Package memoize (python-based extraction) Error: Python module 'pdfrw' was not found

I don't own a MAC so I'm afraid I cannot offer a definitive solution (even if I'm the author of Memoize), but I believe the problem might be multiple Python installations, as hinted in the comments to the question. In other words, it might be that package pdfrw2 is not installed the same Python that TeX is accessing.

I can only offer an idea for a very hacky way of installing the package in the correct Python: from TeX, with shell escape. This should guarantee that the package is installed in the Python accessed by TeX, but beware that you should follow this suggestion at your own risk.

Put the following into a file, say install-pdfrw2.tex:

\immediate\write18{%
  python -m pip install pdfrw2
}
\bye

and execute (from the command-line):

pdftex -shell-escape install-pdfrw2

I believe that installed in this way, the library should be available under all TeX engines, including LuaTeX used by the OP. If not, replacing pdftex in this command line by luatex should do the trick.

As also mentioned in the comments, the package which needs to be installed is named pdfrw2 on PyPI, but this package provides module pdfrw. I agree this is somewhat confusing. I'm guessing the situation arose because package pdfrw2 is a fork of package pdfrw, and the module name wasn't changed for compatibility.

UPDATE (Jan 12)

Let's gather some further information. Please create file sysinfo.py with the following contents:

import sys
print("__file__:", __file__)
for attr in ('argv', 'executable', 'version', 'prefix', 'exec_prefix', 'base_prefix', 'base_exec_prefix', 'path'):
    print(f"sys.{attr}:", getattr(sys, attr))

Execute this from within TeX: create the sysinfo.tex and execute it via pdftex -shell-escape syinfo.

\immediate\write18{%
  python sysinfo.py
}
\bye

Ideally, if the system allows you to do so, you could put the contents of sysinfo.py into memoize-extract.py (at the top, just after imports) and see what's printed out then. (And if the information we gather turns out to be useful, I'll include this debug code in the script in the next release.)

As of Jan 13, 2025:

I am posting here an AI summary of what I, cfr, Sašo Živanović and the AI have worked on for some time. I’ve had no prior experience working with Python, so this issue was a challenge. Someone, somewhere, sometime may be able to use what happened here and move forward.

Here’s a summary of the steps we took to resolve the Python module 'pdfrw' was not found. issue that arose from the multiple Python versions issue on my Mac:

Summary of Steps to Manage Python Versions on macOS

1. Identified Installed Python Versions:

• Used the command python3 -m site to check the installed Python versions and their locations.
• Found that Python 3.9.6 was installed in /usr/bin, which is the system-installed version.

2. Checked for Other Python Installations:

• Used ls /usr/local/bin | grep python to identify additional Python versions (3.13 and 3.14) installed in /usr/local/bin.

3. Removed Unwanted Python Versions:

• Executed commands to remove the unnecessary Python versions from /usr/local/bin to clean up the environment.

4. Verified Current Python Version:

• Confirmed that the system Python version (3.9.6) was still accessible by running python3 -V.

5. Addressed PATH Issues:

• Noticed a warning about pip scripts not being in the PATH.
• Edited the shell configuration file (e.g., ~/.zshrc) to add export PATH="$PATH:/Users/koolstofgenesis/Library/Python/3.9/bin” to add /Users/<user_name>/Library/Python/3.9/bin to the directory PATH.

6. Applied Changes and Verified:

• Sourced the configuration file (source ~/.zshrc) to apply the changes and verified (echo $PATH) that the PATH was updated correctly.
• Updated the pip command using /Library/Developer/CommandLineTools/usr/bin/python3 -m pip install --upgrade pip.
• Tested the pip command to ensure it was working properly.

7. Reinstalled the Python pdfrw2 module using pip3 unto the Python system-installed version 3.9.6:

• pip3 install pdfrw2.

8. Retested the memoize LaTeX code that utilizes the memoize Python pdfrw module. Now it Works!

\documentclass[12pt,letterpaper]{article}

\usepackage[extract=python]{memoize}

\usepackage{tikz}
\usepackage{forest}

\title{memoize}

\begin{document}

Memoize will automatically externalize\\

\begin{tikzpicture}
    \node(node)
    [align=center,ellipse,draw]
    {TikZ\\pictures};
\end{tikzpicture}

\vspace{-2.0cm}     % \vspace added to adjust the vertical location of the 'forest'
\hspace{2.5cm}      % \hspace added to adjust the horizontal location of the 'forest'
\begin{forest}
    [and Forest trees [and]
    [Forest trees[Forest][trees]]]
\end{forest}
    
\end{document}

Key Takeaways

• Managing Python Versions: It's important to keep track of installed Python versions and clean up any unnecessary installations to avoid conflicts.
• Setting Up the Environment: Properly configuring the PATH is crucial for accessing installed scripts and tools easily.
• Using Built-in Tools: Utilizing built-in commands and shell configuration files can help manage the development environment effectively.

What I found was that brew had re-installed Python on my Mac which somehow interfered with Python finding the pdfrw module when I tried running my LaTeX memoize package, thus returning me to the pdfrw module not found error I had worked so hard to eliminate.

Unable to properly install the path to the Python pdfrw module so that the pdfrw module could be located by the LaTeX memoize package, I was left with the only remaining alternative but to un-install ALL Python versions on my Sequoia Mac, except for the Python system version.

To un-install all brew’ed Python versions, I employed the 2nd answer instructions to: Uninstalling python3 on MacOs, at https://stackoverflow.com/questions/60280377/uninstalling-python3-on-macos by running brew uninstall [email protected] to remove the brew’ed Python version 3.13 et al. from my Mac.

Then, I followed the instructions outlined in the 2nd answer to: How can I safely uninstall one version of python without removing others? at https://stackoverflow.com/questions/44231329/how-can-i-safely-uninstall-one-version-of-python-without-removing-others to un-install any non-brew'ed Python versions (without touching the system version of Python) that were left after I had un-installed all the brew’ed versions of Python.

I then attempted to re-install the Python pdfrw module that was needed by the LaTeX memoize package.

With just the Python system version installed, when I attempted to re-install the pdfrw module, I received a message “Error: Current platform "darwin 24" does not match expected platform "darwin 23”. So I followed the MacPorts instructions to update my Sequoia system (Install MacPorts for your version of the Mac operating system:) at: https://www.macports.org/install.php. The MacPorts installation went smoothly.

Lastly, to re-install the Python pdfrw module, I followed the instructions sudo port install py27-pdfrw to install the py27-pdfrw Python module (at: https://ports.macports.org/port/py27-pdfrw/).

It all worked! I was able to run the MWE test.tex LaTeX code (on Page 9 in Section 2.1 of the Memoize documentation by Sašo Živanovic, the package author) without encountering the dreaded pdfrw module not found error.

Now I just need to stop brew from re-installing those Python packages.