Python: Handle digits followed by letters in variable names when using sympy.parsing.mathematica

I am using the tool sympy.parsing.mathematica to parse Mathematica expressions into python syntax. I would like to be able to handle variable names that contain digits followed by letters.

For example, when parsing the string "1 + a23b + 4" by calling mathematica("1 + a23b") I get the output "a23*b + 1". How can I indicate that I want "a23b" to be treated as a single variable, so that the output in the above example becomes "a23b + 1" instead?

I tried passing a dictionary of the form {'a23b':'a23b'} by calling mathematica("1 + a23b",{'a23b':'a23b'}). However, this raises a ValueError with the following message ValueError: 'a23b' function form is invalid..

Any ideas how to solve this?

Answer

In SymPy 1.11 the mathematica parsing function is deprecated:

In [3]: from sympy.parsing.mathematica import mathematica

In [4]: mathematica("1 + a23b")
<ipython-input-4-925ed25e63e8>:1: SymPyDeprecationWarning: 

The ``mathematica`` function for the Mathematica parser is now
deprecated. Use ``parse_mathematica`` instead.
The parameter ``additional_translation`` can be replaced by SymPy's
.replace( ) or .subs( ) methods on the output expression instead.

See https://docs.sympy.org/latest/explanation/active-deprecations.html#mathematica-parser-new
for details.

This has been deprecated since SymPy version 1.11. It
will be removed in a future version of SymPy.

  mathematica("1 + a23b")
Out[4]: a₂₃⋅b + 1

Instead it is recommended to use the parse_mathematica function which handles this case in the way that you want it to:

In [5]: from sympy.parsing.mathematica import parse_mathematica

In [6]: parse_mathematica("1 + a23b")
Out[6]: a23b + 1