FutureWarning: The default value of regex will change from True to False in a future version

I’m running below code to clean text

import pandas as pd

def not_regex(pattern):
        return r"((?!{}).)".format(pattern)
    
tmp = pd.DataFrame(['No one has a European accent either @',
                    'That the kid   reminds me of Kevin'])

tmp[0].str.replace(not_regex('(\b[-/]\b|[a-zA-Z0-9])'), ' ') 

Then it returns a warning

<ipython-input-8-ef8a43f91dbd>:9: FutureWarning: The default value of regex will change from True to False in a future version.
  tmp[0].str.replace(not_regex('(\b[-/]\b|[a-zA-Z0-9])'), ' ')

Could you please elaborate on the reason of this warning?

Answer

See Pandas 1.2.0 release notes:

The default value of regex for Series.str.replace() will change from True to False in a future release. In addition, single character regular expressions will not be treated as literal strings when regex=True is set (GH24804)

I.e., use regular expressions explicitly now:

dframe['colname'] = dframe['colname'].str.replace(r'D+', regex=True)