Transferring an equation from Python sympy to a LibreOffice formula

jpsa · January 9, 2025, 12:39pm

I’ve been trying to find the best way of transferring an equation from the Python sympy library into a LibreOffice formula object. I couldn’t find much on the Internet for this, so I’m documenting the results of my experiments here, in case it’s of any use to anyone, and in case anyone can suggest a better way of going about things!

The best I’ve come up with is…

import sympy.printing
import tkinter


def sp2lo(eqn, filename=None):
    mml = sympy.printing.mathml(eqn, printer='presentation')
    mml = mml.replace('<mo>&InvisibleTimes;</mo>', '')      # See notes below!
    mml = ''.join(['<math xmlns="http://www.w3.org/1998/Math/MathML">', mml,  '</math>'])

    if filename is None:
        tk = tkinter.Tk()
        txt = tkinter.Text(tk)
        txt.pack()
        txt.insert(tkinter.END, mml)
        tk.mainloop()
    else:
        with open(filename, 'w') as file:
            file.write(mml)

which, depending on the second argument, either writes MathML to a file or displays it in a text box from which it can be copied and pasted. Having done that, give the command

Insert>OLE Object>Formula Object

and then, in the formula editor, either of

Tools>Import Formula…
Tools>Import MathML from Clipboard

Alternatively, and perhaps best of all, rather than using “Insert>OLE Object>Formula Object”, give the command

Insert>OLE Object>OLE Object…

choose “Create from file” and perhaps “Link to file” as well, then navigate to a file with suffix “.mml”.

There are a few interesting/confusing features which puzzled me along the way…

LibreOffice seems only to accept ‘presentation’ style MathML. If you give it ‘content’ style MathML (sympy’s default) it fails silently.
sympy’s mathml converter doesn’t add the surrounding <math>…</math> elements, and LibreOffice fails silently if these are missing.
If there are <mo>⁢</mo> elements in the MathML, LibreOffice Import fails silently (though, curiously, giving LibreOffice Math’s File>Open… command is happy to accept an MML file which contains such elements, as is “Insert>OLE Object>OLE Object…”).

This all tested with LibreOffice version 24.8.4.2 and sympy version 1.13.3