Best Open-Source Python Libraries for Excel


Pycel is a small python library that can translate an Excel spreadsheet into executable python code which can be run independently of Excel.

The python code is based on a graph and uses caching & lazy evaluation to ensure (relatively) fast execution. The graph can be exported and analyzed using tools like Gephi. See the contained example for an illustration.

The full motivation behind pycel including some examples & screenshots is described in this blog post

The good:

All the main mathematical functions (sin, cos, atan2, …) and operators (+,/,^, …) are supported as are ranges (A5:D7), and functions like MIN, MAX, INDEX, LOOKUP, and LINEST.

The codebase is small, relatively fast and should be easy to understand and extend.

I have tested it extensively on spreadsheets with 10 sheets & more than 10000 formulae. In that case calculation of the equations takes about 50ms and agrees with Excel up to 5 decimal places.

The bad:

My development is driven by the particular spreadsheets I need to handle so I have only added support for functions that I need. However, it is should be straightforward to add support for others.

The code does currently not support cell references so a function like OFFSET would take some more work to implement. Not inherently difficult, its just that I have had no need for references yet. Also, for obvious reasons, any VBA code is not compiled but needs to be re-implemented manually on the python side.

The Ugly:

The resulting graph-based code is fast enough for my purposes but to make it truly fast you would probably replace the graph with a dependency tracker based on sparse matrices or something similar.


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  • License: GPL-3.0
  • Author: Dirk Gorissen
  • Last update: N/A