pandas.errors.ParserWarning

exception pandas.errors.ParserWarning

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:

1. sep other than a single character (e.g. regex separators)
2. skipfooter higher than 0
3. 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.

See also

pd.read_csv

Read CSV (comma-separated) file into DataFrame.

pd.read_table

Read general delimited file into DataFrame.

Examples

Using a sep in pd.read_csv other than a single character:

>>> import io
>>> csv = '''a;b;c
...           1;1,8
...           1;2,1'''
>>> df = pd.read_csv(io.StringIO(csv), sep='[;,]')  # doctest: +SKIP
... # 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')