Source code for sympy.printing.preview

import os
import time
import tempfile

from latex import latex

[docs]def preview(expr, output='png', viewer=None, euler=True): """View expression in PNG, DVI, PostScript or PDF form. This will generate LaTeX representation of the given expression and compile it using available TeX distribution. Then it will run 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 * >> x, y = symbols("x,y") >> preview(x + y, output='png') This will choose 'pyglet by default. To select different one:: >> preview(x + y, output='png', viewer='gimp') 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') 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') 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. Currently this depends on pexpect, which is not available for windows. """ # 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) if not euler: format = r"""\documentclass[12pt]{article} \usepackage{amsmath} \begin{document} \pagestyle{empty} %s \vfill \end{document} """ else: format = r"""\documentclass[12pt]{article} \usepackage{amsmath} \usepackage{eulervm} \begin{document} \pagestyle{empty} %s \vfill \end{document} """ tmp = tempfile.mktemp() tex = open(tmp + ".tex", "w") tex.write(format % latex(expr, mode='inline')) tex.close() 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.ps %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) if viewer == "pyglet": try: from pyglet import window, image, gl from pyglet.window import key except: raise ImportError("pyglet is required for plotting.\n visit http://www.pyglet.org/") 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)