made docstrings clearer and more explicit/correct for eval and R methods

IPython/extensions/rmagic.py

@@ -1,690 +1,691
 # -*- coding: utf-8 -*-
 """
 ======
 Rmagic
 ======
 
 Magic command interface for interactive work with R via rpy2
 
 Usage
 =====
 
 ``%R``
 
 {R_DOC}
 
 ``%Rpush``
 
 {RPUSH_DOC}
 
 ``%Rpull``
 
 {RPULL_DOC}
 
 ``%Rget``
 
 {RGET_DOC}
 
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2012 The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 import sys
 import tempfile
 from glob import glob
 from shutil import rmtree
 
 # numpy and rpy2 imports
 
 import numpy as np
 
 import rpy2.rinterface as ri
 import rpy2.robjects as ro
 try:
     from rpy2.robjects import pandas2ri
     pandas2ri.activate()
 except ImportError:
     pandas2ri = None
     from rpy2.robjects import numpy2ri
     numpy2ri.activate()
 
 # IPython imports
 
 from IPython.core.displaypub import publish_display_data
 from IPython.core.magic import (Magics, magics_class, line_magic,
                                 line_cell_magic, needs_local_scope)
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.core.magic_arguments import (
     argument, magic_arguments, parse_argstring
 )
 from IPython.external.simplegeneric import generic
 from IPython.utils.py3compat import str_to_unicode, unicode_to_str, PY3
 
 class RInterpreterError(ri.RRuntimeError):
     """An error when running R code in a %%R magic cell."""
     def __init__(self, line, err, stdout):
         self.line = line
         self.err = err.rstrip()
         self.stdout = stdout.rstrip()
     
     def __unicode__(self):
         s = 'Failed to parse and evaluate line %r.\nR error message: %r' % \
                 (self.line, self.err)
         if self.stdout and (self.stdout != self.err):
             s += '\nR stdout:\n' + self.stdout
         return s
     
     if PY3:
         __str__ = __unicode__
     else:
         def __str__(self):
             return unicode_to_str(unicode(self), 'utf-8')
 
 def Rconverter(Robj, dataframe=False):
     """
     Convert an object in R's namespace to one suitable
     for ipython's namespace.
 
     For a data.frame, it tries to return a structured array.
     It first checks for colnames, then names.
     If all are NULL, it returns np.asarray(Robj), else
     it tries to construct a recarray
 
     Parameters
     ----------
 
     Robj: an R object returned from rpy2
     """
     is_data_frame = ro.r('is.data.frame')
     colnames = ro.r('colnames')
     rownames = ro.r('rownames') # with pandas, these could be used for the index
     names = ro.r('names')
 
     if dataframe:
         as_data_frame = ro.r('as.data.frame')
         cols = colnames(Robj)
         _names = names(Robj)
         if cols != ri.NULL:
             Robj = as_data_frame(Robj)
             names = tuple(np.array(cols))
         elif _names != ri.NULL:
             names = tuple(np.array(_names))
         else: # failed to find names
             return np.asarray(Robj)
         Robj = np.rec.fromarrays(Robj, names = names)
     return np.asarray(Robj)
 
 @generic
 def pyconverter(pyobj):
     """Convert Python objects to R objects. Add types using the decorator:
     
     @pyconverter.when_type
     """
     return pyobj
 
 # The default conversion for lists seems to make them a nested list. That has
 # some advantages, but is rarely convenient, so for interactive use, we convert
 # lists to a numpy array, which becomes an R vector.
 @pyconverter.when_type(list)
 def pyconverter_list(pyobj):
     return np.asarray(pyobj)
 
 if pandas2ri is None:
     # pandas2ri was new in rpy2 2.3.3, so for now we'll fallback to pandas'
     # conversion function.
     try:
         from pandas import DataFrame
         from pandas.rpy.common import convert_to_r_dataframe
         @pyconverter.when_type(DataFrame)
         def pyconverter_dataframe(pyobj):
             return convert_to_r_dataframe(pyobj, strings_as_factors=True)
     except ImportError:
         pass
 
 @magics_class
 class RMagics(Magics):
     """A set of magics useful for interactive work with R via rpy2.
     """
 
     def __init__(self, shell, Rconverter=Rconverter,
                  pyconverter=pyconverter,
                  cache_display_data=False):
         """
         Parameters
         ----------
 
         shell : IPython shell
         
         Rconverter : callable
             To be called on values taken from R before putting them in the
             IPython namespace.
 
         pyconverter : callable
             To be called on values in ipython namespace before 
             assigning to variables in rpy2.
 
         cache_display_data : bool
             If True, the published results of the final call to R are 
             cached in the variable 'display_cache'.
 
         """
         super(RMagics, self).__init__(shell)
         self.cache_display_data = cache_display_data
 
         self.r = ro.R()
 
         self.Rstdout_cache = []
         self.pyconverter = pyconverter
         self.Rconverter = Rconverter
 
     def eval(self, line, line_mode):
         '''
         Parse and evaluate a line with rpy2.
         Returns the output to R's stdout() connection, and 
         the value generated by evaluating the code (see below)
         
-        In line mode (ie called with %R <stuff>), behavior
-        is unchanged, returns a python object representing
-        the final value, suitable for assignment into a 
-        python variable.
+        In line mode (ie called with %R <stuff>), resulting
+        values are not printed (explicit calls to the 
+        show/print R functions still result in properly
+        captured R output).
 
         In cell mode (called with %%R ...), behavior
-        now reproduces the REPL behavior of the R
+        reproduces the REPL behavior of the R
         interpreter (which agrees with how cells of
         python code are handled by the notebook).
 
         In cell mode if the last line of code is not
         an assignment, wrapped in invisible(), or 
         a call to a function which returns its value
         invisibly, the value will be printed using the
         show R function.
 
-        Actual evaluation of R code is done via a call
-        of the form withVisible({<code>})
+        Actual evaluation of R code is done via an R
+        call of the form withVisible({<code>})
         
         '''
         old_writeconsole = ri.get_writeconsole()
         ri.set_writeconsole(self.write_console)
         try:
             res = ro.r("withVisible({%s})" % line)
             value = res[0] #value
         except (ri.RRuntimeError, ValueError) as exception:
             warning_or_other_msg = self.flush() # otherwise next return seems to have copy of error
             raise RInterpreterError(line, str_to_unicode(str(exception)), warning_or_other_msg)
         if not line_mode and ro.conversion.ri2py(res[1])[0]:
             ro.r.show(value)
         text_output = self.flush()
         ri.set_writeconsole(old_writeconsole)
         return text_output, value
 
     def write_console(self, output):
         '''
         A hook to capture R's stdout in a cache.
         '''
         self.Rstdout_cache.append(output)
 
     def flush(self):
         '''
         Flush R's stdout cache to a string, returning the string.
         '''
         value = ''.join([str_to_unicode(s, 'utf-8') for s in self.Rstdout_cache])
         self.Rstdout_cache = []
         return value
 
     @skip_doctest
     @needs_local_scope
     @line_magic
     def Rpush(self, line, local_ns=None):
         '''
         A line-level magic for R that pushes
         variables from python to rpy2. The line should be made up
         of whitespace separated variable names in the IPython
         namespace::
 
             In [7]: import numpy as np
 
             In [8]: X = np.array([4.5,6.3,7.9])
 
             In [9]: X.mean()
             Out[9]: 6.2333333333333343
 
             In [10]: %Rpush X
 
             In [11]: %R mean(X)
             Out[11]: array([ 6.23333333])
 
         '''
         if local_ns is None:
             local_ns = {}
 
         inputs = line.split(' ')
         for input in inputs:
             try:
                 val = local_ns[input]
             except KeyError:
                 try:
                     val = self.shell.user_ns[input]
                 except KeyError:
                     # reraise the KeyError as a NameError so that it looks like
                     # the standard python behavior when you use an unnamed
                     # variable
                     raise NameError("name '%s' is not defined" % input)
 
             self.r.assign(input, self.pyconverter(val))
 
     @skip_doctest
     @magic_arguments()
     @argument(
         '-d', '--as_dataframe', action='store_true',
         default=False,
         help='Convert objects to data.frames before returning to ipython.'
         )
     @argument(
         'outputs',
         nargs='*',
         )
     @line_magic
     def Rpull(self, line):
         '''
         A line-level magic for R that pulls
         variables from python to rpy2::
 
             In [18]: _ = %R x = c(3,4,6.7); y = c(4,6,7); z = c('a',3,4)
 
             In [19]: %Rpull x  y z
 
             In [20]: x
             Out[20]: array([ 3. ,  4. ,  6.7])
 
             In [21]: y
             Out[21]: array([ 4.,  6.,  7.])
 
             In [22]: z
             Out[22]:
             array(['a', '3', '4'],
                   dtype='|S1')
 
 
         If --as_dataframe, then each object is returned as a structured array
         after first passed through "as.data.frame" in R before
         being calling self.Rconverter. 
         This is useful when a structured array is desired as output, or
         when the object in R has mixed data types. 
         See the %%R docstring for more examples.
 
         Notes
         -----
 
         Beware that R names can have '.' so this is not fool proof.
         To avoid this, don't name your R objects with '.'s...
 
         '''
         args = parse_argstring(self.Rpull, line)
         outputs = args.outputs
         for output in outputs:
             self.shell.push({output:self.Rconverter(self.r(output),dataframe=args.as_dataframe)})
 
     @skip_doctest
     @magic_arguments()
     @argument(
         '-d', '--as_dataframe', action='store_true',
         default=False,
         help='Convert objects to data.frames before returning to ipython.'
         )
     @argument(
         'output',
         nargs=1,
         type=str,
         )
     @line_magic
     def Rget(self, line):
         '''
         Return an object from rpy2, possibly as a structured array (if possible).
         Similar to Rpull except only one argument is accepted and the value is 
         returned rather than pushed to self.shell.user_ns::
 
             In [3]: dtype=[('x', '<i4'), ('y', '<f8'), ('z', '|S1')]
 
             In [4]: datapy = np.array([(1, 2.9, 'a'), (2, 3.5, 'b'), (3, 2.1, 'c'), (4, 5, 'e')], dtype=dtype)
 
             In [5]: %R -i datapy
 
             In [6]: %Rget datapy
             Out[6]: 
             array([['1', '2', '3', '4'],
                    ['2', '3', '2', '5'],
                    ['a', 'b', 'c', 'e']], 
                   dtype='|S1')
 
             In [7]: %Rget -d datapy
             Out[7]: 
             array([(1, 2.9, 'a'), (2, 3.5, 'b'), (3, 2.1, 'c'), (4, 5.0, 'e')], 
                   dtype=[('x', '<i4'), ('y', '<f8'), ('z', '|S1')])
 
         '''
         args = parse_argstring(self.Rget, line)
         output = args.output
         return self.Rconverter(self.r(output[0]),dataframe=args.as_dataframe)
 
 
     @skip_doctest
     @magic_arguments()
     @argument(
         '-i', '--input', action='append',
         help='Names of input variable from shell.user_ns to be assigned to R variables of the same names after calling self.pyconverter. Multiple names can be passed separated only by commas with no whitespace.'
         )
     @argument(
         '-o', '--output', action='append',
         help='Names of variables to be pushed from rpy2 to shell.user_ns after executing cell body and applying self.Rconverter. Multiple names can be passed separated only by commas with no whitespace.'
         )
     @argument(
         '-w', '--width', type=int,
         help='Width of png plotting device sent as an argument to *png* in R.'
         )
     @argument(
         '-h', '--height', type=int,
         help='Height of png plotting device sent as an argument to *png* in R.'
         )
 
     @argument(
         '-d', '--dataframe', action='append',
         help='Convert these objects to data.frames and return as structured arrays.'
         )
     @argument(
         '-u', '--units', type=unicode, choices=["px", "in", "cm", "mm"],
         help='Units of png plotting device sent as an argument to *png* in R. One of ["px", "in", "cm", "mm"].'
         )
     @argument(
         '-r', '--res', type=int,
         help='Resolution of png plotting device sent as an argument to *png* in R. Defaults to 72 if *units* is one of ["in", "cm", "mm"].'
         )
     @argument(
         '-p', '--pointsize', type=int,
         help='Pointsize of png plotting device sent as an argument to *png* in R.'
         )
     @argument(
         '-b', '--bg',
         help='Background of png plotting device sent as an argument to *png* in R.'
         )
     @argument(
         '-n', '--noreturn',
         help='Force the magic to not return anything.',
         action='store_true',
         default=False
         )
     @argument(
         'code',
         nargs='*',
         )
     @needs_local_scope
     @line_cell_magic
     def R(self, line, cell=None, local_ns=None):
         '''
         Execute code in R, and pull some of the results back into the Python namespace.
 
         In line mode, this will evaluate an expression and convert the returned value to a Python object.
         The return value is determined by rpy2's behaviour of returning the result of evaluating the
         final line. 
 
         Multiple R lines can be executed by joining them with semicolons::
 
             In [9]: %R X=c(1,4,5,7); sd(X); mean(X)
             Out[9]: array([ 4.25])
 
-        As a cell, this will run a block of R code, without bringing anything back by default::
+        As a cell, this will run a block of R code. By default the resulting value
+        is printed if it would be when evaluating the same code within an R REPL.
+        Nothing is returned to python by default.
 
             In [10]: %%R
                ....: Y = c(2,4,3,9)
-               ....: print(summary(lm(Y~X)))
-               ....:
+               ....: summary(lm(Y~X))
 
             Call:
             lm(formula = Y ~ X)
 
             Residuals:
                 1     2     3     4
              0.88 -0.24 -2.28  1.64
 
             Coefficients:
                         Estimate Std. Error t value Pr(>|t|)
             (Intercept)   0.0800     2.3000   0.035    0.975
             X             1.0400     0.4822   2.157    0.164
 
             Residual standard error: 2.088 on 2 degrees of freedom
             Multiple R-squared: 0.6993,Adjusted R-squared: 0.549
             F-statistic: 4.651 on 1 and 2 DF,  p-value: 0.1638
 
         In the notebook, plots are published as the output of the cell.
 
         %R plot(X, Y)
 
         will create a scatter plot of X bs Y.
 
         If cell is not None and line has some R code, it is prepended to
         the R code in cell.
 
         Objects can be passed back and forth between rpy2 and python via the -i -o flags in line::
 
             In [14]: Z = np.array([1,4,5,10])
 
             In [15]: %R -i Z mean(Z)
             Out[15]: array([ 5.])
 
 
             In [16]: %R -o W W=Z*mean(Z)
             Out[16]: array([  5.,  20.,  25.,  50.])
 
             In [17]: W
             Out[17]: array([  5.,  20.,  25.,  50.])
 
         The return value is determined by these rules:
 
         * If the cell is not None, the magic returns None.
 
         * If the cell evaluates as False, the resulting value is returned
         unless the final line prints something to the console, in
         which case None is returned.
 
         * If the final line results in a NULL value when evaluated
         by rpy2, then None is returned.
 
         * No attempt is made to convert the final value to a structured array.
         Use the --dataframe flag or %Rget to push / return a structured array.
 
         * If the -n flag is present, there is no return value.
 
         * A trailing ';' will also result in no return value as the last
         value in the line is an empty string.
 
         The --dataframe argument will attempt to return structured arrays. 
         This is useful for dataframes with
         mixed data types. Note also that for a data.frame, 
         if it is returned as an ndarray, it is transposed::
 
             In [18]: dtype=[('x', '<i4'), ('y', '<f8'), ('z', '|S1')]
 
             In [19]: datapy = np.array([(1, 2.9, 'a'), (2, 3.5, 'b'), (3, 2.1, 'c'), (4, 5, 'e')], dtype=dtype)
 
             In [20]: %%R -o datar
             datar = datapy
                ....: 
 
             In [21]: datar
             Out[21]: 
             array([['1', '2', '3', '4'],
                    ['2', '3', '2', '5'],
                    ['a', 'b', 'c', 'e']], 
                   dtype='|S1')
 
             In [22]: %%R -d datar
             datar = datapy
                ....: 
 
             In [23]: datar
             Out[23]: 
             array([(1, 2.9, 'a'), (2, 3.5, 'b'), (3, 2.1, 'c'), (4, 5.0, 'e')], 
                   dtype=[('x', '<i4'), ('y', '<f8'), ('z', '|S1')])
 
         The --dataframe argument first tries colnames, then names.
         If both are NULL, it returns an ndarray (i.e. unstructured)::
 
             In [1]: %R mydata=c(4,6,8.3); NULL
 
             In [2]: %R -d mydata
 
             In [3]: mydata
             Out[3]: array([ 4. ,  6. ,  8.3])
 
             In [4]: %R names(mydata) = c('a','b','c'); NULL
 
             In [5]: %R -d mydata
 
             In [6]: mydata
             Out[6]: 
             array((4.0, 6.0, 8.3), 
                   dtype=[('a', '<f8'), ('b', '<f8'), ('c', '<f8')])
 
             In [7]: %R -o mydata
 
             In [8]: mydata
             Out[8]: array([ 4. ,  6. ,  8.3])
 
         '''
 
         args = parse_argstring(self.R, line)
 
         # arguments 'code' in line are prepended to
         # the cell lines
 
         if cell is None:
             code = ''
             return_output = True
             line_mode = True
         else:
             code = cell
             return_output = False
             line_mode = False
 
         code = ' '.join(args.code) + code
 
         # if there is no local namespace then default to an empty dict
         if local_ns is None:
             local_ns = {}
 
         if args.input:
             for input in ','.join(args.input).split(','):
                 try:
                     val = local_ns[input]
                 except KeyError:
                     try:
                         val = self.shell.user_ns[input]
                     except KeyError:
                         raise NameError("name '%s' is not defined" % input)
                 self.r.assign(input, self.pyconverter(val))
 
         if getattr(args, 'units') is not None:
             if args.units != "px" and getattr(args, 'res') is None:
                 args.res = 72
             args.units = '"%s"' % args.units
 
         png_argdict = dict([(n, getattr(args, n)) for n in ['units', 'res', 'height', 'width', 'bg', 'pointsize']])
         png_args = ','.join(['%s=%s' % (o,v) for o, v in png_argdict.items() if v is not None])
         # execute the R code in a temporary directory
 
         tmpd = tempfile.mkdtemp()
         self.r('png("%s/Rplots%%03d.png",%s)' % (tmpd.replace('\\', '/'), png_args))
 
         text_output = ''
         try:
             if line_mode:
                 for line in code.split(';'):
                     text_result, result = self.eval(line, line_mode)
                     text_output += text_result
                 if text_result:
                     # the last line printed something to the console so we won't return it
                     return_output = False
             else:
                 text_result, result = self.eval(code, line_mode)
                 text_output += text_result
         
         except RInterpreterError as e:
             print(e.stdout)
             if not e.stdout.endswith(e.err):
                 print(e.err)
             rmtree(tmpd)
             return
 
         self.r('dev.off()')
 
         # read out all the saved .png files
 
         images = [open(imgfile, 'rb').read() for imgfile in glob("%s/Rplots*png" % tmpd)]
 
         # now publish the images
         # mimicking IPython/zmq/pylab/backend_inline.py
         fmt = 'png'
         mimetypes = { 'png' : 'image/png', 'svg' : 'image/svg+xml' }
         mime = mimetypes[fmt]
 
         # publish the printed R objects, if any
 
         display_data = []
         if text_output:
             display_data.append(('RMagic.R', {'text/plain':text_output}))
 
         # flush text streams before sending figures, helps a little with output
         for image in images:
             # synchronization in the console (though it's a bandaid, not a real sln)
             sys.stdout.flush(); sys.stderr.flush()
             display_data.append(('RMagic.R', {mime: image}))
 
         # kill the temporary directory
         rmtree(tmpd)
 
         # try to turn every output into a numpy array
         # this means that output are assumed to be castable
         # as numpy arrays
 
         if args.output:
             for output in ','.join(args.output).split(','):
                 self.shell.push({output:self.Rconverter(self.r(output), dataframe=False)})
 
         if args.dataframe:
             for output in ','.join(args.dataframe).split(','):
                 self.shell.push({output:self.Rconverter(self.r(output), dataframe=True)})
 
         for tag, disp_d in display_data:
             publish_display_data(tag, disp_d)
 
         # this will keep a reference to the display_data
         # which might be useful to other objects who happen to use
         # this method
 
         if self.cache_display_data:
             self.display_cache = display_data
 
         # if in line mode and return_output, return the result as an ndarray
         if return_output and not args.noreturn:
             if result != ri.NULL:
                 return self.Rconverter(result, dataframe=False)
 
 __doc__ = __doc__.format(
                 R_DOC = ' '*8 + RMagics.R.__doc__,
                 RPUSH_DOC = ' '*8 + RMagics.Rpush.__doc__,
                 RPULL_DOC = ' '*8 + RMagics.Rpull.__doc__,
                 RGET_DOC = ' '*8 + RMagics.Rget.__doc__
 )
 
 
 def load_ipython_extension(ip):
     """Load the extension in IPython."""
     ip.register_magics(RMagics)
     # Initialising rpy2 interferes with readline. Since, at this point, we've
     # probably just loaded rpy2, we reset the delimiters. See issue gh-2759.
     if ip.has_readline:
         ip.readline.set_completer_delims(ip.readline_delims)