Warning raised when reading a file that doesn’t use the default ‘c’ parser.
Raised by pd.read_csv and pd.read_table when it is necessary to change
parsers, generally from the default ‘c’ parser to ‘python’.
It happens due to a lack of support or functionality for parsing a
particular attribute of a CSV file with the requested engine.
Currently, ‘c’ unsupported options include the following parameters:
sep other than a single character (e.g. regex separators)
skipfooter higher than 0
sep=None with delim_whitespace=False
The warning can be avoided by adding engine=’python’ as a parameter in
pd.read_csv and pd.read_table methods.
Read CSV (comma-separated) file into DataFrame.
Read general delimited file into DataFrame.
Using a sep in pd.read_csv other than a single character:
>>> import io
>>> csv = '''a;b;c
>>> df = pd.read_csv(io.StringIO(csv), sep='[;,]')
... # ParserWarning: Falling back to the 'python' engine...
Adding engine=’python’ to pd.read_csv removes the Warning:
>>> df = pd.read_csv(io.StringIO(csv), sep='[;,]', engine='python')