Looks through every file and finds strings that match the date format [[April 20th, 2020]] and converts them to Obsidian sort friendly format [[2020-04-20]].

roam-obsidian-date-convert.py

import re
import os
from dateutil.parser import parse

path = '' #insert file path to your vault here
for root, dirs, files in os.walk(path):
    for f in files:
        fullpath = (os.path.join(root, f))
        with open(fullpath, 'r') as f: #opens each .md file 
            contents = f.read() #reads the contexts
            #substitutes dates with the format [[April 20th, 2020]] for [[2020-04-20]]
            new_contents = re.sub(r'(?<=\[)[\w]+\s\d{1,2}\w{1,2},\s\d{4}(?=\])',
                                  lambda x: str(parse(x.group(0), ignoretz=True)).split(" ")[0], contents, flags=re.M)
        with open(fullpath, 'w') as f:
            f.write(new_contents) #writes the files with the new substitutions 

Getting an error when attempting to run on Windows in VS Code (I'm a noob).

I've attempted to include explicit encoding on open:

with open(fullpath, 'r', encoding='utf-8') as f: #opens each .md file

But still getting this error....any ideas?

Traceback (most recent call last):
  File "c:\Users\Dave Prout\github_temp\roam-obsidian-date-convert.py", line 17, in <module>
    contents = f.read() #reads the contents
  File "C:\Python39\lib\codecs.py", line 322, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 644: invalid start byte

@dbla-dprout I had to go down the same path. adding 'encoding='utf-8' did help me get further, but I was still getting the error. After adding an error exception, it was able to complete. I verified that (most) dates were converted after this fix:

with open(fullpath, 'r', encoding="utf-8", errors='ignore') as f:

There were three (of hundreds) of dates that weren't fixed, so I'll assume that they were the ones related to the encode error.