Source code for sympy.printing.preview

from __future__ import with_statement

import os
import time
import tempfile

from latex import latex

[docs]def preview(expr, output='png', viewer=None, euler=True, packages=(), **latex_settings): r""" View expression or LaTeX markup in PNG, DVI, PostScript or PDF form. If the expr argument is an expression, it will be exported to LaTeX and then compiled using available the TeX distribution. The first argument, 'expr', may also be a LaTeX string. The function will then run the appropriate viewer for the given output format or use the user defined one. By default png output is generated. By default pretty Euler fonts are used for typesetting (they were used to typeset the well known "Concrete Mathematics" book). For that to work, you need the 'eulervm.sty' LaTeX style (in Debian/Ubuntu, install the texlive-fonts-extra package). If you prefer default AMS fonts or your system lacks 'eulervm' LaTeX package then unset the 'euler' keyword argument. To use viewer auto-detection, lets say for 'png' output, issue >>> from sympy import symbols, preview, Symbol >>> x, y = symbols("x,y") >>> preview(x + y, output='png') # doctest: +SKIP This will choose 'pyglet' by default. To select a different one, do >>> preview(x + y, output='png', viewer='gimp') # doctest: +SKIP The 'png' format is considered special. For all other formats the rules are slightly different. As an example we will take 'dvi' output format. If you would run >>> preview(x + y, output='dvi') # doctest: +SKIP then 'view' will look for available 'dvi' viewers on your system (predefined in the function, so it will try evince, first, then kdvi and xdvi). If nothing is found you will need to set the viewer explicitly. >>> preview(x + y, output='dvi', viewer='superior-dvi-viewer') # doctest: +SKIP This will skip auto-detection and will run user specified 'superior-dvi-viewer'. If 'view' fails to find it on your system it will gracefully raise an exception. You may also enter 'file' for the viewer argument. Doing so will cause this function to return a file object in read-only mode. Currently this depends on pexpect, which is not available for windows. Additional keyword args will be passed to the latex call, e.g., the symbol_names flag. >>> phidd = Symbol('phidd') >>> preview(phidd, symbol_names={phidd:r'\ddot{\varphi}'}) # doctest: +SKIP """ # we don't want to depend on anything not in the # standard library with SymPy by default import pexpect special = [ 'pyglet' ] if viewer is None: if output == "png": viewer = "pyglet" else: # sorted in order from most pretty to most ugly # very discussable, but indeed 'gv' looks awful :) candidates = { "dvi" : [ "evince", "okular", "kdvi", "xdvi" ], "ps" : [ "evince", "okular", "gsview", "gv" ], "pdf" : [ "evince", "okular", "kpdf", "acroread", "xpdf", "gv" ], } try: for candidate in candidates[output]: if pexpect.which(candidate): viewer = candidate break else: raise SystemError("No viewers found for '%s' output format." % output) except KeyError: raise SystemError("Invalid output format: %s" % output) else: if viewer not in special and not pexpect.which(viewer): raise SystemError("Unrecognized viewer: %s" % viewer) actual_packages = packages + ("amsmath", "amsfonts") if euler: actual_packages += ("euler",) package_includes = "\n".join(["\\usepackage{%s}" % p for p in actual_packages]) format = r"""\documentclass[12pt]{article} %s \begin{document} \pagestyle{empty} %s \vfill \end{document} """ % (package_includes, "%s") if isinstance(expr, str): latex_string = expr else: latex_string = latex(expr, mode='inline', **latex_settings) tmp = tempfile.mktemp() with open(tmp + ".tex", "w") as tex: tex.write(format % latex_string) cwd = os.getcwd() os.chdir(tempfile.gettempdir()) if os.system("latex -halt-on-error %s.tex" % tmp) != 0: raise SystemError("Failed to generate DVI output.") os.remove(tmp + ".tex") os.remove(tmp + ".aux") os.remove(tmp + ".log") if output != "dvi": command = { "ps" : "dvips -o %s.dvi", "pdf" : "dvipdf %s.dvi %s.pdf", "png" : "dvipng -T tight -z 9 " + \ "--truecolor -o %s.png %s.dvi", } try: if os.system(command[output] % (tmp, tmp)) != 0: raise SystemError("Failed to generate '%s' output." % output) else: os.remove(tmp + ".dvi") except KeyError: raise SystemError("Invalid output format: %s" % output) src = "%s.%s" % (tmp, output) src_file = None if viewer == "file": src_file = open(src, 'rb') elif viewer == "pyglet": try: from pyglet import window, image, gl from pyglet.window import key except ImportError: raise ImportError("pyglet is required for plotting.\n visit") if output == "png": from pyglet.image.codecs.png import PNGImageDecoder img = image.load(src, decoder=PNGImageDecoder()) else: raise SystemError("pyglet preview works only for 'png' files.") offset = 25 win = window.Window( width = img.width + 2*offset, height = img.height + 2*offset, caption = "sympy", resizable = False ) win.set_vsync(False) try: def on_close(): win.has_exit = True win.on_close = on_close def on_key_press(symbol, modifiers): if symbol in [key.Q, key.ESCAPE]: on_close() win.on_key_press = on_key_press def on_expose(): gl.glClearColor(1.0, 1.0, 1.0, 1.0) gl.glClear(gl.GL_COLOR_BUFFER_BIT) img.blit( (win.width - img.width) / 2, (win.height - img.height) / 2 ) win.on_expose = on_expose while not win.has_exit: win.dispatch_events() win.flip() except KeyboardInterrupt: pass win.close() else: os.system("%s %s &> /dev/null &" % (viewer, src)) time.sleep(2) # wait for the viewer to read data os.remove(src) os.chdir(cwd) if src_file is not None: return src_file