Group pairs of items according to the first element of the pair:

Group values of an association:

Group by the first element and compute the mean of the corresponding last elements:

Group the elements repeatedly by using several functions:

Group last parts of pairs according to the first part:

Group values of an association by using several functions:

Use a symbolic selector for grouping:

Pairs for which the selector yields the same value are grouped under the same key:

Use different functions to extract keys and values:

Use the operator form of Extract to specify the key or the value:

Use a combiner function to combine the values:

Group associations according to the value of their first element:

Group associations according to the value of the given key:

Specify keys and values using Key:

Missing keys are replaced with Missing:

Group a list of integers by positivity and parity, displaying the groups as column vectors:

Use the operator form of GroupBy:

Group results of applying a function to values of an association:

Use GroupBy to group rows in a dataset, introducing new levels of association:

Group the passengers by class:

Group the passengers by sex and then class:

GroupBy returns an association, while GatherBy returns a list:

Grouping by f is equivalent to grouping by fIdentity:

Counts[expr] is equivalent to GroupBy[expr,Identity,Length]:

CountsBy[expr,f] is equivalent to GroupBy[expr,f,Length]: