dtoolkit.transformer.QueryTF#
- class dtoolkit.transformer.QueryTF(*args, **kwargs)[source]#
A transformer query the columns of a
DataFrame
with a boolean expression.See also
pandas.DataFrame.query
This transformer’s prototype method.
Notes
query()
’sinplace
parameter is not work for this transformer. Actually this break pipeline stream. If a transformer’sinplace
isTrue
, the next tf input would getNone
.Examples
>>> import pandas as pd >>> from dtoolkit.transformer import QueryTF >>> df = pd.DataFrame( ... { ... 'A': range(1, 6), ... 'B': range(10, 0, -2), ... 'C C': range(10, 5, -1), ... }, ... ) >>> df A B C C 0 1 10 10 1 2 8 9 2 3 6 8 3 4 4 7 4 5 2 6 >>> tf = QueryTF('A > B') >>> tf.transform(df) A B C C 4 5 2 6
The previous expression is equivalent to
>>> df[df.A > df.B] A B C C 4 5 2 6
For columns with spaces in their name, you can use backtick quoting.
>>> tf = QueryTF('B == `C C`') >>> tf.transform(df) A B C C 0 1 10 10
The previous expression is equivalent to
>>> df[df.B == df['C C']] A B C C 0 1 10 10
- Attributes:
- inverse_transform_method
Methods
fit
(*_)Fit transformer.
fit_transform
(X[, y])Fit to data, then transform it.
Undo transform to
X
.set_output
(*[, transform])Set output container.
transform
(X)Transform
X
.transform_method
(self, expr, *[, inplace])Query the columns of a DataFrame with a boolean expression.
update_invargs
(*args, **kwargs)Inverse transform method argument entry.