Exporting Tex Elements As Images Using Python.

22 January 2022 - less than 1 min read time
Tags: Tex Scripting Workflow

Today while writing a blog post on a quantum circuit trick, I needed to create some quantum circuit diagrams. First I thought of using Qiskit or Cirq for it, but the overhead to install and setup them didn’t seem worth it. So I tried Tikz, and a Tex package called Qcircuit.

I wanted to export the circuit created using Qcircuit as images, and it took a while to figure out an optimal way to do it. I decided to write it here since this method is very versatile and can be used to export tables, tikz images, and a lot more.

Note: Commands here are for Arch. You can use apt for debian distros.

You need to have tex installed in your system. Packages I use are

sudo pacman -S texlive-most texlive-core texlive-science texlive-latexextra texlive-bibtexextra texlive-publishers texlive-pictures

Some of these will be useless for you so check with documentation before installing to avoid polluting your system.

You need a python packages latextools and drawsvg.

pip install latextools drawsvg

You need pdf2svg to convert the generated pdf to svg, which can then be converted to png, etc.

yay -S pdf2svg

You need to install Qcircuit from CTAN. Create a path $HOME/texmf/tex/latex/qcircuit. Then download the .sty file into that location. You can figure out above path using kpsewhich -var-value TEXMFHOME

Now you can use latextools to export a latex snippet as an image. Here is a short snippet.

import latextools

pdf = latextools.render_qcircuit(r'''
         \push{\ket{a}} & \ctrl{1} & \targ & \ctrl{1} & \qw & \push{\ket{b}} \\
         \push{\ket{b}} & \targ & \ctrl{-1} & \targ & \qw & \push{\ket{a}} \\
        ''')

pdf.save('swap-using-cnot.pdf')
pdf.rasterize('swap-using-cnot.png', scale=3)

The latextools documentation lists more examples.