IPython/extensions/sympyprinting.py

"""
A print function that pretty prints sympy Basic objects.

:moduleauthor: Brian Granger

Usage
=====

Once the extension is loaded, Sympy Basic objects are automatically
pretty-printed.

"""
#-----------------------------------------------------------------------------
#  Copyright (C) 2008  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.
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

from IPython.lib.latextools import latex_to_png
from IPython.testing import decorators as dec
# use @dec.skipif_not_sympy to skip tests requiring sympy

try:
    from sympy import pretty, latex
except ImportError:
    pass

#-----------------------------------------------------------------------------
# Definitions of special display functions for use with IPython
#-----------------------------------------------------------------------------

def print_basic_unicode(o, p, cycle):
    """A function to pretty print sympy Basic objects."""
    if cycle:
        return p.text('Basic(...)')
    out = pretty(o, use_unicode=True)
    if '\n' in out:
        p.text(u'\n')
    p.text(out)


def print_png(o):
    """
    A function to display sympy expression using inline style LaTeX in PNG.
    """
    s = latex(o, mode='inline')
    # mathtext does not understand certain latex flags, so we try to replace
    # them with suitable subs.
    s = s.replace('\\operatorname','')
    s = s.replace('\\overline', '\\bar')
    png = latex_to_png(s)
    return png


def print_display_png(o):
    """
    A function to display sympy expression using display style LaTeX in PNG.
    """
    s = latex(o, mode='plain')
    s = s.strip('$')
    # As matplotlib does not support display style, dvipng backend is
    # used here.
    png = latex_to_png('$$%s$$' % s, backend='dvipng')
    return png


def can_print_latex(o):
    """
    Return True if type o can be printed with LaTeX.

    If o is a container type, this is True if and only if every element of o
    can be printed with LaTeX.
    """
    import sympy
    if isinstance(o, (list, tuple, set, frozenset)):
        return all(can_print_latex(i) for i in o)
    elif isinstance(o, dict):
        return all((isinstance(i, basestring) or can_print_latex(i)) and can_print_latex(o[i]) for i in o)
    elif isinstance(o,(sympy.Basic, sympy.matrices.Matrix, int, long, float)):
        return True
    return False

def print_latex(o):
    """A function to generate the latex representation of sympy
    expressions."""
    if can_print_latex(o):
        s = latex(o, mode='plain')
        s = s.replace('\\dag','\\dagger')
        s = s.strip('$')
        return '$$%s$$' % s
    # Fallback to the string printer
    return None

_loaded = False

def load_ipython_extension(ip):
    """Load the extension in IPython."""
    import sympy
    global _loaded
    if not _loaded:
        plaintext_formatter = ip.display_formatter.formatters['text/plain']

        for cls in (object, str):
            plaintext_formatter.for_type(cls, print_basic_unicode)

        printable_containers = [list, tuple]

        # set and frozen set were broken with SymPy's latex() function, but
        # was fixed in the 0.7.1-git development version. See
        # http://code.google.com/p/sympy/issues/detail?id=3062.
        if sympy.__version__ > '0.7.1':
            printable_containers += [set, frozenset]
        else:
            plaintext_formatter.for_type(cls, print_basic_unicode)

        plaintext_formatter.for_type_by_name(
            'sympy.core.basic', 'Basic', print_basic_unicode
        )
        plaintext_formatter.for_type_by_name(
            'sympy.matrices.matrices', 'Matrix', print_basic_unicode
        )

        png_formatter = ip.display_formatter.formatters['image/png']

        png_formatter.for_type_by_name(
            'sympy.core.basic', 'Basic', print_png
        )
        png_formatter.for_type_by_name(
            'sympy.matrices.matrices', 'Matrix', print_display_png
        )
        for cls in [dict, int, long, float] + printable_containers:
            png_formatter.for_type(cls, print_png)

        latex_formatter = ip.display_formatter.formatters['text/latex']
        latex_formatter.for_type_by_name(
            'sympy.core.basic', 'Basic', print_latex
        )
        latex_formatter.for_type_by_name(
            'sympy.matrices.matrices', 'Matrix', print_latex
        )

        for cls in printable_containers:
            # Use LaTeX only if every element is printable by latex
            latex_formatter.for_type(cls, print_latex)

        _loaded = True