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Version: Python

count

agg.count_ returns an aggregator that computes the number of elements within an aggregation group.

Syntax

count_(col: str)

Parameters

ParameterTypeDescription
colString

The name of the output column that will contain the number of elements in each group.

Returns

An aggregator that computes the number of elements within an aggregation group, for each group.

Examples

In this example, agg.count adds a count column, Number, while agg.avgreturns the average Number, as grouped by X.

from deephaven import new_table
from deephaven.column import string_col, int_col, double_col
from deephaven import agg as agg

source = new_table([
string_col("X", ["A", "B", "A", "C", "B", "A", "B", "B", "C"]),
string_col("Y", ["M", "P", "O", "N", "P", "M", "O", "P", "N"]),
int_col("Number", [55, 76, 20, 130, 230, 50, 73, 137, 214]),
])

result = source.agg_by([agg.count_(col="Number")], by=["X"])