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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 .. note::
15
16 For IPython on Python 3, use ``ipython3`` in place of ``ipython``.
17
14 18 If invoked with no options, it executes all the files listed in sequence
15 19 and drops you into the interpreter while still acknowledging any options
16 20 you may have set in your ipython_config.py. This behavior is different from
17 21 standard Python, which when called as python -i will only execute one
18 22 file and ignore your configuration setup.
19 23
20 24 Please note that some of the configuration options are not available at
21 25 the command line, simply because they are not practical here. Look into
22 26 your configuration files for details on those. There are separate configuration
23 27 files for each profile, and the files look like "ipython_config.py" or
24 28 "ipython_config_<frontendname>.py". Profile directories look like
25 29 "profile_profilename" and are typically installed in the IPYTHON_DIR directory.
26 30 For Linux users, this will be $HOME/.config/ipython, and for other users it
27 31 will be $HOME/.ipython. For Windows users, $HOME resolves to C:\\Documents and
28 32 Settings\\YourUserName in most instances.
29 33
30 34
31 35 Eventloop integration
32 36 ---------------------
33 37
34 38 Previously IPython had command line options for controlling GUI event loop
35 39 integration (-gthread, -qthread, -q4thread, -wthread, -pylab). As of IPython
36 40 version 0.11, these have been removed. Please see the new ``%gui``
37 41 magic command or :ref:`this section <gui_support>` for details on the new
38 42 interface, or specify the gui at the commandline::
39 43
40 44 $ ipython --gui=qt
41 45
42 46
43 47 Regular Options
44 48 ---------------
45 49
46 50 After the above threading options have been given, regular options can
47 51 follow in any order. All options can be abbreviated to their shortest
48 non-ambiguous form and are case-sensitive. One or two dashes can be
49 used. Some options have an alternate short form, indicated after a ``|``.
52 non-ambiguous form and are case-sensitive.
50 53
51 54 Most options can also be set from your configuration file. See the provided
52 55 example for more details on what the options do. Options given at the command
53 56 line override the values set in the configuration file.
54 57
55 58 All options with a [no] prepended can be specified in negated form
56 59 (--no-option instead of --option) to turn the feature off.
57 60
58 61 ``-h, --help`` print a help message and exit.
59 62
60 63 ``--pylab, pylab=<name>``
61 64 See :ref:`Matplotlib support <matplotlib_support>`
62 65 for more details.
63 66
64 67 ``--autocall=<val>``
65 68 Make IPython automatically call any callable object even if you
66 69 didn't type explicit parentheses. For example, 'str 43' becomes
67 70 'str(43)' automatically. The value can be '0' to disable the feature,
68 71 '1' for smart autocall, where it is not applied if there are no more
69 72 arguments on the line, and '2' for full autocall, where all callable
70 73 objects are automatically called (even if no arguments are
71 74 present). The default is '1'.
72 75
73 76 ``--[no-]autoindent``
74 77 Turn automatic indentation on/off.
75 78
76 79 ``--[no-]automagic``
77 80 make magic commands automatic (without needing their first character
78 81 to be %). Type %magic at the IPython prompt for more information.
79 82
80 83 ``--[no-]autoedit_syntax``
81 84 When a syntax error occurs after editing a file, automatically
82 85 open the file to the trouble causing line for convenient
83 86 fixing.
84 87
85 88 ``--[no-]banner``
86 89 Print the initial information banner (default on).
87 90
88 91 ``-c <command>``
89 92 execute the given command string. This is similar to the -c
90 93 option in the normal Python interpreter.
91 94
92 95 ``--cache-size=<n>``
93 96 size of the output cache (maximum number of entries to hold in
94 97 memory). The default is 1000, you can change it permanently in your
95 98 config file. Setting it to 0 completely disables the caching system,
96 99 and the minimum value accepted is 20 (if you provide a value less than
97 100 20, it is reset to 0 and a warning is issued) This limit is defined
98 101 because otherwise you'll spend more time re-flushing a too small cache
99 102 than working.
100 103
101 104 ``--classic``
102 105 Gives IPython a similar feel to the classic Python
103 106 prompt.
104 107
105 108 ``--colors=<scheme>``
106 109 Color scheme for prompts and exception reporting. Currently
107 110 implemented: NoColor, Linux and LightBG.
108 111
109 112 ``--[no-]color_info``
110 113 IPython can display information about objects via a set of functions,
111 114 and optionally can use colors for this, syntax highlighting source
112 115 code and various other elements. However, because this information is
113 116 passed through a pager (like 'less') and many pagers get confused with
114 117 color codes, this option is off by default. You can test it and turn
115 118 it on permanently in your configuration file if it works for you. As a
116 119 reference, the 'less' pager supplied with Mandrake 8.2 works ok, but
117 120 that in RedHat 7.2 doesn't.
118 121
119 122 Test it and turn it on permanently if it works with your
120 123 system. The magic function %color_info allows you to toggle this
121 124 interactively for testing.
122 125
123 126 ``--[no-]debug``
124 127 Show information about the loading process. Very useful to pin down
125 128 problems with your configuration files or to get details about
126 129 session restores.
127 130
128 131 ``--[no-]deep_reload``
129 132 IPython can use the deep_reload module which reloads changes in
130 133 modules recursively (it replaces the reload() function, so you don't
131 134 need to change anything to use it). deep_reload() forces a full
132 135 reload of modules whose code may have changed, which the default
133 136 reload() function does not.
134 137
135 138 When deep_reload is off, IPython will use the normal reload(),
136 139 but deep_reload will still be available as dreload(). This
137 140 feature is off by default [which means that you have both
138 141 normal reload() and dreload()].
139 142
140 143 ``--editor=<name>``
141 144 Which editor to use with the %edit command. By default,
142 145 IPython will honor your EDITOR environment variable (if not
143 146 set, vi is the Unix default and notepad the Windows one).
144 147 Since this editor is invoked on the fly by IPython and is
145 148 meant for editing small code snippets, you may want to use a
146 149 small, lightweight editor here (in case your default EDITOR is
147 150 something like Emacs).
148 151
149 152 ``--ipython_dir=<name>``
150 153 name of your IPython configuration directory IPYTHON_DIR. This
151 154 can also be specified through the environment variable
152 155 IPYTHON_DIR.
153 156
154 157 ``--logfile=<name>``
155 158 specify the name of your logfile.
156 159
157 160 This implies ``%logstart`` at the beginning of your session
158 161
159 162 generate a log file of all input. The file is named
160 163 ipython_log.py in your current directory (which prevents logs
161 164 from multiple IPython sessions from trampling each other). You
162 165 can use this to later restore a session by loading your
163 166 logfile with ``ipython -i ipython_log.py``
164 167
165 168 ``--logplay=<name>``
166 169
167 170 NOT AVAILABLE in 0.11
168 171
169 172 you can replay a previous log. For restoring a session as close as
170 173 possible to the state you left it in, use this option (don't just run
171 174 the logfile). With -logplay, IPython will try to reconstruct the
172 175 previous working environment in full, not just execute the commands in
173 176 the logfile.
174 177
175 178 When a session is restored, logging is automatically turned on
176 179 again with the name of the logfile it was invoked with (it is
177 180 read from the log header). So once you've turned logging on for
178 181 a session, you can quit IPython and reload it as many times as
179 182 you want and it will continue to log its history and restore
180 183 from the beginning every time.
181 184
182 185 Caveats: there are limitations in this option. The history
183 186 variables _i*,_* and _dh don't get restored properly. In the
184 187 future we will try to implement full session saving by writing
185 188 and retrieving a 'snapshot' of the memory state of IPython. But
186 189 our first attempts failed because of inherent limitations of
187 190 Python's Pickle module, so this may have to wait.
188 191
189 192 ``--[no-]messages``
190 193 Print messages which IPython collects about its startup
191 194 process (default on).
192 195
193 196 ``--[no-]pdb``
194 197 Automatically call the pdb debugger after every uncaught
195 198 exception. If you are used to debugging using pdb, this puts
196 199 you automatically inside of it after any call (either in
197 200 IPython or in code called by it) which triggers an exception
198 201 which goes uncaught.
199 202
200 203 ``--[no-]pprint``
201 204 ipython can optionally use the pprint (pretty printer) module
202 205 for displaying results. pprint tends to give a nicer display
203 206 of nested data structures. If you like it, you can turn it on
204 207 permanently in your config file (default off).
205 208
206 209 ``--profile=<name>``
207 210
208 211 Select the IPython profile by name.
209 212
210 213 This is a quick way to keep and load multiple
211 214 config files for different tasks, especially if you use the
212 215 include option of config files. You can keep a basic
213 216 :file:`IPYTHON_DIR/profile_default/ipython_config.py` file
214 217 and then have other 'profiles' which
215 218 include this one and load extra things for particular
216 219 tasks. For example:
217 220
218 221 1. $IPYTHON_DIR/profile_default : load basic things you always want.
219 222 2. $IPYTHON_DIR/profile_math : load (1) and basic math-related modules.
220 223 3. $IPYTHON_DIR/profile_numeric : load (1) and Numeric and plotting modules.
221 224
222 225 Since it is possible to create an endless loop by having
223 226 circular file inclusions, IPython will stop if it reaches 15
224 227 recursive inclusions.
225 228
226 229 ``InteractiveShell.prompt_in1=<string>``
227 230
228 231 Specify the string used for input prompts. Note that if you are using
229 232 numbered prompts, the number is represented with a '\#' in the
230 233 string. Don't forget to quote strings with spaces embedded in
231 234 them. Default: 'In [\#]:'. The :ref:`prompts section <prompts>`
232 235 discusses in detail all the available escapes to customize your
233 236 prompts.
234 237
235 238 ``InteractiveShell.prompt_in2=<string>``
236 239 Similar to the previous option, but used for the continuation
237 240 prompts. The special sequence '\D' is similar to '\#', but
238 241 with all digits replaced dots (so you can have your
239 242 continuation prompt aligned with your input prompt). Default:
240 243 ' .\D.:' (note three spaces at the start for alignment with
241 244 'In [\#]').
242 245
243 246 ``InteractiveShell.prompt_out=<string>``
244 247 String used for output prompts, also uses numbers like
245 248 prompt_in1. Default: 'Out[\#]:'
246 249
247 250 ``--quick``
248 251 start in bare bones mode (no config file loaded).
249 252
250 253 ``config_file=<name>``
251 254 name of your IPython resource configuration file. Normally
252 255 IPython loads ipython_config.py (from current directory) or
253 256 IPYTHON_DIR/profile_default.
254 257
255 258 If the loading of your config file fails, IPython starts with
256 259 a bare bones configuration (no modules loaded at all).
257 260
258 261 ``--[no-]readline``
259 262 use the readline library, which is needed to support name
260 263 completion and command history, among other things. It is
261 264 enabled by default, but may cause problems for users of
262 265 X/Emacs in Python comint or shell buffers.
263 266
264 267 Note that X/Emacs 'eterm' buffers (opened with M-x term) support
265 268 IPython's readline and syntax coloring fine, only 'emacs' (M-x
266 269 shell and C-c !) buffers do not.
267 270
268 271 ``--TerminalInteractiveShell.screen_length=<n>``
269 272 number of lines of your screen. This is used to control
270 273 printing of very long strings. Strings longer than this number
271 274 of lines will be sent through a pager instead of directly
272 275 printed.
273 276
274 277 The default value for this is 0, which means IPython will
275 278 auto-detect your screen size every time it needs to print certain
276 279 potentially long strings (this doesn't change the behavior of the
277 280 'print' keyword, it's only triggered internally). If for some
278 281 reason this isn't working well (it needs curses support), specify
279 282 it yourself. Otherwise don't change the default.
280 283
281 284 ``--TerminalInteractiveShell.separate_in=<string>``
282 285
283 286 separator before input prompts.
284 287 Default: '\n'
285 288
286 289 ``--TerminalInteractiveShell.separate_out=<string>``
287 290 separator before output prompts.
288 291 Default: nothing.
289 292
290 293 ``--TerminalInteractiveShell.separate_out2=<string>``
291 294 separator after output prompts.
292 295 Default: nothing.
293 296 For these three options, use the value 0 to specify no separator.
294 297
295 298 ``--nosep``
296 299 shorthand for setting the above separators to empty strings.
297 300
298 301 Simply removes all input/output separators.
299 302
300 303 ``--init``
301 304 allows you to initialize a profile dir for configuration when you
302 305 install a new version of IPython or want to use a new profile.
303 306 Since new versions may include new command line options or example
304 307 files, this copies updated config files. Note that you should probably
305 308 use %upgrade instead,it's a safer alternative.
306 309
307 310 ``--version`` print version information and exit.
308 311
309 312 ``--xmode=<modename>``
310 313
311 314 Mode for exception reporting.
312 315
313 316 Valid modes: Plain, Context and Verbose.
314 317
315 318 * Plain: similar to python's normal traceback printing.
316 319 * Context: prints 5 lines of context source code around each
317 320 line in the traceback.
318 321 * Verbose: similar to Context, but additionally prints the
319 322 variables currently visible where the exception happened
320 323 (shortening their strings if too long). This can potentially be
321 324 very slow, if you happen to have a huge data structure whose
322 325 string representation is complex to compute. Your computer may
323 326 appear to freeze for a while with cpu usage at 100%. If this
324 327 occurs, you can cancel the traceback with Ctrl-C (maybe hitting it
325 328 more than once).
326 329
327 330 Interactive use
328 331 ===============
329 332
330 333 IPython is meant to work as a drop-in replacement for the standard interactive
331 334 interpreter. As such, any code which is valid python should execute normally
332 335 under IPython (cases where this is not true should be reported as bugs). It
333 336 does, however, offer many features which are not available at a standard python
334 337 prompt. What follows is a list of these.
335 338
336 339
337 340 Caution for Windows users
338 341 -------------------------
339 342
340 343 Windows, unfortunately, uses the '\\' character as a path separator. This is a
341 344 terrible choice, because '\\' also represents the escape character in most
342 345 modern programming languages, including Python. For this reason, using '/'
343 346 character is recommended if you have problems with ``\``. However, in Windows
344 347 commands '/' flags options, so you can not use it for the root directory. This
345 348 means that paths beginning at the root must be typed in a contrived manner
346 349 like: ``%copy \opt/foo/bar.txt \tmp``
347 350
348 351 .. _magic:
349 352
350 353 Magic command system
351 354 --------------------
352 355
353 356 IPython will treat any line whose first character is a % as a special
354 357 call to a 'magic' function. These allow you to control the behavior of
355 358 IPython itself, plus a lot of system-type features. They are all
356 359 prefixed with a % character, but parameters are given without
357 360 parentheses or quotes.
358 361
359 362 Example: typing ``%cd mydir`` changes your working directory to 'mydir', if it
360 363 exists.
361 364
362 365 If you have 'automagic' enabled (as it by default), you don't need
363 366 to type in the % explicitly. IPython will scan its internal list of
364 367 magic functions and call one if it exists. With automagic on you can
365 368 then just type ``cd mydir`` to go to directory 'mydir'. The automagic
366 369 system has the lowest possible precedence in name searches, so defining
367 370 an identifier with the same name as an existing magic function will
368 371 shadow it for automagic use. You can still access the shadowed magic
369 372 function by explicitly using the % character at the beginning of the line.
370 373
371 374 An example (with automagic on) should clarify all this:
372 375
373 376 .. sourcecode:: ipython
374 377
375 In [1]: cd ipython # %cd is called by automagic
376
378 In [1]: cd ipython # %cd is called by automagic
377 379 /home/fperez/ipython
378 380
379 In [2]: cd=1 # now cd is just a variable
380
381 In [3]: cd .. # and doesn't work as a function anymore
382
383 ------------------------------
384
385 File "<console>", line 1
386
387 cd ..
388
389 ^
381 In [2]: cd=1 # now cd is just a variable
390 382
383 In [3]: cd .. # and doesn't work as a function anymore
384 File "<ipython-input-3-9fedb3aff56c>", line 1
385 cd ..
386 ^
391 387 SyntaxError: invalid syntax
392 388
393 In [4]: %cd .. # but %cd always works
394 389
390 In [4]: %cd .. # but %cd always works
395 391 /home/fperez
396 392
397 In [5]: del cd # if you remove the cd variable
393 In [5]: del cd # if you remove the cd variable, automagic works again
398 394
399 In [6]: cd ipython # automagic can work again
395 In [6]: cd ipython
400 396
401 397 /home/fperez/ipython
402 398
403 399 You can define your own magic functions to extend the system. The
404 400 following example defines a new magic command, %impall:
405 401
406 402 .. sourcecode:: python
407 403
408 404 ip = get_ipython()
409 405
410 406 def doimp(self, arg):
411
412 407 ip = self.api
408 ip.ex("import %s; reload(%s); from %s import *" % (arg,arg,arg) )
413 409
414 ip.ex("import %s; reload(%s); from %s import *" % (
415
416 arg,arg,arg)
417
418 )
410 ip.define_magic('impall', doimp)
419 411
420 ip.expose_magic('impall', doimp)
421
422 Type `%magic` for more information, including a list of all available magic
412 Type ``%magic`` for more information, including a list of all available magic
423 413 functions at any time and their docstrings. You can also type
424 %magic_function_name? (see :ref:`below <dynamic_object_info` for information on
414 ``%magic_function_name?`` (see :ref:`below <dynamic_object_info>` for information on
425 415 the '?' system) to get information about any particular magic function you are
426 416 interested in.
427 417
428 418 The API documentation for the :mod:`IPython.core.magic` module contains the full
429 419 docstrings of all currently available magic commands.
430 420
431 421
432 422 Access to the standard Python help
433 423 ----------------------------------
434 424
435 As of Python 2.1, a help system is available with access to object docstrings
436 and the Python manuals. Simply type 'help' (no quotes) to access it. You can
437 also type help(object) to obtain information about a given object, and
438 help('keyword') for information on a keyword. As noted :ref:`here
439 <accessing_help>`, you need to properly configure your environment variable
440 PYTHONDOCS for this feature to work correctly.
425 Simply type ``help()`` to access Python's standard help system. You can
426 also type ``help(object)`` for information about a given object, or
427 ``help('keyword')`` for information on a keyword. You may need to configure your
428 PYTHONDOCS environment variable for this feature to work correctly.
441 429
442 430 .. _dynamic_object_info:
443 431
444 432 Dynamic object information
445 433 --------------------------
446 434
447 435 Typing ``?word`` or ``word?`` prints detailed information about an object. If
448 certain strings in the object are too long (docstrings, code, etc.) they get
436 certain strings in the object are too long (e.g. function signatures) they get
449 437 snipped in the center for brevity. This system gives access variable types and
450 values, full source code for any object (if available), function prototypes and
451 other useful information.
438 values, docstrings, function prototypes and other useful information.
439
440 If the information will not fit in the terminal, it is displayed in a pager
441 (``less`` if available, otherwise a basic internal pager).
452 442
453 Typing ``??word`` or ``word??`` gives access to the full information without
454 snipping long strings. Long strings are sent to the screen through the
455 less pager if longer than the screen and printed otherwise. On systems
456 lacking the less command, IPython uses a very basic internal pager.
443 Typing ``??word`` or ``word??`` gives access to the full information, including
444 the source code where possible. Long strings are not snipped.
457 445
458 446 The following magic functions are particularly useful for gathering
459 447 information about your working environment. You can get more details by
460 typing ``%magic`` or querying them individually (use %function_name? with or
461 without the %), this is just a summary:
448 typing ``%magic`` or querying them individually (``%function_name?``);
449 this is just a summary:
462 450
463 451 * **%pdoc <object>**: Print (or run through a pager if too long) the
464 452 docstring for an object. If the given object is a class, it will
465 453 print both the class and the constructor docstrings.
466 454 * **%pdef <object>**: Print the definition header for any callable
467 455 object. If the object is a class, print the constructor information.
468 456 * **%psource <object>**: Print (or run through a pager if too long)
469 457 the source code for an object.
470 458 * **%pfile <object>**: Show the entire source file where an object was
471 459 defined via a pager, opening it at the line where the object
472 460 definition begins.
473 461 * **%who/%whos**: These functions give information about identifiers
474 462 you have defined interactively (not things you loaded or defined
475 463 in your configuration files). %who just prints a list of
476 464 identifiers and %whos prints a table with some basic details about
477 465 each identifier.
478 466
479 467 Note that the dynamic object information functions (?/??, ``%pdoc``,
480 ``%pfile``, ``%pdef``, ``%psource``) give you access to documentation even on
481 things which are not really defined as separate identifiers. Try for example
482 typing {}.get? or after doing import os, type ``os.path.abspath??``.
468 ``%pfile``, ``%pdef``, ``%psource``) work on object attributes, as well as
469 directly on variables. For example, after doing ``import os``, you can use
470 ``os.path.abspath??``.
483 471
484 472 .. _readline:
485 473
486 474 Readline-based features
487 475 -----------------------
488 476
489 477 These features require the GNU readline library, so they won't work if your
490 478 Python installation lacks readline support. We will first describe the default
491 479 behavior IPython uses, and then how to change it to suit your preferences.
492 480
493 481
494 482 Command line completion
495 483 +++++++++++++++++++++++
496 484
497 485 At any time, hitting TAB will complete any available python commands or
498 486 variable names, and show you a list of the possible completions if
499 487 there's no unambiguous one. It will also complete filenames in the
500 488 current directory if no python names match what you've typed so far.
501 489
502 490
503 491 Search command history
504 492 ++++++++++++++++++++++
505 493
506 494 IPython provides two ways for searching through previous input and thus
507 495 reduce the need for repetitive typing:
508 496
509 497 1. Start typing, and then use Ctrl-p (previous,up) and Ctrl-n
510 498 (next,down) to search through only the history items that match
511 499 what you've typed so far. If you use Ctrl-p/Ctrl-n at a blank
512 500 prompt, they just behave like normal arrow keys.
513 501 2. Hit Ctrl-r: opens a search prompt. Begin typing and the system
514 502 searches your history for lines that contain what you've typed so
515 503 far, completing as much as it can.
516 504
517 505
518 506 Persistent command history across sessions
519 507 ++++++++++++++++++++++++++++++++++++++++++
520 508
521 509 IPython will save your input history when it leaves and reload it next
522 510 time you restart it. By default, the history file is named
523 511 $IPYTHON_DIR/profile_<name>/history.sqlite. This allows you to keep
524 512 separate histories related to various tasks: commands related to
525 513 numerical work will not be clobbered by a system shell history, for
526 514 example.
527 515
528 516
529 517 Autoindent
530 518 ++++++++++
531 519
532 520 IPython can recognize lines ending in ':' and indent the next line,
533 521 while also un-indenting automatically after 'raise' or 'return'.
534 522
535 523 This feature uses the readline library, so it will honor your
536 524 :file:`~/.inputrc` configuration (or whatever file your INPUTRC variable points
537 525 to). Adding the following lines to your :file:`.inputrc` file can make
538 526 indenting/unindenting more convenient (M-i indents, M-u unindents)::
539 527
540 528 $if Python
541 529 "\M-i": " "
542 530 "\M-u": "\d\d\d\d"
543 531 $endif
544 532
545 533 Note that there are 4 spaces between the quote marks after "M-i" above.
546 534
547 535 .. warning::
548 536
549 537 Setting the above indents will cause problems with unicode text entry in
550 538 the terminal.
551 539
552 540 .. warning::
553 541
554 542 Autoindent is ON by default, but it can cause problems with the pasting of
555 543 multi-line indented code (the pasted code gets re-indented on each line). A
556 544 magic function %autoindent allows you to toggle it on/off at runtime. You
557 545 can also disable it permanently on in your :file:`ipython_config.py` file
558 546 (set TerminalInteractiveShell.autoindent=False).
559 547
560 If you want to paste multiple lines, it is recommended that you use
561 ``%paste``.
548 If you want to paste multiple lines in the terminal, it is recommended that
549 you use ``%paste``.
562 550
563 551
564 552 Customizing readline behavior
565 553 +++++++++++++++++++++++++++++
566 554
567 555 All these features are based on the GNU readline library, which has an
568 556 extremely customizable interface. Normally, readline is configured via a
569 557 file which defines the behavior of the library; the details of the
570 558 syntax for this can be found in the readline documentation available
571 559 with your system or on the Internet. IPython doesn't read this file (if
572 560 it exists) directly, but it does support passing to readline valid
573 561 options via a simple interface. In brief, you can customize readline by
574 562 setting the following options in your configuration file (note
575 563 that these options can not be specified at the command line):
576 564
577 * **readline_parse_and_bind**: this option can appear as many times as
578 you want, each time defining a string to be executed via a
579 readline.parse_and_bind() command. The syntax for valid commands
565 * **readline_parse_and_bind**: this holds a list of strings to be executed
566 via a readline.parse_and_bind() command. The syntax for valid commands
580 567 of this kind can be found by reading the documentation for the GNU
581 568 readline library, as these commands are of the kind which readline
582 569 accepts in its configuration file.
583 570 * **readline_remove_delims**: a string of characters to be removed
584 571 from the default word-delimiters list used by readline, so that
585 572 completions may be performed on strings which contain them. Do not
586 573 change the default value unless you know what you're doing.
587 * **readline_omit__names**: when tab-completion is enabled, hitting
588 <tab> after a '.' in a name will complete all attributes of an
589 object, including all the special methods whose names include
590 double underscores (like __getitem__ or __class__). If you'd
591 rather not see these names by default, you can set this option to
592 1. Note that even when this option is set, you can still see those
593 names by explicitly typing a _ after the period and hitting <tab>:
594 'name._<tab>' will always complete attribute names starting with '_'.
595
596 This option is off by default so that new users see all
597 attributes of any objects they are dealing with.
598 574
599 575 You will find the default values in your configuration file.
600 576
601 577
602 578 Session logging and restoring
603 579 -----------------------------
604 580
605 581 You can log all input from a session either by starting IPython with the
606 582 command line switch ``--logfile=foo.py`` (see :ref:`here <command_line_options>`)
607 583 or by activating the logging at any moment with the magic function %logstart.
608 584
609 585 Log files can later be reloaded by running them as scripts and IPython
610 586 will attempt to 'replay' the log by executing all the lines in it, thus
611 587 restoring the state of a previous session. This feature is not quite
612 588 perfect, but can still be useful in many cases.
613 589
614 590 The log files can also be used as a way to have a permanent record of
615 591 any code you wrote while experimenting. Log files are regular text files
616 592 which you can later open in your favorite text editor to extract code or
617 593 to 'clean them up' before using them to replay a session.
618 594
619 595 The `%logstart` function for activating logging in mid-session is used as
620 596 follows::
621 597
622 598 %logstart [log_name [log_mode]]
623 599
624 600 If no name is given, it defaults to a file named 'ipython_log.py' in your
625 601 current working directory, in 'rotate' mode (see below).
626 602
627 603 '%logstart name' saves to file 'name' in 'backup' mode. It saves your
628 604 history up to that point and then continues logging.
629 605
630 606 %logstart takes a second optional parameter: logging mode. This can be
631 607 one of (note that the modes are given unquoted):
632 608
633 609 * [over:] overwrite existing log_name.
634 610 * [backup:] rename (if exists) to log_name~ and start log_name.
635 611 * [append:] well, that says it.
636 612 * [rotate:] create rotating logs log_name.1~, log_name.2~, etc.
637 613
638 614 The %logoff and %logon functions allow you to temporarily stop and
639 615 resume logging to a file which had previously been started with
640 616 %logstart. They will fail (with an explanation) if you try to use them
641 617 before logging has been started.
642 618
643 619 .. _system_shell_access:
644 620
645 621 System shell access
646 622 -------------------
647 623
648 624 Any input line beginning with a ! character is passed verbatim (minus
649 625 the !, of course) to the underlying operating system. For example,
650 626 typing ``!ls`` will run 'ls' in the current directory.
651 627
652 628 Manual capture of command output
653 629 --------------------------------
654 630
655 631 You can assign the result of a system command to a Python variable with the
656 632 syntax ``myfiles = !ls``. This gets machine readable output from stdout
657 633 (e.g. without colours), and splits on newlines. To explicitly get this sort of
658 634 output without assigning to a variable, use two exclamation marks (``!!ls``) or
659 635 the ``%sx`` magic command.
660 636
661 637 The captured list has some convenience features. ``myfiles.n`` or ``myfiles.s``
662 638 returns a string delimited by newlines or spaces, respectively. ``myfiles.p``
663 639 produces `path objects <http://pypi.python.org/pypi/path.py>`_ from the list items.
664 640
665 641 IPython also allows you to expand the value of python variables when
666 642 making system calls. Wrap variables or expressions in {braces}::
667 643
668 644 In [1]: pyvar = 'Hello world'
669 645 In [2]: !echo "A python variable: {pyvar}"
670 646 A python variable: Hello world
671 647 In [3]: import math
672 648 In [4]: x = 8
673 649 In [5]: !echo {math.factorial(x)}
674 650 40320
675 651
676 652 For simple cases, you can alternatively prepend $ to a variable name::
677 653
678 654 In [6]: !echo $sys.argv
679 655 [/home/fperez/usr/bin/ipython]
680 656 In [7]: !echo "A system variable: $$HOME" # Use $$ for literal $
681 657 A system variable: /home/fperez
682 658
683 659 System command aliases
684 660 ----------------------
685 661
686 662 The %alias magic function allows you to define magic functions which are in fact
687 663 system shell commands. These aliases can have parameters.
688 664
689 665 ``%alias alias_name cmd`` defines 'alias_name' as an alias for 'cmd'
690 666
691 Then, typing ``%alias_name params`` will execute the system command 'cmd
667 Then, typing ``alias_name params`` will execute the system command 'cmd
692 668 params' (from your underlying operating system).
693 669
694 670 You can also define aliases with parameters using %s specifiers (one per
695 parameter). The following example defines the %parts function as an
671 parameter). The following example defines the parts function as an
696 672 alias to the command 'echo first %s second %s' where each %s will be
697 673 replaced by a positional parameter to the call to %parts::
698 674
699 In [1]: alias parts echo first %s second %s
700 In [2]: %parts A B
701 first A second B
702 In [3]: %parts A
703 Incorrect number of arguments: 2 expected.
704 parts is an alias to: 'echo first %s second %s'
675 In [1]: %alias parts echo first %s second %s
676 In [2]: parts A B
677 first A second B
678 In [3]: parts A
679 ERROR: Alias <parts> requires 2 arguments, 1 given.
705 680
706 681 If called with no parameters, %alias prints the table of currently
707 682 defined aliases.
708 683
709 684 The %rehashx magic allows you to load your entire $PATH as
710 685 ipython aliases. See its docstring for further details.
711 686
712 687
713 688 .. _dreload:
714 689
715 690 Recursive reload
716 691 ----------------
717 692
718 The dreload function does a recursive reload of a module: changes made
719 to the module since you imported will actually be available without
720 having to exit.
693 The :mod:`IPython.lib.deepreload` module allows you to recursively reload a
694 module: changes made to any of its dependencies will be reloaded without
695 having to exit. To start using it, do::
696
697 from IPython.lib.deepreload import reload as dreload
721 698
722 699
723 700 Verbose and colored exception traceback printouts
724 701 -------------------------------------------------
725 702
726 703 IPython provides the option to see very detailed exception tracebacks,
727 704 which can be especially useful when debugging large programs. You can
728 705 run any Python file with the %run function to benefit from these
729 706 detailed tracebacks. Furthermore, both normal and verbose tracebacks can
730 707 be colored (if your terminal supports it) which makes them much easier
731 708 to parse visually.
732 709
733 710 See the magic xmode and colors functions for details (just type %magic).
734 711
735 712 These features are basically a terminal version of Ka-Ping Yee's cgitb
736 713 module, now part of the standard Python library.
737 714
738 715
739 716 .. _input_caching:
740 717
741 718 Input caching system
742 719 --------------------
743 720
744 721 IPython offers numbered prompts (In/Out) with input and output caching
745 722 (also referred to as 'input history'). All input is saved and can be
746 723 retrieved as variables (besides the usual arrow key recall), in
747 724 addition to the %rep magic command that brings a history entry
748 725 up for editing on the next command line.
749 726
750 727 The following GLOBAL variables always exist (so don't overwrite them!):
751 728
752 729 * _i, _ii, _iii: store previous, next previous and next-next previous inputs.
753 730 * In, _ih : a list of all inputs; _ih[n] is the input from line n. If you
754 731 overwrite In with a variable of your own, you can remake the assignment to the
755 732 internal list with a simple ``In=_ih``.
756 733
757 734 Additionally, global variables named _i<n> are dynamically created (<n>
758 735 being the prompt counter), so ``_i<n> == _ih[<n>] == In[<n>]``.
759 736
760 737 For example, what you typed at prompt 14 is available as _i14, _ih[14]
761 738 and In[14].
762 739
763 740 This allows you to easily cut and paste multi line interactive prompts
764 741 by printing them out: they print like a clean string, without prompt
765 742 characters. You can also manipulate them like regular variables (they
766 743 are strings), modify or exec them (typing ``exec _i9`` will re-execute the
767 744 contents of input prompt 9.
768 745
769 746 You can also re-execute multiple lines of input easily by using the
770 magic %macro function (which automates the process and allows
771 re-execution without having to type 'exec' every time). The macro system
772 also allows you to re-execute previous lines which include magic
773 function calls (which require special processing). Type %macro? for more details
774 on the macro system.
747 magic %rerun or %macro functions. The macro system also allows you to re-execute
748 previous lines which include magic function calls (which require special
749 processing). Type %macro? for more details on the macro system.
775 750
776 751 A history function %hist allows you to see any part of your input
777 752 history by printing a range of the _i variables.
778 753
779 754 You can also search ('grep') through your history by typing
780 755 ``%hist -g somestring``. This is handy for searching for URLs, IP addresses,
781 756 etc. You can bring history entries listed by '%hist -g' up for editing
782 757 with the %recall command, or run them immediately with %rerun.
783 758
784 759 .. _output_caching:
785 760
786 761 Output caching system
787 762 ---------------------
788 763
789 764 For output that is returned from actions, a system similar to the input
790 765 cache exists but using _ instead of _i. Only actions that produce a
791 766 result (NOT assignments, for example) are cached. If you are familiar
792 767 with Mathematica, IPython's _ variables behave exactly like
793 768 Mathematica's % variables.
794 769
795 770 The following GLOBAL variables always exist (so don't overwrite them!):
796 771
797 772 * [_] (a single underscore) : stores previous output, like Python's
798 773 default interpreter.
799 774 * [__] (two underscores): next previous.
800 775 * [___] (three underscores): next-next previous.
801 776
802 777 Additionally, global variables named _<n> are dynamically created (<n>
803 778 being the prompt counter), such that the result of output <n> is always
804 779 available as _<n> (don't use the angle brackets, just the number, e.g.
805 780 _21).
806 781
807 These global variables are all stored in a global dictionary (not a
782 These variables are also stored in a global dictionary (not a
808 783 list, since it only has entries for lines which returned a result)
809 784 available under the names _oh and Out (similar to _ih and In). So the
810 785 output from line 12 can be obtained as _12, Out[12] or _oh[12]. If you
811 786 accidentally overwrite the Out variable you can recover it by typing
812 787 'Out=_oh' at the prompt.
813 788
814 789 This system obviously can potentially put heavy memory demands on your
815 790 system, since it prevents Python's garbage collector from removing any
816 791 previously computed results. You can control how many results are kept
817 792 in memory with the option (at the command line or in your configuration
818 793 file) cache_size. If you set it to 0, the whole system is completely
819 794 disabled and the prompts revert to the classic '>>>' of normal Python.
820 795
821 796
822 797 Directory history
823 798 -----------------
824 799
825 800 Your history of visited directories is kept in the global list _dh, and
826 801 the magic %cd command can be used to go to any entry in that list. The
827 802 %dhist command allows you to view this history. Do ``cd -<TAB>`` to
828 803 conveniently view the directory history.
829 804
830 805
831 806 Automatic parentheses and quotes
832 807 --------------------------------
833 808
834 809 These features were adapted from Nathan Gray's LazyPython. They are
835 810 meant to allow less typing for common situations.
836 811
837 812
838 813 Automatic parentheses
839 ---------------------
814 +++++++++++++++++++++
840 815
841 816 Callable objects (i.e. functions, methods, etc) can be invoked like this
842 817 (notice the commas between the arguments)::
843 818
844 >>> callable_ob arg1, arg2, arg3
845
846 and the input will be translated to this::
847
848 -> callable_ob(arg1, arg2, arg3)
819 In [1]: callable_ob arg1, arg2, arg3
820 ------> callable_ob(arg1, arg2, arg3)
849 821
850 822 You can force automatic parentheses by using '/' as the first character
851 823 of a line. For example::
852 824
853 >>> /globals # becomes 'globals()'
825 In [2]: /globals # becomes 'globals()'
854 826
855 827 Note that the '/' MUST be the first character on the line! This won't work::
856 828
857 >>> print /globals # syntax error
829 In [3]: print /globals # syntax error
858 830
859 831 In most cases the automatic algorithm should work, so you should rarely
860 832 need to explicitly invoke /. One notable exception is if you are trying
861 833 to call a function with a list of tuples as arguments (the parenthesis
862 834 will confuse IPython)::
863 835
864 In [1]: zip (1,2,3),(4,5,6) # won't work
836 In [4]: zip (1,2,3),(4,5,6) # won't work
865 837
866 838 but this will work::
867 839
868 In [2]: /zip (1,2,3),(4,5,6)
869 ---> zip ((1,2,3),(4,5,6))
870 Out[2]= [(1, 4), (2, 5), (3, 6)]
840 In [5]: /zip (1,2,3),(4,5,6)
841 ------> zip ((1,2,3),(4,5,6))
842 Out[5]: [(1, 4), (2, 5), (3, 6)]
871 843
872 844 IPython tells you that it has altered your command line by displaying
873 845 the new command line preceded by ->. e.g.::
874 846
875 In [18]: callable list
876 ----> callable (list)
847 In [6]: callable list
848 ------> callable(list)
877 849
878 850
879 851 Automatic quoting
880 -----------------
852 +++++++++++++++++
881 853
882 854 You can force automatic quoting of a function's arguments by using ','
883 855 or ';' as the first character of a line. For example::
884 856
885 >>> ,my_function /home/me # becomes my_function("/home/me")
857 In [1]: ,my_function /home/me # becomes my_function("/home/me")
886 858
887 If you use ';' instead, the whole argument is quoted as a single string
888 (while ',' splits on whitespace)::
859 If you use ';' the whole argument is quoted as a single string, while ',' splits
860 on whitespace::
889 861
890 >>> ,my_function a b c # becomes my_function("a","b","c")
862 In [2]: ,my_function a b c # becomes my_function("a","b","c")
891 863
892 >>> ;my_function a b c # becomes my_function("a b c")
864 In [3]: ;my_function a b c # becomes my_function("a b c")
893 865
894 866 Note that the ',' or ';' MUST be the first character on the line! This
895 867 won't work::
896 868
897 >>> x = ,my_function /home/me # syntax error
869 In [4]: x = ,my_function /home/me # syntax error
898 870
899 871 IPython as your default Python environment
900 872 ==========================================
901 873
902 874 Python honors the environment variable PYTHONSTARTUP and will execute at
903 startup the file referenced by this variable. If you put at the end of
904 this file the following two lines of code::
875 startup the file referenced by this variable. If you put the following code at
876 the end of that file, then IPython will be your working environment anytime you
877 start Python::
905 878
906 879 from IPython.frontend.terminal.ipapp import launch_new_instance
907 880 launch_new_instance()
908 881 raise SystemExit
909 882
910 then IPython will be your working environment anytime you start Python.
911 883 The ``raise SystemExit`` is needed to exit Python when
912 884 it finishes, otherwise you'll be back at the normal Python '>>>'
913 885 prompt.
914 886
915 887 This is probably useful to developers who manage multiple Python
916 888 versions and don't want to have correspondingly multiple IPython
917 889 versions. Note that in this mode, there is no way to pass IPython any
918 890 command-line options, as those are trapped first by Python itself.
919 891
920 892 .. _Embedding:
921 893
922 894 Embedding IPython
923 895 =================
924 896
925 897 It is possible to start an IPython instance inside your own Python
926 898 programs. This allows you to evaluate dynamically the state of your
927 899 code, operate with your variables, analyze them, etc. Note however that
928 900 any changes you make to values while in the shell do not propagate back
929 901 to the running code, so it is safe to modify your values because you
930 902 won't break your code in bizarre ways by doing so.
931 903
904 .. note::
905
906 At present, trying to embed IPython from inside IPython causes problems. Run
907 the code samples below outside IPython.
908
932 909 This feature allows you to easily have a fully functional python
933 910 environment for doing object introspection anywhere in your code with a
934 911 simple function call. In some cases a simple print statement is enough,
935 912 but if you need to do more detailed analysis of a code fragment this
936 913 feature can be very valuable.
937 914
938 915 It can also be useful in scientific computing situations where it is
939 916 common to need to do some automatic, computationally intensive part and
940 917 then stop to look at data, plots, etc.
941 918 Opening an IPython instance will give you full access to your data and
942 919 functions, and you can resume program execution once you are done with
943 920 the interactive part (perhaps to stop again later, as many times as
944 921 needed).
945 922
946 923 The following code snippet is the bare minimum you need to include in
947 924 your Python programs for this to work (detailed examples follow later)::
948 925
949 926 from IPython import embed
950 927
951 928 embed() # this call anywhere in your program will start IPython
952 929
953 930 You can run embedded instances even in code which is itself being run at
954 931 the IPython interactive prompt with '%run <filename>'. Since it's easy
955 932 to get lost as to where you are (in your top-level IPython or in your
956 933 embedded one), it's a good idea in such cases to set the in/out prompts
957 934 to something different for the embedded instances. The code examples
958 935 below illustrate this.
959 936
960 937 You can also have multiple IPython instances in your program and open
961 938 them separately, for example with different options for data
962 939 presentation. If you close and open the same instance multiple times,
963 940 its prompt counters simply continue from each execution to the next.
964 941
965 942 Please look at the docstrings in the :mod:`~IPython.frontend.terminal.embed`
966 943 module for more details on the use of this system.
967 944
968 945 The following sample file illustrating how to use the embedding
969 946 functionality is provided in the examples directory as example-embed.py.
970 947 It should be fairly self-explanatory:
971 948
972 949 .. literalinclude:: ../../examples/core/example-embed.py
973 950 :language: python
974 951
975 952 Once you understand how the system functions, you can use the following
976 953 code fragments in your programs which are ready for cut and paste:
977 954
978 955 .. literalinclude:: ../../examples/core/example-embed-short.py
979 956 :language: python
980 957
981 958 Using the Python debugger (pdb)
982 959 ===============================
983 960
984 961 Running entire programs via pdb
985 962 -------------------------------
986 963
987 964 pdb, the Python debugger, is a powerful interactive debugger which
988 965 allows you to step through code, set breakpoints, watch variables,
989 966 etc. IPython makes it very easy to start any script under the control
990 967 of pdb, regardless of whether you have wrapped it into a 'main()'
991 968 function or not. For this, simply type '%run -d myscript' at an
992 969 IPython prompt. See the %run command's documentation (via '%run?' or
993 970 in Sec. magic_ for more details, including how to control where pdb
994 971 will stop execution first.
995 972
996 973 For more information on the use of the pdb debugger, read the included
997 974 pdb.doc file (part of the standard Python distribution). On a stock
998 975 Linux system it is located at /usr/lib/python2.3/pdb.doc, but the
999 976 easiest way to read it is by using the help() function of the pdb module
1000 977 as follows (in an IPython prompt)::
1001 978
1002 979 In [1]: import pdb
1003 980 In [2]: pdb.help()
1004 981
1005 982 This will load the pdb.doc document in a file viewer for you automatically.
1006 983
1007 984
1008 985 Automatic invocation of pdb on exceptions
1009 986 -----------------------------------------
1010 987
1011 IPython, if started with the -pdb option (or if the option is set in
1012 your rc file) can call the Python pdb debugger every time your code
988 IPython, if started with the ``--pdb`` option (or if the option is set in
989 your config file) can call the Python pdb debugger every time your code
1013 990 triggers an uncaught exception. This feature
1014 991 can also be toggled at any time with the %pdb magic command. This can be
1015 992 extremely useful in order to find the origin of subtle bugs, because pdb
1016 993 opens up at the point in your code which triggered the exception, and
1017 994 while your program is at this point 'dead', all the data is still
1018 995 available and you can walk up and down the stack frame and understand
1019 996 the origin of the problem.
1020 997
1021 998 Furthermore, you can use these debugging facilities both with the
1022 999 embedded IPython mode and without IPython at all. For an embedded shell
1023 1000 (see sec. Embedding_), simply call the constructor with
1024 '--pdb' in the argument string and automatically pdb will be called if an
1001 ``--pdb`` in the argument string and pdb will automatically be called if an
1025 1002 uncaught exception is triggered by your code.
1026 1003
1027 1004 For stand-alone use of the feature in your programs which do not use
1028 1005 IPython at all, put the following lines toward the top of your 'main'
1029 1006 routine::
1030 1007
1031 1008 import sys
1032 1009 from IPython.core import ultratb
1033 1010 sys.excepthook = ultratb.FormattedTB(mode='Verbose',
1034 1011 color_scheme='Linux', call_pdb=1)
1035 1012
1036 1013 The mode keyword can be either 'Verbose' or 'Plain', giving either very
1037 1014 detailed or normal tracebacks respectively. The color_scheme keyword can
1038 1015 be one of 'NoColor', 'Linux' (default) or 'LightBG'. These are the same
1039 options which can be set in IPython with -colors and -xmode.
1016 options which can be set in IPython with ``--colors`` and ``--xmode``.
1040 1017
1041 1018 This will give any of your programs detailed, colored tracebacks with
1042 1019 automatic invocation of pdb.
1043 1020
1044 1021
1045 1022 Extensions for syntax processing
1046 1023 ================================
1047 1024
1048 1025 This isn't for the faint of heart, because the potential for breaking
1049 1026 things is quite high. But it can be a very powerful and useful feature.
1050 1027 In a nutshell, you can redefine the way IPython processes the user input
1051 1028 line to accept new, special extensions to the syntax without needing to
1052 1029 change any of IPython's own code.
1053 1030
1054 1031 In the IPython/extensions directory you will find some examples
1055 1032 supplied, which we will briefly describe now. These can be used 'as is'
1056 1033 (and both provide very useful functionality), or you can use them as a
1057 1034 starting point for writing your own extensions.
1058 1035
1059 1036 .. _pasting_with_prompts:
1060 1037
1061 1038 Pasting of code starting with Python or IPython prompts
1062 1039 -------------------------------------------------------
1063 1040
1064 1041 IPython is smart enough to filter out input prompts, be they plain Python ones
1065 1042 (``>>>`` and ``...``) or IPython ones (``In [N]:`` and `` ...:``). You can
1066 1043 therefore copy and paste from existing interactive sessions without worry.
1067 1044
1068 1045 The following is a 'screenshot' of how things work, copying an example from the
1069 1046 standard Python tutorial::
1070 1047
1071 1048 In [1]: >>> # Fibonacci series:
1072 1049
1073 1050 In [2]: ... # the sum of two elements defines the next
1074 1051
1075 1052 In [3]: ... a, b = 0, 1
1076 1053
1077 1054 In [4]: >>> while b < 10:
1078 1055 ...: ... print b
1079 1056 ...: ... a, b = b, a+b
1080 1057 ...:
1081 1058 1
1082 1059 1
1083 1060 2
1084 1061 3
1085 1062 5
1086 1063 8
1087 1064
1088 1065 And pasting from IPython sessions works equally well::
1089 1066
1090 1067 In [1]: In [5]: def f(x):
1091 1068 ...: ...: "A simple function"
1092 1069 ...: ...: return x**2
1093 1070 ...: ...:
1094 1071
1095 1072 In [2]: f(3)
1096 1073 Out[2]: 9
1097 1074
1098 1075 .. _gui_support:
1099 1076
1100 1077 GUI event loop support
1101 1078 ======================
1102 1079
1103 1080 .. versionadded:: 0.11
1104 1081 The ``%gui`` magic and :mod:`IPython.lib.inputhook`.
1105 1082
1106 1083 IPython has excellent support for working interactively with Graphical User
1107 1084 Interface (GUI) toolkits, such as wxPython, PyQt4/PySide, PyGTK and Tk. This is
1108 1085 implemented using Python's builtin ``PyOSInputHook`` hook. This implementation
1109 1086 is extremely robust compared to our previous thread-based version. The
1110 1087 advantages of this are:
1111 1088
1112 1089 * GUIs can be enabled and disabled dynamically at runtime.
1113 1090 * The active GUI can be switched dynamically at runtime.
1114 1091 * In some cases, multiple GUIs can run simultaneously with no problems.
1115 1092 * There is a developer API in :mod:`IPython.lib.inputhook` for customizing
1116 1093 all of these things.
1117 1094
1118 1095 For users, enabling GUI event loop integration is simple. You simple use the
1119 1096 ``%gui`` magic as follows::
1120 1097
1121 1098 %gui [GUINAME]
1122 1099
1123 1100 With no arguments, ``%gui`` removes all GUI support. Valid ``GUINAME``
1124 1101 arguments are ``wx``, ``qt``, ``gtk`` and ``tk``.
1125 1102
1126 1103 Thus, to use wxPython interactively and create a running :class:`wx.App`
1127 1104 object, do::
1128 1105
1129 1106 %gui wx
1130 1107
1131 1108 For information on IPython's Matplotlib integration (and the ``pylab`` mode)
1132 1109 see :ref:`this section <matplotlib_support>`.
1133 1110
1134 1111 For developers that want to use IPython's GUI event loop integration in the
1135 1112 form of a library, these capabilities are exposed in library form in the
1136 1113 :mod:`IPython.lib.inputhook` and :mod:`IPython.lib.guisupport` modules.
1137 1114 Interested developers should see the module docstrings for more information,
1138 1115 but there are a few points that should be mentioned here.
1139 1116
1140 1117 First, the ``PyOSInputHook`` approach only works in command line settings
1141 1118 where readline is activated. The integration with various eventloops
1142 1119 is handled somewhat differently (and more simply) when using the standalone
1143 1120 kernel, as in the qtconsole and notebook.
1144 1121
1145 1122 Second, when using the ``PyOSInputHook`` approach, a GUI application should
1146 1123 *not* start its event loop. Instead all of this is handled by the
1147 1124 ``PyOSInputHook``. This means that applications that are meant to be used both
1148 1125 in IPython and as standalone apps need to have special code to detects how the
1149 1126 application is being run. We highly recommend using IPython's support for this.
1150 1127 Since the details vary slightly between toolkits, we point you to the various
1151 1128 examples in our source directory :file:`docs/examples/lib` that demonstrate
1152 1129 these capabilities.
1153 1130
1154 1131 .. warning::
1155 1132
1156 1133 The WX version of this is currently broken. While ``--pylab=wx`` works
1157 1134 fine, standalone WX apps do not. See
1158 1135 https://github.com/ipython/ipython/issues/645 for details of our progress on
1159 1136 this issue.
1160 1137
1161 1138
1162 1139 Third, unlike previous versions of IPython, we no longer "hijack" (replace
1163 1140 them with no-ops) the event loops. This is done to allow applications that
1164 1141 actually need to run the real event loops to do so. This is often needed to
1165 1142 process pending events at critical points.
1166 1143
1167 1144 Finally, we also have a number of examples in our source directory
1168 1145 :file:`docs/examples/lib` that demonstrate these capabilities.
1169 1146
1170 1147 PyQt and PySide
1171 1148 ---------------
1172 1149
1173 1150 .. attempt at explanation of the complete mess that is Qt support
1174 1151
1175 1152 When you use ``--gui=qt`` or ``--pylab=qt``, IPython can work with either
1176 1153 PyQt4 or PySide. There are three options for configuration here, because
1177 1154 PyQt4 has two APIs for QString and QVariant - v1, which is the default on
1178 1155 Python 2, and the more natural v2, which is the only API supported by PySide.
1179 1156 v2 is also the default for PyQt4 on Python 3. IPython's code for the QtConsole
1180 1157 uses v2, but you can still use any interface in your code, since the
1181 1158 Qt frontend is in a different process.
1182 1159
1183 1160 The default will be to import PyQt4 without configuration of the APIs, thus
1184 1161 matching what most applications would expect. It will fall back of PySide if
1185 1162 PyQt4 is unavailable.
1186 1163
1187 1164 If specified, IPython will respect the environment variable ``QT_API`` used
1188 1165 by ETS. ETS 4.0 also works with both PyQt4 and PySide, but it requires
1189 1166 PyQt4 to use its v2 API. So if ``QT_API=pyside`` PySide will be used,
1190 1167 and if ``QT_API=pyqt`` then PyQt4 will be used *with the v2 API* for
1191 1168 QString and QVariant, so ETS codes like MayaVi will also work with IPython.
1192 1169
1193 1170 If you launch IPython in pylab mode with ``ipython --pylab=qt``, then IPython
1194 1171 will ask matplotlib which Qt library to use (only if QT_API is *not set*), via
1195 1172 the 'backend.qt4' rcParam. If matplotlib is version 1.0.1 or older, then
1196 1173 IPython will always use PyQt4 without setting the v2 APIs, since neither v2
1197 1174 PyQt nor PySide work.
1198 1175
1199 1176 .. warning::
1200 1177
1201 1178 Note that this means for ETS 4 to work with PyQt4, ``QT_API`` *must* be set
1202 1179 to work with IPython's qt integration, because otherwise PyQt4 will be
1203 1180 loaded in an incompatible mode.
1204 1181
1205 1182 It also means that you must *not* have ``QT_API`` set if you want to
1206 1183 use ``--gui=qt`` with code that requires PyQt4 API v1.
1207 1184
1208 1185
1209 1186 .. _matplotlib_support:
1210 1187
1211 1188 Plotting with matplotlib
1212 1189 ========================
1213 1190
1214 1191 `Matplotlib`_ provides high quality 2D and 3D plotting for Python. Matplotlib
1215 1192 can produce plots on screen using a variety of GUI toolkits, including Tk,
1216 1193 PyGTK, PyQt4 and wxPython. It also provides a number of commands useful for
1217 1194 scientific computing, all with a syntax compatible with that of the popular
1218 1195 Matlab program.
1219 1196
1220 1197 To start IPython with matplotlib support, use the ``--pylab`` switch. If no
1221 1198 arguments are given, IPython will automatically detect your choice of
1222 1199 matplotlib backend. You can also request a specific backend with
1223 1200 ``--pylab=backend``, where ``backend`` must be one of: 'tk', 'qt', 'wx', 'gtk',
1224 1201 'osx'.
1225 1202
1226 1203 .. _Matplotlib: http://matplotlib.sourceforge.net
1227 1204
1228 1205 .. _interactive_demos:
1229 1206
1230 1207 Interactive demos with IPython
1231 1208 ==============================
1232 1209
1233 1210 IPython ships with a basic system for running scripts interactively in
1234 1211 sections, useful when presenting code to audiences. A few tags embedded
1235 1212 in comments (so that the script remains valid Python code) divide a file
1236 1213 into separate blocks, and the demo can be run one block at a time, with
1237 1214 IPython printing (with syntax highlighting) the block before executing
1238 1215 it, and returning to the interactive prompt after each block. The
1239 1216 interactive namespace is updated after each block is run with the
1240 1217 contents of the demo's namespace.
1241 1218
1242 1219 This allows you to show a piece of code, run it and then execute
1243 1220 interactively commands based on the variables just created. Once you
1244 1221 want to continue, you simply execute the next block of the demo. The
1245 1222 following listing shows the markup necessary for dividing a script into
1246 1223 sections for execution as a demo:
1247 1224
1248 1225 .. literalinclude:: ../../examples/lib/example-demo.py
1249 1226 :language: python
1250 1227
1251 1228 In order to run a file as a demo, you must first make a Demo object out
1252 1229 of it. If the file is named myscript.py, the following code will make a
1253 1230 demo::
1254 1231
1255 1232 from IPython.lib.demo import Demo
1256 1233
1257 1234 mydemo = Demo('myscript.py')
1258 1235
1259 1236 This creates the mydemo object, whose blocks you run one at a time by
1260 1237 simply calling the object with no arguments. If you have autocall active
1261 1238 in IPython (the default), all you need to do is type::
1262 1239
1263 1240 mydemo
1264 1241
1265 1242 and IPython will call it, executing each block. Demo objects can be
1266 1243 restarted, you can move forward or back skipping blocks, re-execute the
1267 1244 last block, etc. Simply use the Tab key on a demo object to see its
1268 1245 methods, and call '?' on them to see their docstrings for more usage
1269 1246 details. In addition, the demo module itself contains a comprehensive
1270 1247 docstring, which you can access via::
1271 1248
1272 1249 from IPython.lib import demo
1273 1250
1274 1251 demo?
1275 1252
1276 1253 Limitations: It is important to note that these demos are limited to
1277 fairly simple uses. In particular, you can not put division marks in
1254 fairly simple uses. In particular, you cannot break up sections within
1278 1255 indented code (loops, if statements, function definitions, etc.)
1279 1256 Supporting something like this would basically require tracking the
1280 1257 internal execution state of the Python interpreter, so only top-level
1281 1258 divisions are allowed. If you want to be able to open an IPython
1282 1259 instance at an arbitrary point in a program, you can use IPython's
1283 1260 embedding facilities, see :func:`IPython.embed` for details.
1284 1261
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