Scale .pgf image but preserve font size

Question

Using Matplotlib, I generated a .pgf image.

import matplotlib
matplotlib.rcParams.update({"pgf.texsystem": "pdflatex"})
from matplotlib.pyplot import subplots, show
from numpy import linspace
x = linspace(0, 100, 30)
fig, ax = subplots(figsize = (10, 6))
ax.scatter(x, x)
fig.tight_layout()
fig.savefig('figure.pgf')

Which generates a long file: http://pastebin.com/tjLtTi5Q . I include this image in the document by using

    \usepackage{pgf}
    \input{testfig.pgf}

I would like to scale it in such a way that the font size remains the same. Preferably by wrapping something around the \input{...} rather than changing the pgf file, though the later is acceptable if that's the only way.

Previous attempts include:

• \begin{pgfpicture}[scale=0.5] found here, but scale only exists for tikzpicture

• Trying to apply pgfmagnify, which I found here but can't get to work and can't find much documentation

  \begin{pgfmagnify}{2}{2}
      \begin{pgfpicture}
      ....
  \end{pgfmagnify} 
  

• Using \begin{pgfpicture}[width=0.5] which also doesn't do anything.

• Using resizebox as mentioned here:

  \resizebox{0.7\textwidth}{!}{\input{figure.pgf}}
  

which (perhaps obviously) does not preserve font size.

EDIT: picture using the suggestion in the comment by Harish Kumar:

Part of the file that seems related to fonts:

\pgftext[x=0.501680in,y=2.691389in,right,]{{\sffamily\fontsize{12.000000}{14.400000}\selectfont 40}}%

Answer 1

You can scale the graphics by k using for example scalebox and scale the font by 1/k to compensate this. If you compile with XeLaTeX or LuaLaTeX you can use the scale features of fontspec.

Here is a simple example :

% to compile with XeLaTeX or LuaLaTeX
\documentclass[varwidth,border=50]{standalone}
\usepackage{fontspec}
\usepackage{pgf}

\begin{document}

% font scale = .25*4 = 1
\setsansfont{Latin Modern Sans}[Scale=.25]%
\scalebox{4}{
  \begin{pgfpicture}
    \pgfsetstrokecolor{red}%
    \pgfpathrectangle{\pgfpointorigin}{\pgfqpoint{5mm}{5mm}}%
    \pgfusepath{draw}%
    \pgftext[x=4,y=4]{{\sffamily\fontsize{12.000000}{14.400000}\selectfont 40}}%
  \end{pgfpicture}
}

% font scale = .5*2 = 1
\setsansfont{Latin Modern Sans}[Scale=.5]%
\scalebox{2}{
  \begin{pgfpicture}
    \pgfsetstrokecolor{red}%
    \pgfpathrectangle{\pgfpointorigin}{\pgfqpoint{5mm}{5mm}}%
    \pgfusepath{draw}%
    \pgftext[x=4,y=4]{{\sffamily\fontsize{12.000000}{14.400000}\selectfont 40}}%
  \end{pgfpicture}
}

\end{document}

Answer 2

You have full control over the plot dimensions in the axis environment of tikzpicture.

\begin{tikzpicture}
\begin{axis}[
width=\textwidth,
height=\textwidth
]
...
\end{tikzpicture}

Here you can replace \textwidth with any valid latex dimension, and the font sizes match the document font no matter what you set width and height to.

This will require editing the pgf file, which you say you don't want to do, but I honestly think this is the easiest way.

I highly suggest you look into matplotlib2tikz, which generated a pgf file that is much easier to work with than the native matplotlib pgf backend.