Error in Rhino 8 SR31 when using pandas: unknown locale: en-US [7:1]

Grasshopper
,
18

@Timo_Harboe_Nielsen @Ukrutony

Rhino 8 has not received any changes related to handling of locales in its python environment so if Rhino 8 > SR30 is behaving differently, I am almost entirely sure this is not the scripting environment.

This is also a complicated issue where I do not control all the ends. Here are a few things to note:

  • The problem is Windows reporting BCP-47 locale names (en-US with a dash) instead of POSIX-style names (en_US with an underscore). This throws off python’s locale module on Windows and affects any python module importing the locale. pandas just happens to be the most popular one here :smiley:
  • Python 3.12+ have reworked the locale module implementation on Windows to fix this problem. So I expect we should not be seeing this in Rhino 9 that uses python 3.13
  • We shipped Rhino 8 with a system that script editor would attempt to fix the locale name on startup but I quickly realized this affects Rhino’s localization formatting since the locale is an application-wide setting.
  • So far a variation of this workaround has worked for most people.

With the help of Claude (to get more historical context on this error), I made a python module that attempts for fix this in two ways: Correct the locale name from BCP-47 to POSIX, and also override the locale.getlocale function so it does not throw exceptions.

Put this somewhere on your python search paths and import before pandas like this:

import fix_locale
import pandas

It can also be included as a Rhino startup command like:

_-ScriptEditor _R (
    #! python 3
    import fix_locale
)

Let me know if this works. If the patching of locale.getlocale resolves the problem, I can put that in Rhino permanently.

fix-locale.py (2.4 KB)