Documentation
Group By
Grouping is a common operation in data analysis. The concept is no different from the one you know from SQL.
To group data you need to use DataFrame::groupBy function.
Example:
data_frame()
->read(from_array([
['id' => 1, 'group' => 'A'],
['id' => 2, 'group' => 'B'],
['id' => 3, 'group' => 'A'],
['id' => 4, 'group' => 'B'],
['id' => 5, 'group' => 'A'],
['id' => 6, 'group' => 'B'],
['id' => 7, 'group' => 'A'],
['id' => 8, 'group' => 'B'],
['id' => 9, 'group' => 'A'],
['id' => 10, 'group' => 'B'],
]))
->groupBy(ref('group'))
->write(to_output(truncate: false))
->run();
However, the result of this operation is not very useful. It will just return a DataFrame with one column group:
+-------+
| group |
+-------+
| A |
| B |
+-------+
2 rows
To make it more useful, you need to use one of the aggregation functions.
Examples
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