Pandas query function not working with spaces in column names
Pandas 0.25+
As described here:
DataFrame.query()andDataFrame.eval()now supports quoting column names with backticks to refer to names with spaces (GH6508)
So you can use:
a.query('`a b`==5')Pandas pre-0.25
You cannot use pd.DataFrame.query if you have whitespace in your column name. Consider what would happen if you had columns named a, b and a b; there would be ambiguity as to what you require.
Instead, you can use pd.DataFrame.loc:
df = df.loc[df['a b'] == 5]Since you are only filtering rows, you can omit .loc accessor altogether:
df = df[df['a b'] == 5]
It is not possible yet. Check github issue #6508:
Note that in reality .query is just a nice-to-have interface, in fact it has very specific guarantees, meaning its meant to parse like a query language, and not a fully general interface.
Reason is for query need string to be a valid python expression, so column names must be valid python identifiers.
Solution is boolean indexing:
df = df[df['a b'] == 5]