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Version: Python

count_

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

note

count is a reserved Python keyword, so an underscore is used to maintain Python conventions.

Syntax​

count_(col: str) -> Aggregation

Parameters​

ParameterTypeDescription
colstr

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"), agg.avg(cols="AvgNum = Number")], by=["X"]
)