DataFrame.groupby()

pandas.DataFrame.groupby

DataFrame.groupby(by=None, axis=0, level=None, as_index=True, sort=True, group_keys=True, squeeze=False, **kwargs) [source]

Group series using mapper (dict or key function, apply given function to group, return result as series) or by a series of columns.

Parameters:

by : mapping, function, str, or iterable Used to determine the groups for the groupby. If by is a function, it’s called on each value of the object’s index. If a dict or Series is passed, the Series or dict VALUES will be used to determine the groups (the Series’ values are first aligned; see .align() method). If an ndarray is passed, the values are used as-is determine the groups. A str or list of strs may be passed to group by the columns in self axis : int, default 0 level : int, level name, or sequence of such, default None If the axis is a MultiIndex (hierarchical), group by a particular level or levels as_index : boolean, default True For aggregated output, return object with group labels as the index. Only relevant for DataFrame input. as_index=False is effectively “SQL-style” grouped output sort : boolean, default True Sort group keys. Get better performance by turning this off. Note this does not influence the order of observations within each group. groupby preserves the order of rows within each group. group_keys : boolean, default True When calling apply, add group keys to index to identify pieces squeeze : boolean, default False reduce the dimensionality of the return type if possible, otherwise return a consistent type

Returns:

GroupBy object

Examples

DataFrame results

>>> data.groupby(func, axis=0).mean()
>>> data.groupby(['col1', 'col2'])['col3'].mean()

DataFrame with hierarchical index

>>> data.groupby(['col1', 'col2']).mean()