Fix a bug in simplify_expr() reading symbols with illegal characters

[nikgup11]

Fixes #26184

Description:
Issue author alfadir opened an issue about how using imported parameter names in parse_expr from sympy.parsing.sympy_parser contains symbols with special characters. This causes confusion in the parser where those imported symbols get mismatched and don't correctly align with the result. For example, "pro-duct" should match with "product". They provided a tok.py test script that they wrote which includes their proposed fix of using a dictionary to map the symbols, which only solved half of the problem, as seen in simplify_expr_new(). My changes implemented in simplify_expr_new_v2() add to their solution by including calls to the RegEx library to filter out integers (0-9) and characters
(+, -, .) from the input symbol so that the dictionary maps to that.

Release Notes

• functions
  • Fixed a bug in simplify_expr(). Formerly, local_dict would map {'pro-duct' : 'pro-duct'} now it maps {'pro-duct' : 'product'}

[sympy-bot]

✅

Hi, I am the SymPy bot. I'm here to help you write a release notes entry. Please read the guide on how to write release notes.

Your release notes are in good order.

Here is what the release notes will look like:

• functions
  • Fixed a bug in simplify_expr(). Formerly, local_dict would map {'pro-duct' : 'pro-duct'} now it maps {'pro-duct' : 'product'} (#26531 by @nikgup11)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.13.

Click here to see the pull request description that was parsed.

Fixes #26184 

Description:
Issue author alfadir opened an issue about how using imported parameter names in parse_expr from sympy.parsing.sympy_parser contains symbols with special characters. This causes confusion in the parser where those imported symbols get mismatched and don't correctly align with the result. For example, "pro-duct" should match with "product". They provided a tok.py test script that they wrote which includes their proposed fix of using a dictionary to map the symbols, which only solved half of the problem, as seen in simplify_expr_new(). My changes implemented in simplify_expr_new_v2() add to their solution by including calls to the RegEx library to filter out integers (0-9) and characters 
(+, -, .) from the input symbol so that the dictionary maps to that. 

#### Release Notes

<!-- BEGIN RELEASE NOTES -->
* functions
  * Fixed a bug in simplify_expr(). Formerly, local_dict would map {'pro-duct' : 'pro-duct'} now it maps {'pro-duct' : 'product'}
<!-- END RELEASE NOTES -->

[sympy-bot]

🟠

Hi, I am the SymPy bot. I've noticed that some of your commits add or delete files. Since this is sometimes done unintentionally, I wanted to alert you about it.

This is an experimental feature of SymPy Bot. If you have any feedback on it, please comment at sympy/sympy-bot#75.

The following commits add new files:

• 180cd9f:
  • sympy/tok.py

If these files were added/deleted on purpose, you can ignore this message.

[oscarbenjamin]

I don't understand what the purpose of this is but the code is not something that we would add to sympy so I'm going to close this. Please discuss on the issue what the appropriate fix for the issue should be.