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Version: Java (Groovy)

AggDistinct

AggDistinct returns an aggregator that computes a set of distinct values within an aggregation group, for each input column.

Syntax​

AggDistinct(includeNulls, pairs...)
AggDistinct(pairs...)

Parameters​

ParameterTypeDescription
includeNullsboolean

If true, then null values are included in the result; otherwise null values are ignored. The default value is false.

pairsString...

The source column(s) for the calculations.

  • "X" will output the set of distinct values in the X column for each group.
  • "Y = X" will output the set of distinct values in the X column for each group and rename it to "Y".
  • "X, A = B" will output the set of distinct values in the X column for each group and the set of distinct values in the B value column renaming it to A.
caution

If an aggregation does not rename the resulting column, the aggregation column will appear in the output table, not the input column. If multiple aggregations on the same column do not rename the resulting columns, an error will result, because the aggregations are trying to create multiple columns with the same name. For example, in table.aggBy([agg.AggSum(“X”), agg.AggAvg(“X”)]), both the sum and the average aggregators produce column X, which results in an error.

Returns​

An aggregator that computes a set of distinct values, within an aggregation group, for each input column.

Examples​

In this example, AggDistinct returns the distinct set of values of Y as grouped by X. includeNulls is true and null values are included.

import static io.deephaven.api.agg.Aggregation.AggDistinct

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", null),
    stringCol("Y", "M", "N", null, "N", "P", "M", null, "P", "M"),
    intCol("Number", 55, 76, 20, 130, 230, 50, 73, 137, 214),
)

result = source.aggBy([AggDistinct(true, "Y")], "X")

In this example, AggDistinct returns the distinct set of values of Y as grouped by X. includeNulls is false and null values are ignored.

import static io.deephaven.api.agg.Aggregation.AggDistinct

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", null),
    stringCol("Y", "M", "N", null, "N", "P", "M", null, "P", "M"),
    intCol("Number", 55, 76, 20, 130, 230, 50, 73, 137, 214),
)

result = source.aggBy([AggDistinct(false, "Y")], "X")

In this example, AggDistinct returns the distinct set of values of Y (renamed to Z), as grouped by X. includeNulls is true and null values are included.

import static io.deephaven.api.agg.Aggregation.AggDistinct

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", null),
    stringCol("Y", "M", "N", null, "N", "P", "M", null, "P", "M"),
    intCol("Number", 55, 76, 20, 130, 230, 50, 73, 137, 214),
)

result = source.aggBy([AggDistinct(true, "Z = Y")], "X")

In this example, AggDistinct returns the distinct set of values of Y (renamed to Z), as grouped by X. includeNulls is false and null values are ignored. Also, AggLast returns the last Number integer, as grouped by X.

import static io.deephaven.api.agg.Aggregation.AggDistinct

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", null),
    stringCol("Y", "M", "N", null, "N", "P", "M", null, "P", "M"),
    intCol("Number", 55, 76, 20, 130, 230, 50, 73, 137, 214),
)

result = source.aggBy([AggDistinct(false, "Z = Y")], "X")