of it. For the various command line
312 317 options available at startup, type ``ipython qtconsole --help`` at the command line.
313 318
314 319
315 320 Multiline editing
316 321 =================
317 322
318 323 The graphical console is capable of true multiline editing, but it also tries
319 324 to behave intuitively like a terminal when possible. If you are used to
320 325 IPyhton's old terminal behavior, you should find the transition painless, and
321 326 once you learn a few basic keybindings it will be a much more efficient
322 327 environment.
323 328
324 329 For single expressions or indented blocks, the console behaves almost like the
325 330 terminal IPython: single expressions are immediately evaluated, and indented
326 331 blocks are evaluated once a single blank line is entered::
327 332
328 333 In [1]: print "Hello IPython!" # Enter was pressed at the end of the line
329 334 Hello IPython!
330 335
331 336 In [2]: for i in range(10):
332 337 ...: print i,
333 338 ...:
334 339 0 1 2 3 4 5 6 7 8 9
335 340
336 341 If you want to enter more than one expression in a single input block
337 342 (something not possible in the terminal), you can use ``Control-Enter`` at the
338 343 end of your first line instead of ``Enter``. At that point the console goes
339 344 into 'cell mode' and even if your inputs are not indented, it will continue
340 345 accepting arbitrarily many lines until either you enter an extra blank line or
341 346 you hit ``Shift-Enter`` (the key binding that forces execution). When a
342 347 multiline cell is entered, IPython analyzes it and executes its code producing
343 348 an ``Out[n]`` prompt only for the last expression in it, while the rest of the
344 349 cell is executed as if it was a script. An example should clarify this::
345 350
346 351 In [3]: x=1 # Hit C-Enter here
347 352 ...: y=2 # from now on, regular Enter is sufficient
348 353 ...: z=3
349 354 ...: x**2 # This does *not* produce an Out[] value
350 355 ...: x+y+z # Only the last expression does
351 356 ...:
352 357 Out[3]: 6
353 358
354 359 The behavior where an extra blank line forces execution is only active if you
355 360 are actually typing at the keyboard each line, and is meant to make it mimic
356 361 the IPython terminal behavior. If you paste a long chunk of input (for example
357 362 a long script copied form an editor or web browser), it can contain arbitrarily
358 363 many intermediate blank lines and they won't cause any problems. As always,
359 364 you can then make it execute by appending a blank line *at the end* or hitting
360 365 ``Shift-Enter`` anywhere within the cell.
361 366
362 367 With the up arrow key, you can retrieve previous blocks of input that contain
363 368 multiple lines. You can move inside of a multiline cell like you would in any
364 369 text editor. When you want it executed, the simplest thing to do is to hit the
365 370 force execution key, ``Shift-Enter`` (though you can also navigate to the end
366 371 and append a blank line by using ``Enter`` twice).
367 372
368 373 If you've edited a multiline cell and accidentally navigate out of it with the
369 374 up or down arrow keys, IPython will clear the cell and replace it with the
370 375 contents of the one above or below that you navigated to. If this was an
371 376 accident and you want to retrieve the cell you were editing, use the Undo
372 377 keybinding, ``Control-z``.
373 378
374 379
375 380 Key bindings
376 381 ============
377 382
378 383 The IPython console supports most of the basic Emacs line-oriented keybindings,
379 384 in addition to some of its own.
380 385
381 386 The keybinding prefixes mean:
382 387
383 388 - ``C``: Control
384 389 - ``S``: Shift
385 390 - ``M``: Meta (typically the Alt key)
386 391
387 392 The keybindings themselves are:
388 393
389 394 - ``Enter``: insert new line (may cause execution, see above).
390 395 - ``C-Enter``: *force* new line, *never* causes execution.
391 396 - ``S-Enter``: *force* execution regardless of where cursor is, no newline added.
392 397 - ``Up``: step backwards through the history.
393 398 - ``Down``: step forwards through the history.
394 399 - ``S-Up``: search backwards through the history (like ``C-r`` in bash).
395 400 - ``S-Down``: search forwards through the history.
396 401 - ``C-c``: copy highlighted text to clipboard (prompts are automatically stripped).
397 402 - ``C-S-c``: copy highlighted text to clipboard (prompts are not stripped).
398 403 - ``C-v``: paste text from clipboard.
399 404 - ``C-z``: undo (retrieves lost text if you move out of a cell with the arrows).
400 405 - ``C-S-z``: redo.
401 406 - ``C-o``: move to 'other' area, between pager and terminal.
402 407 - ``C-l``: clear terminal.
403 408 - ``C-a``: go to beginning of line.
404 409 - ``C-e``: go to end of line.
405 410 - ``C-k``: kill from cursor to the end of the line.
406 411 - ``C-y``: yank (paste)
407 412 - ``C-p``: previous line (like up arrow)
408 413 - ``C-n``: next line (like down arrow)
409 414 - ``C-f``: forward (like right arrow)
410 415 - ``C-b``: back (like left arrow)
411 416 - ``C-d``: delete next character.
412 417 - ``M-<``: move to the beginning of the input region.
413 418 - ``M->``: move to the end of the input region.
414 419 - ``M-d``: delete next word.
415 420 - ``M-Backspace``: delete previous word.
416 421 - ``C-.``: force a kernel restart (a confirmation dialog appears).
417 422 - ``C-+``: increase font size.
418 423 - ``C--``: decrease font size.
419 424 - ``C-M-Space``: toggle full screen. (Command-Control-Space on Mac OS X)
420 425
421 426 The IPython pager
422 427 =================
423 428
424 429 IPython will show long blocks of text from many sources using a builtin pager.
425 430 You can control where this pager appears with the ``--paging`` command-line
426 431 flag:
427 432
428 433 - ``inside`` [default]: the pager is overlaid on top of the main terminal. You
429 434 must quit the pager to get back to the terminal (similar to how a pager such
430 435 as ``less`` or ``more`` works).
431 436
432 437 - ``vsplit``: the console is made double-tall, and the pager appears on the
433 438 bottom area when needed. You can view its contents while using the terminal.
434 439
435 440 - ``hsplit``: the console is made double-wide, and the pager appears on the
436 441 right area when needed. You can view its contents while using the terminal.
437 442
438 443 - ``none``: the console never pages output.
439 444
440 445 If you use the vertical or horizontal paging modes, you can navigate between
441 446 terminal and pager as follows:
442 447
443 448 - Tab key: goes from pager to terminal (but not the other way around).
444 449 - Control-o: goes from one to another always.
445 450 - Mouse: click on either.
446 451
447 452 In all cases, the ``q`` or ``Escape`` keys quit the pager (when used with the
448 453 focus on the pager area).
449 454
450 455 Running subprocesses
451 456 ====================
452 457
453 458 The graphical IPython console uses the ``pexpect`` module to run subprocesses
454 459 when you type ``!command``. This has a number of advantages (true asynchronous
455 460 output from subprocesses as well as very robust termination of rogue
456 461 subprocesses with ``Control-C``), as well as some limitations. The main
457 462 limitation is that you can *not* interact back with the subprocess, so anything
458 463 that invokes a pager or expects you to type input into it will block and hang
459 464 (you can kill it with ``Control-C``).
460 465
461 466 We have provided as magics ``%less`` to page files (aliased to ``%more``),
462 467 ``%clear`` to clear the terminal, and ``%man`` on Linux/OSX. These cover the
463 468 most common commands you'd want to call in your subshell and that would cause
464 469 problems if invoked via ``!cmd``, but you need to be aware of this limitation.
465 470
466 471 Display
467 472 =======
468 473
469 474 The IPython console can now display objects in a variety of formats, including
470 475 HTML, PNG and SVG. This is accomplished using the display functions in
471 476 ``IPython.core.display``::
472 477
473 478 In [4]: from IPython.core.display import display, display_html
474 479
475 480 In [5]: from IPython.core.display import display_png, display_svg
476 481
477 482 Python objects can simply be passed to these functions and the appropriate
478 483 representations will be displayed in the console as long as the objects know
479 484 how to compute those representations. The easiest way of teaching objects how
480 485 to format themselves in various representations is to define special methods
481 486 such as: ``_repr_html_``, ``_repr_svg_`` and ``_repr_png_``. IPython's display formatters
482 487 can also be given custom formatter functions for various types::
483 488
484 489 In [6]: ip = get_ipython()
485 490
486 491 In [7]: html_formatter = ip.display_formatter.formatters['text/html']
487 492
488 493 In [8]: html_formatter.for_type(Foo, foo_to_html)
489 494
490 495 For further details, see ``IPython.core.formatters``.
491 496
492 497 Inline matplotlib graphics
493 498 ==========================
494 499
495 500 The IPython console is capable of displaying matplotlib figures inline, in SVG
496 501 or PNG format. If started with the ``pylab=inline``, then all figures are
497 502 rendered inline automatically (PNG by default). If started with ``--pylab``
498 503 or ``pylab=<your backend>``, then a GUI backend will be used, but IPython's
499 504 ``display()`` and ``getfigs()`` functions can be used to view plots inline::
500 505
501 506 In [9]: display(*getfigs()) # display all figures inline
502 507
503 508 In[10]: display(*getfigs(1,2)) # display figures 1 and 2 inline
504 509 """
505 510
506 511
507 512 quick_guide = """\
508 513 ? -> Introduction and overview of IPython's features.
509 514 %quickref -> Quick reference.
510 515 help -> Python's own help system.
511 516 object? -> Details about 'object', use 'object??' for extra details.
512 517 """
513 518
514 519 gui_note = """\
515 520 %guiref -> A brief reference about the graphical user interface.
516 521 """
517 522
518 523 default_banner_parts = [
519 524 'Python %s\n' % (sys.version.split('\n')[0],),
520 525 'Type "copyright", "credits" or "license" for more information.\n\n',
521 526 'IPython %s -- An enhanced Interactive Python.\n' % (release.version,),
522 527 quick_guide
523 528 ]
524 529
525 530 default_gui_banner_parts = default_banner_parts + [gui_note]
526 531
527 532 default_banner = ''.join(default_banner_parts)
528 533
529 534 default_gui_banner = ''.join(default_gui_banner_parts)
@@ -1,1263 +1,1003 b''
1 1 =================
2 2 IPython reference
3 3 =================
4 4
5 5 .. _command_line_options:
6 6
7 7 Command-line usage
8 8 ==================
9 9
10 10 You start IPython with the command::
11 11
12 12 $ ipython [options] files
13 13
14 14 .. note::
15 15
16 16 For IPython on Python 3, use ``ipython3`` in place of ``ipython``.
17 17
18 18 If invoked with no options, it executes all the files listed in sequence
19 19 and drops you into the interpreter while still acknowledging any options
20 20 you may have set in your ipython_config.py. This behavior is different from
21 21 standard Python, which when called as python -i will only execute one
22 22 file and ignore your configuration setup.
23 23
24 24 Please note that some of the configuration options are not available at
25 25 the command line, simply because they are not practical here. Look into
26 26 your configuration files for details on those. There are separate configuration
27 27 files for each profile, and the files look like "ipython_config.py" or
28 28 "ipython_config_<frontendname>.py". Profile directories look like
29 29 "profile_profilename" and are typically installed in the IPYTHON_DIR directory.
30 30 For Linux users, this will be $HOME/.config/ipython, and for other users it
31 31 will be $HOME/.ipython. For Windows users, $HOME resolves to C:\\Documents and
32 32 Settings\\YourUserName in most instances.
33 33
34 34
35 35 Eventloop integration
36 36 ---------------------
37 37
38 38 Previously IPython had command line options for controlling GUI event loop
39 39 integration (-gthread, -qthread, -q4thread, -wthread, -pylab). As of IPython
40 40 version 0.11, these have been removed. Please see the new ``%gui``
41 41 magic command or :ref:`this section <gui_support>` for details on the new
42 42 interface, or specify the gui at the commandline::
43 43
44 44 $ ipython --gui=qt
45 45
46 46
47 Regular Options
48 ---------------
47 Command-line Options
48 --------------------
49
50 To see the options IPython accepts, use ``ipython --help`` (and you probably
51 should run the output through a pager such as ``ipython --help | less`` for
52 more convenient reading). This shows all the options that have a single-word
53 alias to control them, but IPython lets you configure all of its objects from
54 the command-line by passing the full class name and a corresponding value; type
55 ``ipython --help-all`` to see this full list. For example::
56
57 ipython --pylab qt
58
59 is equivalent to::
60
61 ipython --TerminalIPythonApp.pylab='qt'
62
63 Note that in the second form, you *must* use the equal sign, as the expression
64 is evaluated as an actual Python assignment. While in the above example the
65 short form is more convenient, only the most common options have a short form,
66 while any configurable variable in IPython can be set at the command-line by
67 using the long form. This long form is the same syntax used in the
68 configuration files, if you want to set these options permanently.
49 69
50 After the above threading options have been given, regular options can
51 follow in any order. All options can be abbreviated to their shortest
52 non-ambiguous form and are case-sensitive.
53
54 Most options can also be set from your configuration file. See the provided
55 example for more details on what the options do. Options given at the command
56 line override the values set in the configuration file.
57
58 All options with a [no] prepended can be specified in negated form
59 (--no-option instead of --option) to turn the feature off.
60
61 ``-h, --help`` print a help message and exit.
62
63 ``--pylab, pylab=<name>``
64 See :ref:`Matplotlib support <matplotlib_support>`
65 for more details.
66
67 ``--autocall=<val>``
68 Make IPython automatically call any callable object even if you
69 didn't type explicit parentheses. For example, 'str 43' becomes
70 'str(43)' automatically. The value can be '0' to disable the feature,
71 '1' for smart autocall, where it is not applied if there are no more
72 arguments on the line, and '2' for full autocall, where all callable
73 objects are automatically called (even if no arguments are
74 present). The default is '1'.
75
76 ``--[no-]autoindent``
77 Turn automatic indentation on/off.
78
79 ``--[no-]automagic``
80 make magic commands automatic (without needing their first character
81 to be %). Type %magic at the IPython prompt for more information.
82
83 ``--[no-]autoedit_syntax``
84 When a syntax error occurs after editing a file, automatically
85 open the file to the trouble causing line for convenient
86 fixing.
87
88 ``--[no-]banner``
89 Print the initial information banner (default on).
90
91 ``-c <command>``
92 execute the given command string. This is similar to the -c
93 option in the normal Python interpreter.
94
95 ``--cache-size=<n>``
96 size of the output cache (maximum number of entries to hold in
97 memory). The default is 1000, you can change it permanently in your
98 config file. Setting it to 0 completely disables the caching system,
99 and the minimum value accepted is 20 (if you provide a value less than
100 20, it is reset to 0 and a warning is issued) This limit is defined
101 because otherwise you'll spend more time re-flushing a too small cache
102 than working.
103
104 ``--classic``
105 Gives IPython a similar feel to the classic Python
106 prompt.
107
108 ``--colors=<scheme>``
109 Color scheme for prompts and exception reporting. Currently
110 implemented: NoColor, Linux and LightBG.
111
112 ``--[no-]color_info``
113 IPython can display information about objects via a set of functions,
114 and optionally can use colors for this, syntax highlighting source
115 code and various other elements. However, because this information is
116 passed through a pager (like 'less') and many pagers get confused with
117 color codes, this option is off by default. You can test it and turn
118 it on permanently in your configuration file if it works for you. As a
119 reference, the 'less' pager supplied with Mandrake 8.2 works ok, but
120 that in RedHat 7.2 doesn't.
121
122 Test it and turn it on permanently if it works with your
123 system. The magic function %color_info allows you to toggle this
124 interactively for testing.
125
126 ``--[no-]debug``
127 Show information about the loading process. Very useful to pin down
128 problems with your configuration files or to get details about
129 session restores.
130
131 ``--[no-]deep_reload``
132 IPython can use the deep_reload module which reloads changes in
133 modules recursively (it replaces the reload() function, so you don't
134 need to change anything to use it). deep_reload() forces a full
135 reload of modules whose code may have changed, which the default
136 reload() function does not.
137
138 When deep_reload is off, IPython will use the normal reload(),
139 but deep_reload will still be available as dreload(). This
140 feature is off by default [which means that you have both
141 normal reload() and dreload()].
142
143 .. this isn't currently working
144 .. ``--editor=<name>``
145 Which editor to use with the %edit command. By default,
146 IPython will honor your EDITOR environment variable (if not
147 set, vi is the Unix default and notepad the Windows one).
148 Since this editor is invoked on the fly by IPython and is
149 meant for editing small code snippets, you may want to use a
150 small, lightweight editor here (in case your default EDITOR is
151 something like Emacs).
152
153 ``--ipython_dir=<name>``
154 name of your IPython configuration directory IPYTHON_DIR. This
155 can also be specified through the environment variable
156 IPYTHON_DIR.
157
158 ``--logfile=<name>``
159 specify the name of your logfile.
160
161 This implies ``%logstart`` at the beginning of your session
162
163 generate a log file of all input. The file is named
164 ipython_log.py in your current directory (which prevents logs
165 from multiple IPython sessions from trampling each other). You
166 can use this to later restore a session by loading your
167 logfile with ``ipython -i ipython_log.py``
168
169 ``--logplay=<name>``
170
171 NOT AVAILABLE in 0.11
172
173 you can replay a previous log. For restoring a session as close as
174 possible to the state you left it in, use this option (don't just run
175 the logfile). With -logplay, IPython will try to reconstruct the
176 previous working environment in full, not just execute the commands in
177 the logfile.
178
179 When a session is restored, logging is automatically turned on
180 again with the name of the logfile it was invoked with (it is
181 read from the log header). So once you've turned logging on for
182 a session, you can quit IPython and reload it as many times as
183 you want and it will continue to log its history and restore
184 from the beginning every time.
185
186 Caveats: there are limitations in this option. The history
187 variables _i*,_* and _dh don't get restored properly. In the
188 future we will try to implement full session saving by writing
189 and retrieving a 'snapshot' of the memory state of IPython. But
190 our first attempts failed because of inherent limitations of
191 Python's Pickle module, so this may have to wait.
192
193 ``--[no-]messages``
194 Print messages which IPython collects about its startup
195 process (default on).
196
197 ``--[no-]pdb``
198 Automatically call the pdb debugger after every uncaught
199 exception. If you are used to debugging using pdb, this puts
200 you automatically inside of it after any call (either in
201 IPython or in code called by it) which triggers an exception
202 which goes uncaught.
203
204 ``--[no-]pprint``
205 ipython can optionally use the pprint (pretty printer) module
206 for displaying results. pprint tends to give a nicer display
207 of nested data structures. If you like it, you can turn it on
208 permanently in your config file (default off).
209
210 ``--profile=<name>``
211
212 Select the IPython profile by name.
213
214 This is a quick way to keep and load multiple
215 config files for different tasks, especially if you use the
216 include option of config files. You can keep a basic
217 :file:`IPYTHON_DIR/profile_default/ipython_config.py` file
218 and then have other 'profiles' which
219 include this one and load extra things for particular
220 tasks. For example:
221
222 1. $IPYTHON_DIR/profile_default : load basic things you always want.
223 2. $IPYTHON_DIR/profile_math : load (1) and basic math-related modules.
224 3. $IPYTHON_DIR/profile_numeric : load (1) and Numeric and plotting modules.
225
226 Since it is possible to create an endless loop by having
227 circular file inclusions, IPython will stop if it reaches 15
228 recursive inclusions.
229
230 ``PromptManager.in_template=<string>``
231
232 Specify the string used for input prompts. Note that if you are using
233 numbered prompts, the number is represented with a '\#' in the
234 string. Don't forget to quote strings with spaces embedded in
235 them. Default: 'In [\#]:'. The :ref:`prompts section <prompts>`
236 discusses in detail all the available escapes to customize your
237 prompts.
238
239 ``PromptManager.in2_template=<string>``
240 Similar to the previous option, but used for the continuation
241 prompts. The special sequence '\D' is similar to '\#', but
242 with all digits replaced dots (so you can have your
243 continuation prompt aligned with your input prompt). Default:
244 ' .\D.:' (note three spaces at the start for alignment with
245 'In [\#]').
246
247 ``PromptManager.out_template=<string>``
248 String used for output prompts, also uses numbers like
249 in_template. Default: 'Out[\#]:'
250
251 ``--quick``
252 start in bare bones mode (no config file loaded).
253
254 ``config_file=<name>``
255 name of your IPython resource configuration file. Normally
256 IPython loads ipython_config.py (from current directory) or
257 IPYTHON_DIR/profile_default.
258
259 If the loading of your config file fails, IPython starts with
260 a bare bones configuration (no modules loaded at all).
261
262 ``--[no-]readline``
263 use the readline library, which is needed to support name
264 completion and command history, among other things. It is
265 enabled by default, but may cause problems for users of
266 X/Emacs in Python comint or shell buffers.
267
268 Note that X/Emacs 'eterm' buffers (opened with M-x term) support
269 IPython's readline and syntax coloring fine, only 'emacs' (M-x
270 shell and C-c !) buffers do not.
271
272 ``--TerminalInteractiveShell.screen_length=<n>``
273 number of lines of your screen. This is used to control
274 printing of very long strings. Strings longer than this number
275 of lines will be sent through a pager instead of directly
276 printed.
277
278 The default value for this is 0, which means IPython will
279 auto-detect your screen size every time it needs to print certain
280 potentially long strings (this doesn't change the behavior of the
281 'print' keyword, it's only triggered internally). If for some
282 reason this isn't working well (it needs curses support), specify
283 it yourself. Otherwise don't change the default.
284
285 ``--TerminalInteractiveShell.separate_in=<string>``
286
287 separator before input prompts.
288 Default: '\n'
289
290 ``--TerminalInteractiveShell.separate_out=<string>``
291 separator before output prompts.
292 Default: nothing.
293
294 ``--TerminalInteractiveShell.separate_out2=<string>``
295 separator after output prompts.
296 Default: nothing.
297 For these three options, use the value 0 to specify no separator.
298
299 ``--nosep``
300 shorthand for setting the above separators to empty strings.
301
302 Simply removes all input/output separators.
303
304 ``--init``
305 allows you to initialize a profile dir for configuration when you
306 install a new version of IPython or want to use a new profile.
307 Since new versions may include new command line options or example
308 files, this copies updated config files. Note that you should probably
309 use %upgrade instead,it's a safer alternative.
310
311 ``--version`` print version information and exit.
312
313 ``--xmode=<modename>``
314
315 Mode for exception reporting.
316
317 Valid modes: Plain, Context and Verbose.
318
319 * Plain: similar to python's normal traceback printing.
320 * Context: prints 5 lines of context source code around each
321 line in the traceback.
322 * Verbose: similar to Context, but additionally prints the
323 variables currently visible where the exception happened
324 (shortening their strings if too long). This can potentially be
325 very slow, if you happen to have a huge data structure whose
326 string representation is complex to compute. Your computer may
327 appear to freeze for a while with cpu usage at 100%. If this
328 occurs, you can cancel the traceback with Ctrl-C (maybe hitting it
329 more than once).
330 70
331 71 Interactive use
332 72 ===============
333 73
334 74 IPython is meant to work as a drop-in replacement for the standard interactive
335 75 interpreter. As such, any code which is valid python should execute normally
336 76 under IPython (cases where this is not true should be reported as bugs). It
337 77 does, however, offer many features which are not available at a standard python
338 78 prompt. What follows is a list of these.
339 79
340 80
341 81 Caution for Windows users
342 82 -------------------------
343 83
344 84 Windows, unfortunately, uses the '\\' character as a path separator. This is a
345 85 terrible choice, because '\\' also represents the escape character in most
346 86 modern programming languages, including Python. For this reason, using '/'
347 87 character is recommended if you have problems with ``\``. However, in Windows
348 88 commands '/' flags options, so you can not use it for the root directory. This
349 89 means that paths beginning at the root must be typed in a contrived manner
350 90 like: ``%copy \opt/foo/bar.txt \tmp``
351 91
352 92 .. _magic:
353 93
354 94 Magic command system
355 95 --------------------
356 96
357 97 IPython will treat any line whose first character is a % as a special
358 98 call to a 'magic' function. These allow you to control the behavior of
359 99 IPython itself, plus a lot of system-type features. They are all
360 100 prefixed with a % character, but parameters are given without
361 101 parentheses or quotes.
362 102
363 103 Example: typing ``%cd mydir`` changes your working directory to 'mydir', if it
364 104 exists.
365 105
366 106 If you have 'automagic' enabled (as it by default), you don't need
367 107 to type in the % explicitly. IPython will scan its internal list of
368 108 magic functions and call one if it exists. With automagic on you can
369 109 then just type ``cd mydir`` to go to directory 'mydir'. The automagic
370 110 system has the lowest possible precedence in name searches, so defining
371 111 an identifier with the same name as an existing magic function will
372 112 shadow it for automagic use. You can still access the shadowed magic
373 113 function by explicitly using the % character at the beginning of the line.
374 114
375 115 An example (with automagic on) should clarify all this:
376 116
377 117 .. sourcecode:: ipython
378 118
379 119 In [1]: cd ipython # %cd is called by automagic
380 120 /home/fperez/ipython
381 121
382 122 In [2]: cd=1 # now cd is just a variable
383 123
384 124 In [3]: cd .. # and doesn't work as a function anymore
385 125 File "<ipython-input-3-9fedb3aff56c>", line 1
386 126 cd ..
387 127 ^
388 128 SyntaxError: invalid syntax
389 129
390 130
391 131 In [4]: %cd .. # but %cd always works
392 132 /home/fperez
393 133
394 134 In [5]: del cd # if you remove the cd variable, automagic works again
395 135
396 136 In [6]: cd ipython
397 137
398 138 /home/fperez/ipython
399 139
400 140 You can define your own magic functions to extend the system. The
401 141 following example defines a new magic command, %impall:
402 142
403 143 .. sourcecode:: python
404 144
405 145 ip = get_ipython()
406 146
407 147 def doimp(self, arg):
408 148 ip = self.api
409 149 ip.ex("import %s; reload(%s); from %s import *" % (arg,arg,arg) )
410 150
411 151 ip.define_magic('impall', doimp)
412 152
413 153 Type ``%magic`` for more information, including a list of all available magic
414 154 functions at any time and their docstrings. You can also type
415 155 ``%magic_function_name?`` (see :ref:`below <dynamic_object_info>` for information on
416 156 the '?' system) to get information about any particular magic function you are
417 157 interested in.
418 158
419 159 The API documentation for the :mod:`IPython.core.magic` module contains the full
420 160 docstrings of all currently available magic commands.
421 161
422 162
423 163 Access to the standard Python help
424 164 ----------------------------------
425 165
426 166 Simply type ``help()`` to access Python's standard help system. You can
427 167 also type ``help(object)`` for information about a given object, or
428 168 ``help('keyword')`` for information on a keyword. You may need to configure your
429 169 PYTHONDOCS environment variable for this feature to work correctly.
430 170
431 171 .. _dynamic_object_info:
432 172
433 173 Dynamic object information
434 174 --------------------------
435 175
436 176 Typing ``?word`` or ``word?`` prints detailed information about an object. If
437 177 certain strings in the object are too long (e.g. function signatures) they get
438 178 snipped in the center for brevity. This system gives access variable types and
439 179 values, docstrings, function prototypes and other useful information.
440 180
441 181 If the information will not fit in the terminal, it is displayed in a pager
442 182 (``less`` if available, otherwise a basic internal pager).
443 183
444 184 Typing ``??word`` or ``word??`` gives access to the full information, including
445 185 the source code where possible. Long strings are not snipped.
446 186
447 187 The following magic functions are particularly useful for gathering
448 188 information about your working environment. You can get more details by
449 189 typing ``%magic`` or querying them individually (``%function_name?``);
450 190 this is just a summary:
451 191
452 192 * **%pdoc <object>**: Print (or run through a pager if too long) the
453 193 docstring for an object. If the given object is a class, it will
454 194 print both the class and the constructor docstrings.
455 195 * **%pdef <object>**: Print the definition header for any callable
456 196 object. If the object is a class, print the constructor information.
457 197 * **%psource <object>**: Print (or run through a pager if too long)
458 198 the source code for an object.
459 199 * **%pfile <object>**: Show the entire source file where an object was
460 200 defined via a pager, opening it at the line where the object
461 201 definition begins.
462 202 * **%who/%whos**: These functions give information about identifiers
463 203 you have defined interactively (not things you loaded or defined
464 204 in your configuration files). %who just prints a list of
465 205 identifiers and %whos prints a table with some basic details about
466 206 each identifier.
467 207
468 208 Note that the dynamic object information functions (?/??, ``%pdoc``,
469 209 ``%pfile``, ``%pdef``, ``%psource``) work on object attributes, as well as
470 210 directly on variables. For example, after doing ``import os``, you can use
471 211 ``os.path.abspath??``.
472 212
473 213 .. _readline:
474 214
475 215 Readline-based features
476 216 -----------------------
477 217
478 218 These features require the GNU readline library, so they won't work if your
479 219 Python installation lacks readline support. We will first describe the default
480 220 behavior IPython uses, and then how to change it to suit your preferences.
481 221
482 222
483 223 Command line completion
484 224 +++++++++++++++++++++++
485 225
486 226 At any time, hitting TAB will complete any available python commands or
487 227 variable names, and show you a list of the possible completions if
488 228 there's no unambiguous one. It will also complete filenames in the
489 229 current directory if no python names match what you've typed so far.
490 230
491 231
492 232 Search command history
493 233 ++++++++++++++++++++++
494 234
495 235 IPython provides two ways for searching through previous input and thus
496 236 reduce the need for repetitive typing:
497 237
498 238 1. Start typing, and then use Ctrl-p (previous,up) and Ctrl-n
499 239 (next,down) to search through only the history items that match
500 240 what you've typed so far. If you use Ctrl-p/Ctrl-n at a blank
501 241 prompt, they just behave like normal arrow keys.
502 242 2. Hit Ctrl-r: opens a search prompt. Begin typing and the system
503 243 searches your history for lines that contain what you've typed so
504 244 far, completing as much as it can.
505 245
506 246
507 247 Persistent command history across sessions
508 248 ++++++++++++++++++++++++++++++++++++++++++
509 249
510 250 IPython will save your input history when it leaves and reload it next
511 251 time you restart it. By default, the history file is named
512 252 $IPYTHON_DIR/profile_<name>/history.sqlite. This allows you to keep
513 253 separate histories related to various tasks: commands related to
514 254 numerical work will not be clobbered by a system shell history, for
515 255 example.
516 256
517 257
518 258 Autoindent
519 259 ++++++++++
520 260
521 261 IPython can recognize lines ending in ':' and indent the next line,
522 262 while also un-indenting automatically after 'raise' or 'return'.
523 263
524 264 This feature uses the readline library, so it will honor your
525 265 :file:`~/.inputrc` configuration (or whatever file your INPUTRC variable points
526 266 to). Adding the following lines to your :file:`.inputrc` file can make
527 267 indenting/unindenting more convenient (M-i indents, M-u unindents)::
528 268
529 269 $if Python
530 270 "\M-i": " "
531 271 "\M-u": "\d\d\d\d"
532 272 $endif
533 273
534 274 Note that there are 4 spaces between the quote marks after "M-i" above.
535 275
536 276 .. warning::
537 277
538 278 Setting the above indents will cause problems with unicode text entry in
539 279 the terminal.
540 280
541 281 .. warning::
542 282
543 283 Autoindent is ON by default, but it can cause problems with the pasting of
544 284 multi-line indented code (the pasted code gets re-indented on each line). A
545 285 magic function %autoindent allows you to toggle it on/off at runtime. You
546 286 can also disable it permanently on in your :file:`ipython_config.py` file
547 287 (set TerminalInteractiveShell.autoindent=False).
548 288
549 289 If you want to paste multiple lines in the terminal, it is recommended that
550 290 you use ``%paste``.
551 291
552 292
553 293 Customizing readline behavior
554 294 +++++++++++++++++++++++++++++
555 295
556 296 All these features are based on the GNU readline library, which has an
557 297 extremely customizable interface. Normally, readline is configured via a
558 298 file which defines the behavior of the library; the details of the
559 299 syntax for this can be found in the readline documentation available
560 300 with your system or on the Internet. IPython doesn't read this file (if
561 301 it exists) directly, but it does support passing to readline valid
562 302 options via a simple interface. In brief, you can customize readline by
563 303 setting the following options in your configuration file (note
564 304 that these options can not be specified at the command line):
565 305
566 306 * **readline_parse_and_bind**: this holds a list of strings to be executed
567 307 via a readline.parse_and_bind() command. The syntax for valid commands
568 308 of this kind can be found by reading the documentation for the GNU
569 309 readline library, as these commands are of the kind which readline
570 310 accepts in its configuration file.
571 311 * **readline_remove_delims**: a string of characters to be removed
572 312 from the default word-delimiters list used by readline, so that
573 313 completions may be performed on strings which contain them. Do not
574 314 change the default value unless you know what you're doing.
575 315
576 316 You will find the default values in your configuration file.
577 317
578 318
579 319 Session logging and restoring
580 320 -----------------------------
581 321
582 322 You can log all input from a session either by starting IPython with the
583 323 command line switch ``--logfile=foo.py`` (see :ref:`here <command_line_options>`)
584 324 or by activating the logging at any moment with the magic function %logstart.
585 325
586 326 Log files can later be reloaded by running them as scripts and IPython
587 327 will attempt to 'replay' the log by executing all the lines in it, thus
588 328 restoring the state of a previous session. This feature is not quite
589 329 perfect, but can still be useful in many cases.
590 330
591 331 The log files can also be used as a way to have a permanent record of
592 332 any code you wrote while experimenting. Log files are regular text files
593 333 which you can later open in your favorite text editor to extract code or
594 334 to 'clean them up' before using them to replay a session.
595 335
596 336 The `%logstart` function for activating logging in mid-session is used as
597 337 follows::
598 338
599 339 %logstart [log_name [log_mode]]
600 340
601 341 If no name is given, it defaults to a file named 'ipython_log.py' in your
602 342 current working directory, in 'rotate' mode (see below).
603 343
604 344 '%logstart name' saves to file 'name' in 'backup' mode. It saves your
605 345 history up to that point and then continues logging.
606 346
607 347 %logstart takes a second optional parameter: logging mode. This can be
608 348 one of (note that the modes are given unquoted):
609 349
610 350 * [over:] overwrite existing log_name.
611 351 * [backup:] rename (if exists) to log_name~ and start log_name.
612 352 * [append:] well, that says it.
613 353 * [rotate:] create rotating logs log_name.1~, log_name.2~, etc.
614 354
615 355 The %logoff and %logon functions allow you to temporarily stop and
616 356 resume logging to a file which had previously been started with
617 357 %logstart. They will fail (with an explanation) if you try to use them
618 358 before logging has been started.
619 359
620 360 .. _system_shell_access:
621 361
622 362 System shell access
623 363 -------------------
624 364
625 365 Any input line beginning with a ! character is passed verbatim (minus
626 366 the !, of course) to the underlying operating system. For example,
627 367 typing ``!ls`` will run 'ls' in the current directory.
628 368
629 369 Manual capture of command output
630 370 --------------------------------
631 371
632 372 You can assign the result of a system command to a Python variable with the
633 373 syntax ``myfiles = !ls``. This gets machine readable output from stdout
634 374 (e.g. without colours), and splits on newlines. To explicitly get this sort of
635 375 output without assigning to a variable, use two exclamation marks (``!!ls``) or
636 376 the ``%sx`` magic command.
637 377
638 378 The captured list has some convenience features. ``myfiles.n`` or ``myfiles.s``
639 379 returns a string delimited by newlines or spaces, respectively. ``myfiles.p``
640 380 produces `path objects <http://pypi.python.org/pypi/path.py>`_ from the list items.
641 381 See :ref:`string_lists` for details.
642 382
643 383 IPython also allows you to expand the value of python variables when
644 384 making system calls. Wrap variables or expressions in {braces}::
645 385
646 386 In [1]: pyvar = 'Hello world'
647 387 In [2]: !echo "A python variable: {pyvar}"
648 388 A python variable: Hello world
649 389 In [3]: import math
650 390 In [4]: x = 8
651 391 In [5]: !echo {math.factorial(x)}
652 392 40320
653 393
654 394 For simple cases, you can alternatively prepend $ to a variable name::
655 395
656 396 In [6]: !echo $sys.argv
657 397 [/home/fperez/usr/bin/ipython]
658 398 In [7]: !echo "A system variable: $$HOME" # Use $$ for literal $
659 399 A system variable: /home/fperez
660 400
661 401 System command aliases
662 402 ----------------------
663 403
664 404 The %alias magic function allows you to define magic functions which are in fact
665 405 system shell commands. These aliases can have parameters.
666 406
667 407 ``%alias alias_name cmd`` defines 'alias_name' as an alias for 'cmd'
668 408
669 409 Then, typing ``alias_name params`` will execute the system command 'cmd
670 410 params' (from your underlying operating system).
671 411
672 412 You can also define aliases with parameters using %s specifiers (one per
673 413 parameter). The following example defines the parts function as an
674 414 alias to the command 'echo first %s second %s' where each %s will be
675 415 replaced by a positional parameter to the call to %parts::
676 416
677 417 In [1]: %alias parts echo first %s second %s
678 418 In [2]: parts A B
679 419 first A second B
680 420 In [3]: parts A
681 421 ERROR: Alias <parts> requires 2 arguments, 1 given.
682 422
683 423 If called with no parameters, %alias prints the table of currently
684 424 defined aliases.
685 425
686 426 The %rehashx magic allows you to load your entire $PATH as
687 427 ipython aliases. See its docstring for further details.
688 428
689 429
690 430 .. _dreload:
691 431
692 432 Recursive reload
693 433 ----------------
694 434
695 435 The :mod:`IPython.lib.deepreload` module allows you to recursively reload a
696 436 module: changes made to any of its dependencies will be reloaded without
697 437 having to exit. To start using it, do::
698 438
699 439 from IPython.lib.deepreload import reload as dreload
700 440
701 441
702 442 Verbose and colored exception traceback printouts
703 443 -------------------------------------------------
704 444
705 445 IPython provides the option to see very detailed exception tracebacks,
706 446 which can be especially useful when debugging large programs. You can
707 447 run any Python file with the %run function to benefit from these
708 448 detailed tracebacks. Furthermore, both normal and verbose tracebacks can
709 449 be colored (if your terminal supports it) which makes them much easier
710 450 to parse visually.
711 451
712 452 See the magic xmode and colors functions for details (just type %magic).
713 453
714 454 These features are basically a terminal version of Ka-Ping Yee's cgitb
715 455 module, now part of the standard Python library.
716 456
717 457
718 458 .. _input_caching:
719 459
720 460 Input caching system
721 461 --------------------
722 462
723 463 IPython offers numbered prompts (In/Out) with input and output caching
724 464 (also referred to as 'input history'). All input is saved and can be
725 465 retrieved as variables (besides the usual arrow key recall), in
726 466 addition to the %rep magic command that brings a history entry
727 467 up for editing on the next command line.
728 468
729 469 The following GLOBAL variables always exist (so don't overwrite them!):
730 470
731 471 * _i, _ii, _iii: store previous, next previous and next-next previous inputs.
732 472 * In, _ih : a list of all inputs; _ih[n] is the input from line n. If you
733 473 overwrite In with a variable of your own, you can remake the assignment to the
734 474 internal list with a simple ``In=_ih``.
735 475
736 476 Additionally, global variables named _i<n> are dynamically created (<n>
737 477 being the prompt counter), so ``_i<n> == _ih[<n>] == In[<n>]``.
738 478
739 479 For example, what you typed at prompt 14 is available as _i14, _ih[14]
740 480 and In[14].
741 481
742 482 This allows you to easily cut and paste multi line interactive prompts
743 483 by printing them out: they print like a clean string, without prompt
744 484 characters. You can also manipulate them like regular variables (they
745 485 are strings), modify or exec them (typing ``exec _i9`` will re-execute the
746 486 contents of input prompt 9.
747 487
748 488 You can also re-execute multiple lines of input easily by using the
749 489 magic %rerun or %macro functions. The macro system also allows you to re-execute
750 490 previous lines which include magic function calls (which require special
751 491 processing). Type %macro? for more details on the macro system.
752 492
753 493 A history function %hist allows you to see any part of your input
754 494 history by printing a range of the _i variables.
755 495
756 496 You can also search ('grep') through your history by typing
757 497 ``%hist -g somestring``. This is handy for searching for URLs, IP addresses,
758 498 etc. You can bring history entries listed by '%hist -g' up for editing
759 499 with the %recall command, or run them immediately with %rerun.
760 500
761 501 .. _output_caching:
762 502
763 503 Output caching system
764 504 ---------------------
765 505
766 506 For output that is returned from actions, a system similar to the input
767 507 cache exists but using _ instead of _i. Only actions that produce a
768 508 result (NOT assignments, for example) are cached. If you are familiar
769 509 with Mathematica, IPython's _ variables behave exactly like
770 510 Mathematica's % variables.
771 511
772 512 The following GLOBAL variables always exist (so don't overwrite them!):
773 513
774 514 * [_] (a single underscore) : stores previous output, like Python's
775 515 default interpreter.
776 516 * [__] (two underscores): next previous.
777 517 * [___] (three underscores): next-next previous.
778 518
779 519 Additionally, global variables named _<n> are dynamically created (<n>
780 520 being the prompt counter), such that the result of output <n> is always
781 521 available as _<n> (don't use the angle brackets, just the number, e.g.
782 522 _21).
783 523
784 524 These variables are also stored in a global dictionary (not a
785 525 list, since it only has entries for lines which returned a result)
786 526 available under the names _oh and Out (similar to _ih and In). So the
787 527 output from line 12 can be obtained as _12, Out[12] or _oh[12]. If you
788 528 accidentally overwrite the Out variable you can recover it by typing
789 529 'Out=_oh' at the prompt.
790 530
791 531 This system obviously can potentially put heavy memory demands on your
792 532 system, since it prevents Python's garbage collector from removing any
793 533 previously computed results. You can control how many results are kept
794 534 in memory with the option (at the command line or in your configuration
795 535 file) cache_size. If you set it to 0, the whole system is completely
796 536 disabled and the prompts revert to the classic '>>>' of normal Python.
797 537
798 538
799 539 Directory history
800 540 -----------------
801 541
802 542 Your history of visited directories is kept in the global list _dh, and
803 543 the magic %cd command can be used to go to any entry in that list. The
804 544 %dhist command allows you to view this history. Do ``cd -<TAB>`` to
805 545 conveniently view the directory history.
806 546
807 547
808 548 Automatic parentheses and quotes
809 549 --------------------------------
810 550
811 551 These features were adapted from Nathan Gray's LazyPython. They are
812 552 meant to allow less typing for common situations.
813 553
814 554
815 555 Automatic parentheses
816 556 +++++++++++++++++++++
817 557
818 558 Callable objects (i.e. functions, methods, etc) can be invoked like this
819 559 (notice the commas between the arguments)::
820 560
821 561 In [1]: callable_ob arg1, arg2, arg3
822 562 ------> callable_ob(arg1, arg2, arg3)
823 563
824 564 You can force automatic parentheses by using '/' as the first character
825 565 of a line. For example::
826 566
827 567 In [2]: /globals # becomes 'globals()'
828 568
829 569 Note that the '/' MUST be the first character on the line! This won't work::
830 570
831 571 In [3]: print /globals # syntax error
832 572
833 573 In most cases the automatic algorithm should work, so you should rarely
834 574 need to explicitly invoke /. One notable exception is if you are trying
835 575 to call a function with a list of tuples as arguments (the parenthesis
836 576 will confuse IPython)::
837 577
838 578 In [4]: zip (1,2,3),(4,5,6) # won't work
839 579
840 580 but this will work::
841 581
842 582 In [5]: /zip (1,2,3),(4,5,6)
843 583 ------> zip ((1,2,3),(4,5,6))
844 584 Out[5]: [(1, 4), (2, 5), (3, 6)]
845 585
846 586 IPython tells you that it has altered your command line by displaying
847 587 the new command line preceded by ->. e.g.::
848 588
849 589 In [6]: callable list
850 590 ------> callable(list)
851 591
852 592
853 593 Automatic quoting
854 594 +++++++++++++++++
855 595
856 596 You can force automatic quoting of a function's arguments by using ','
857 597 or ';' as the first character of a line. For example::
858 598
859 599 In [1]: ,my_function /home/me # becomes my_function("/home/me")
860 600
861 601 If you use ';' the whole argument is quoted as a single string, while ',' splits
862 602 on whitespace::
863 603
864 604 In [2]: ,my_function a b c # becomes my_function("a","b","c")
865 605
866 606 In [3]: ;my_function a b c # becomes my_function("a b c")
867 607
868 608 Note that the ',' or ';' MUST be the first character on the line! This
869 609 won't work::
870 610
871 611 In [4]: x = ,my_function /home/me # syntax error
872 612
873 613 IPython as your default Python environment
874 614 ==========================================
875 615
876 616 Python honors the environment variable PYTHONSTARTUP and will execute at
877 617 startup the file referenced by this variable. If you put the following code at
878 618 the end of that file, then IPython will be your working environment anytime you
879 619 start Python::
880 620
881 621 from IPython.frontend.terminal.ipapp import launch_new_instance
882 622 launch_new_instance()
883 623 raise SystemExit
884 624
885 625 The ``raise SystemExit`` is needed to exit Python when
886 626 it finishes, otherwise you'll be back at the normal Python '>>>'
887 627 prompt.
888 628
889 629 This is probably useful to developers who manage multiple Python
890 630 versions and don't want to have correspondingly multiple IPython
891 631 versions. Note that in this mode, there is no way to pass IPython any
892 632 command-line options, as those are trapped first by Python itself.
893 633
894 634 .. _Embedding:
895 635
896 636 Embedding IPython
897 637 =================
898 638
899 639 It is possible to start an IPython instance inside your own Python
900 640 programs. This allows you to evaluate dynamically the state of your
901 641 code, operate with your variables, analyze them, etc. Note however that
902 642 any changes you make to values while in the shell do not propagate back
903 643 to the running code, so it is safe to modify your values because you
904 644 won't break your code in bizarre ways by doing so.
905 645
906 646 .. note::
907 647
908 648 At present, trying to embed IPython from inside IPython causes problems. Run
909 649 the code samples below outside IPython.
910 650
911 651 This feature allows you to easily have a fully functional python
912 652 environment for doing object introspection anywhere in your code with a
913 653 simple function call. In some cases a simple print statement is enough,
914 654 but if you need to do more detailed analysis of a code fragment this
915 655 feature can be very valuable.
916 656
917 657 It can also be useful in scientific computing situations where it is
918 658 common to need to do some automatic, computationally intensive part and
919 659 then stop to look at data, plots, etc.
920 660 Opening an IPython instance will give you full access to your data and
921 661 functions, and you can resume program execution once you are done with
922 662 the interactive part (perhaps to stop again later, as many times as
923 663 needed).
924 664
925 665 The following code snippet is the bare minimum you need to include in
926 666 your Python programs for this to work (detailed examples follow later)::
927 667
928 668 from IPython import embed
929 669
930 670 embed() # this call anywhere in your program will start IPython
931 671
932 672 You can run embedded instances even in code which is itself being run at
933 673 the IPython interactive prompt with '%run <filename>'. Since it's easy
934 674 to get lost as to where you are (in your top-level IPython or in your
935 675 embedded one), it's a good idea in such cases to set the in/out prompts
936 676 to something different for the embedded instances. The code examples
937 677 below illustrate this.
938 678
939 679 You can also have multiple IPython instances in your program and open
940 680 them separately, for example with different options for data
941 681 presentation. If you close and open the same instance multiple times,
942 682 its prompt counters simply continue from each execution to the next.
943 683
944 684 Please look at the docstrings in the :mod:`~IPython.frontend.terminal.embed`
945 685 module for more details on the use of this system.
946 686
947 687 The following sample file illustrating how to use the embedding
948 688 functionality is provided in the examples directory as example-embed.py.
949 689 It should be fairly self-explanatory:
950 690
951 691 .. literalinclude:: ../../examples/core/example-embed.py
952 692 :language: python
953 693
954 694 Once you understand how the system functions, you can use the following
955 695 code fragments in your programs which are ready for cut and paste:
956 696
957 697 .. literalinclude:: ../../examples/core/example-embed-short.py
958 698 :language: python
959 699
960 700 Using the Python debugger (pdb)
961 701 ===============================
962 702
963 703 Running entire programs via pdb
964 704 -------------------------------
965 705
966 706 pdb, the Python debugger, is a powerful interactive debugger which
967 707 allows you to step through code, set breakpoints, watch variables,
968 708 etc. IPython makes it very easy to start any script under the control
969 709 of pdb, regardless of whether you have wrapped it into a 'main()'
970 710 function or not. For this, simply type '%run -d myscript' at an
971 711 IPython prompt. See the %run command's documentation (via '%run?' or
972 712 in Sec. magic_ for more details, including how to control where pdb
973 713 will stop execution first.
974 714
975 715 For more information on the use of the pdb debugger, read the included
976 716 pdb.doc file (part of the standard Python distribution). On a stock
977 717 Linux system it is located at /usr/lib/python2.3/pdb.doc, but the
978 718 easiest way to read it is by using the help() function of the pdb module
979 719 as follows (in an IPython prompt)::
980 720
981 721 In [1]: import pdb
982 722 In [2]: pdb.help()
983 723
984 724 This will load the pdb.doc document in a file viewer for you automatically.
985 725
986 726
987 727 Automatic invocation of pdb on exceptions
988 728 -----------------------------------------
989 729
990 730 IPython, if started with the ``--pdb`` option (or if the option is set in
991 731 your config file) can call the Python pdb debugger every time your code
992 732 triggers an uncaught exception. This feature
993 733 can also be toggled at any time with the %pdb magic command. This can be
994 734 extremely useful in order to find the origin of subtle bugs, because pdb
995 735 opens up at the point in your code which triggered the exception, and
996 736 while your program is at this point 'dead', all the data is still
997 737 available and you can walk up and down the stack frame and understand
998 738 the origin of the problem.
999 739
1000 740 Furthermore, you can use these debugging facilities both with the
1001 741 embedded IPython mode and without IPython at all. For an embedded shell
1002 742 (see sec. Embedding_), simply call the constructor with
1003 743 ``--pdb`` in the argument string and pdb will automatically be called if an
1004 744 uncaught exception is triggered by your code.
1005 745
1006 746 For stand-alone use of the feature in your programs which do not use
1007 747 IPython at all, put the following lines toward the top of your 'main'
1008 748 routine::
1009 749
1010 750 import sys
1011 751 from IPython.core import ultratb
1012 752 sys.excepthook = ultratb.FormattedTB(mode='Verbose',
1013 753 color_scheme='Linux', call_pdb=1)
1014 754
1015 755 The mode keyword can be either 'Verbose' or 'Plain', giving either very
1016 756 detailed or normal tracebacks respectively. The color_scheme keyword can
1017 757 be one of 'NoColor', 'Linux' (default) or 'LightBG'. These are the same
1018 758 options which can be set in IPython with ``--colors`` and ``--xmode``.
1019 759
1020 760 This will give any of your programs detailed, colored tracebacks with
1021 761 automatic invocation of pdb.
1022 762
1023 763
1024 764 Extensions for syntax processing
1025 765 ================================
1026 766
1027 767 This isn't for the faint of heart, because the potential for breaking
1028 768 things is quite high. But it can be a very powerful and useful feature.
1029 769 In a nutshell, you can redefine the way IPython processes the user input
1030 770 line to accept new, special extensions to the syntax without needing to
1031 771 change any of IPython's own code.
1032 772
1033 773 In the IPython/extensions directory you will find some examples
1034 774 supplied, which we will briefly describe now. These can be used 'as is'
1035 775 (and both provide very useful functionality), or you can use them as a
1036 776 starting point for writing your own extensions.
1037 777
1038 778 .. _pasting_with_prompts:
1039 779
1040 780 Pasting of code starting with Python or IPython prompts
1041 781 -------------------------------------------------------
1042 782
1043 783 IPython is smart enough to filter out input prompts, be they plain Python ones
1044 784 (``>>>`` and ``...``) or IPython ones (``In [N]:`` and `` ...:``). You can
1045 785 therefore copy and paste from existing interactive sessions without worry.
1046 786
1047 787 The following is a 'screenshot' of how things work, copying an example from the
1048 788 standard Python tutorial::
1049 789
1050 790 In [1]: >>> # Fibonacci series:
1051 791
1052 792 In [2]: ... # the sum of two elements defines the next
1053 793
1054 794 In [3]: ... a, b = 0, 1
1055 795
1056 796 In [4]: >>> while b < 10:
1057 797 ...: ... print b
1058 798 ...: ... a, b = b, a+b
1059 799 ...:
1060 800 1
1061 801 1
1062 802 2
1063 803 3
1064 804 5
1065 805 8
1066 806
1067 807 And pasting from IPython sessions works equally well::
1068 808
1069 809 In [1]: In [5]: def f(x):
1070 810 ...: ...: "A simple function"
1071 811 ...: ...: return x**2
1072 812 ...: ...:
1073 813
1074 814 In [2]: f(3)
1075 815 Out[2]: 9
1076 816
1077 817 .. _gui_support:
1078 818
1079 819 GUI event loop support
1080 820 ======================
1081 821
1082 822 .. versionadded:: 0.11
1083 823 The ``%gui`` magic and :mod:`IPython.lib.inputhook`.
1084 824
1085 825 IPython has excellent support for working interactively with Graphical User
1086 826 Interface (GUI) toolkits, such as wxPython, PyQt4/PySide, PyGTK and Tk. This is
1087 827 implemented using Python's builtin ``PyOSInputHook`` hook. This implementation
1088 828 is extremely robust compared to our previous thread-based version. The
1089 829 advantages of this are:
1090 830
1091 831 * GUIs can be enabled and disabled dynamically at runtime.
1092 832 * The active GUI can be switched dynamically at runtime.
1093 833 * In some cases, multiple GUIs can run simultaneously with no problems.
1094 834 * There is a developer API in :mod:`IPython.lib.inputhook` for customizing
1095 835 all of these things.
1096 836
1097 837 For users, enabling GUI event loop integration is simple. You simple use the
1098 838 ``%gui`` magic as follows::
1099 839
1100 840 %gui [GUINAME]
1101 841
1102 842 With no arguments, ``%gui`` removes all GUI support. Valid ``GUINAME``
1103 843 arguments are ``wx``, ``qt``, ``gtk`` and ``tk``.
1104 844
1105 845 Thus, to use wxPython interactively and create a running :class:`wx.App`
1106 846 object, do::
1107 847
1108 848 %gui wx
1109 849
1110 850 For information on IPython's Matplotlib integration (and the ``pylab`` mode)
1111 851 see :ref:`this section <matplotlib_support>`.
1112 852
1113 853 For developers that want to use IPython's GUI event loop integration in the
1114 854 form of a library, these capabilities are exposed in library form in the
1115 855 :mod:`IPython.lib.inputhook` and :mod:`IPython.lib.guisupport` modules.
1116 856 Interested developers should see the module docstrings for more information,
1117 857 but there are a few points that should be mentioned here.
1118 858
1119 859 First, the ``PyOSInputHook`` approach only works in command line settings
1120 860 where readline is activated. The integration with various eventloops
1121 861 is handled somewhat differently (and more simply) when using the standalone
1122 862 kernel, as in the qtconsole and notebook.
1123 863
1124 864 Second, when using the ``PyOSInputHook`` approach, a GUI application should
1125 865 *not* start its event loop. Instead all of this is handled by the
1126 866 ``PyOSInputHook``. This means that applications that are meant to be used both
1127 867 in IPython and as standalone apps need to have special code to detects how the
1128 868 application is being run. We highly recommend using IPython's support for this.
1129 869 Since the details vary slightly between toolkits, we point you to the various
1130 870 examples in our source directory :file:`docs/examples/lib` that demonstrate
1131 871 these capabilities.
1132 872
1133 873 .. warning::
1134 874
1135 875 The WX version of this is currently broken. While ``--pylab=wx`` works
1136 876 fine, standalone WX apps do not. See
1137 877 https://github.com/ipython/ipython/issues/645 for details of our progress on
1138 878 this issue.
1139 879
1140 880
1141 881 Third, unlike previous versions of IPython, we no longer "hijack" (replace
1142 882 them with no-ops) the event loops. This is done to allow applications that
1143 883 actually need to run the real event loops to do so. This is often needed to
1144 884 process pending events at critical points.
1145 885
1146 886 Finally, we also have a number of examples in our source directory
1147 887 :file:`docs/examples/lib` that demonstrate these capabilities.
1148 888
1149 889 PyQt and PySide
1150 890 ---------------
1151 891
1152 892 .. attempt at explanation of the complete mess that is Qt support
1153 893
1154 894 When you use ``--gui=qt`` or ``--pylab=qt``, IPython can work with either
1155 895 PyQt4 or PySide. There are three options for configuration here, because
1156 896 PyQt4 has two APIs for QString and QVariant - v1, which is the default on
1157 897 Python 2, and the more natural v2, which is the only API supported by PySide.
1158 898 v2 is also the default for PyQt4 on Python 3. IPython's code for the QtConsole
1159 899 uses v2, but you can still use any interface in your code, since the
1160 900 Qt frontend is in a different process.
1161 901
1162 902 The default will be to import PyQt4 without configuration of the APIs, thus
1163 903 matching what most applications would expect. It will fall back of PySide if
1164 904 PyQt4 is unavailable.
1165 905
1166 906 If specified, IPython will respect the environment variable ``QT_API`` used
1167 907 by ETS. ETS 4.0 also works with both PyQt4 and PySide, but it requires
1168 908 PyQt4 to use its v2 API. So if ``QT_API=pyside`` PySide will be used,
1169 909 and if ``QT_API=pyqt`` then PyQt4 will be used *with the v2 API* for
1170 910 QString and QVariant, so ETS codes like MayaVi will also work with IPython.
1171 911
1172 912 If you launch IPython in pylab mode with ``ipython --pylab=qt``, then IPython
1173 913 will ask matplotlib which Qt library to use (only if QT_API is *not set*), via
1174 914 the 'backend.qt4' rcParam. If matplotlib is version 1.0.1 or older, then
1175 915 IPython will always use PyQt4 without setting the v2 APIs, since neither v2
1176 916 PyQt nor PySide work.
1177 917
1178 918 .. warning::
1179 919
1180 920 Note that this means for ETS 4 to work with PyQt4, ``QT_API`` *must* be set
1181 921 to work with IPython's qt integration, because otherwise PyQt4 will be
1182 922 loaded in an incompatible mode.
1183 923
1184 924 It also means that you must *not* have ``QT_API`` set if you want to
1185 925 use ``--gui=qt`` with code that requires PyQt4 API v1.
1186 926
1187 927
1188 928 .. _matplotlib_support:
1189 929
1190 930 Plotting with matplotlib
1191 931 ========================
1192 932
1193 933 `Matplotlib`_ provides high quality 2D and 3D plotting for Python. Matplotlib
1194 934 can produce plots on screen using a variety of GUI toolkits, including Tk,
1195 935 PyGTK, PyQt4 and wxPython. It also provides a number of commands useful for
1196 936 scientific computing, all with a syntax compatible with that of the popular
1197 937 Matlab program.
1198 938
1199 939 To start IPython with matplotlib support, use the ``--pylab`` switch. If no
1200 940 arguments are given, IPython will automatically detect your choice of
1201 941 matplotlib backend. You can also request a specific backend with
1202 942 ``--pylab=backend``, where ``backend`` must be one of: 'tk', 'qt', 'wx', 'gtk',
1203 943 'osx'.
1204 944
1205 945 .. _Matplotlib: http://matplotlib.sourceforge.net
1206 946
1207 947 .. _interactive_demos:
1208 948
1209 949 Interactive demos with IPython
1210 950 ==============================
1211 951
1212 952 IPython ships with a basic system for running scripts interactively in
1213 953 sections, useful when presenting code to audiences. A few tags embedded
1214 954 in comments (so that the script remains valid Python code) divide a file
1215 955 into separate blocks, and the demo can be run one block at a time, with
1216 956 IPython printing (with syntax highlighting) the block before executing
1217 957 it, and returning to the interactive prompt after each block. The
1218 958 interactive namespace is updated after each block is run with the
1219 959 contents of the demo's namespace.
1220 960
1221 961 This allows you to show a piece of code, run it and then execute
1222 962 interactively commands based on the variables just created. Once you
1223 963 want to continue, you simply execute the next block of the demo. The
1224 964 following listing shows the markup necessary for dividing a script into
1225 965 sections for execution as a demo:
1226 966
1227 967 .. literalinclude:: ../../examples/lib/example-demo.py
1228 968 :language: python
1229 969
1230 970 In order to run a file as a demo, you must first make a Demo object out
1231 971 of it. If the file is named myscript.py, the following code will make a
1232 972 demo::
1233 973
1234 974 from IPython.lib.demo import Demo
1235 975
1236 976 mydemo = Demo('myscript.py')
1237 977
1238 978 This creates the mydemo object, whose blocks you run one at a time by
1239 979 simply calling the object with no arguments. If you have autocall active
1240 980 in IPython (the default), all you need to do is type::
1241 981
1242 982 mydemo
1243 983
1244 984 and IPython will call it, executing each block. Demo objects can be
1245 985 restarted, you can move forward or back skipping blocks, re-execute the
1246 986 last block, etc. Simply use the Tab key on a demo object to see its
1247 987 methods, and call '?' on them to see their docstrings for more usage
1248 988 details. In addition, the demo module itself contains a comprehensive
1249 989 docstring, which you can access via::
1250 990
1251 991 from IPython.lib import demo
1252 992
1253 993 demo?
1254 994
1255 995 Limitations: It is important to note that these demos are limited to
1256 996 fairly simple uses. In particular, you cannot break up sections within
1257 997 indented code (loops, if statements, function definitions, etc.)
1258 998 Supporting something like this would basically require tracking the
1259 999 internal execution state of the Python interpreter, so only top-level
1260 1000 divisions are allowed. If you want to be able to open an IPython
1261 1001 instance at an arbitrary point in a program, you can use IPython's
1262 1002 embedding facilities, see :func:`IPython.embed` for details.
1263 1003
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