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@ahwillia ahwillia/equations.tex
Last active Jun 2, 2018

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Export a sequence of LaTeX equations to individual image files
% quad %
\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
% optimization %
\usepackage{amsmath}
\begin{equation*}
\begin{aligned}
& \underset{x}{\text{minimize}}
& & f_0(x) \\
& \text{subject to}
& & f_i(x) \leq b_i, \; i = 1, \ldots, m.
\end{aligned}
\end{equation*}
#!/usr/bin/python
import re
import sys
import tempfile
import subprocess
import os
def export_equations(filename,dest='./',dpi=300):
with open(filename,'r') as f:
s = f.read()
names = [ dest+re.sub('[\W_]','',n) for n in re.findall('%.{,}%\n',s) ]
eqns = re.split('%.{,}%\n',s)[1:]
tmp_name = '.tempfile_latex_to_png'
for outfile,eq in zip(names,eqns):
# make temporary file
temp = open(tmp_name+'.tex','w')
packages,body = [],[]
for eqline in eq.split('\n'):
if eqline.startswith('\usepackage'):
packages.append(eqline)
else:
body.append(eqline)
# write equation
temp.write('\documentclass[preview]{standalone}\n')
[ temp.write(pkg+'\n') for pkg in packages ]
temp.write('\\begin{document}\n')
temp.write('\pagestyle{empty}\n')
[ temp.write(line+'\n') for line in body ]
temp.write('\end{document}\n')
# compile latex
temp.close()
subprocess.call(['pdflatex','-interaction=nonstopmode',tmp_name])
# crop pdf, convert to png
subprocess.call('pdfcrop %s.pdf %s.pdf'%(tmp_name,outfile),shell=True)
subprocess.call('convert -density %i %s.pdf %s.png'%(dpi,outfile,outfile),shell=True)
# delete all temporary files
subprocess.call(['rm', tmp_name+'.tex'])
subprocess.call(['rm', tmp_name+'.pdf'])
subprocess.call(['rm', tmp_name+'.log'])
subprocess.call(['rm', tmp_name+'.aux'])
if __name__=="__main__":
fn = 'main.tex' if len(sys.argv)<2 else sys.argv[1]
df = './' if len(sys.argv)<3 else sys.argv[2]
dpi = 300 if len(sys.argv)<4 else sys.argv[3]
export_equations(fn,df,dpi)
@ahwillia

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ahwillia commented Jul 19, 2016

Running $ ./scrap_latex.py from the command line should produce two files:

quad.pdf
quad

optimization.pdf
optimization

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