%% Copyright 2021-2024 Tobias Enderle
%%
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\documentclass{article}

\usepackage{pyluatex}
\usepackage{unicode-math}
\usepackage{pgf}
\usepackage{url}

\title{PyLuaTeX Example -- Matplotlib PGF}
\author{Tobias Enderle}

\begin{document}

\maketitle

In this document we demonstrate how \emph{matplotlib} plots can be generated and
included in a document. In the Python code in this document, the plot is
configured and saved to PGF\footnote{\url{https://ctan.org/pkg/pgf}} code.
The PGF code is then included in the document and creates the plot.

To avoid intermediate files, the PGF code is saved into an in-memory file
using the Python \verb|io.StringIO| class%
\footnote{\url{https://docs.python.org/3/library/io.html#io.StringIO}}.

\begin{center}
\begin{python}
# example based on
# https://matplotlib.org/stable/gallery/lines_bars_and_markers/simple_plot.html
import matplotlib.pyplot as plt
import numpy as np
import io

t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2 * np.pi * t)

fig, ax = plt.subplots(figsize=(5, 3.5))
ax.plot(t, s)

ax.set(xlabel='time (s)', ylabel='voltage (mV)',
       title='About as simple as it gets, folks')
ax.grid()

with io.StringIO() as file:  # save to "in-memory file"
    fig.savefig(file, format='pgf', bbox_inches='tight', pad_inches=0.1)
    print(file.getvalue())
\end{python}
\end{center}

For an alternative approach of creating plots with \emph{matplotlib},
consider the example \verb|matplotlib-external.tex|.

\end{document}