Skip to main content
Version: Java (Groovy)

AggSortedFirst

AggSortedFirst returns an aggregator that sorts a table in ascending order and then computes the first value, within an aggregation group, for each input column.

note

AggSortedFirst will produce the same results as a sort operation followed by AggFirst.

Syntax​

AggSortedFirst(sortColumn, pairs...)
AggSortedFirst(sortColumns, pairs...)

Parameters​

ParameterTypeDescription
sortColumnString

The column to sort by.

pairspairs...

The input/output column name pairs.

  • "X" will output the first value in the X column for each group.
  • "Y = X" will output the first value in the X column for each group and rename it to Y.
  • "X, A = B" will output the first value in the X column for each group and the first value in the B column, while renaming it to A.
sortColumnsCollection<? extends String>

The sort column names.

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 sorts the table in ascending order and then computes the first value, within an aggregation group, for each input column.

Examples​

In this example, AggSortedFirst returns the first Y value as sorted by Z and grouped by X.

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

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", "C"),
    stringCol("Y", "N", "O", "P", "N", "P", "N", "", "Q", "O"),
    intCol("Z", 3, 2, 1, 1, 3, 1, 4, 1, 2),
)

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

In this example, AggSortedFirst returns the first Y value (renamed to Z), as sorted by Z and grouped by X.

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

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", "C"),
    stringCol("Y", "N", "O", "P", "N", "P", "N", "", "Q", "O"),
    intCol("Z", 3, 2, 1, 1, 3, 1, 4, 1, 2),
)

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

In this example, AggSortedFirst returns the first Y string and first Z integer, as sorted by Z and grouped by X.

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

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", "C"),
    stringCol("Y", "N", "O", "P", "N", "P", "N", "", "Q", "O"),
    intCol("Z", 3, 1, 2, 3, 1, 2, 4, 1, 2),
)

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

In this example, AggSortedFirst returns the first Z integer, as sorted by Z and grouped by X and Y.

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

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", "C"),
    stringCol("Y", "N", "O", "P", "N", "P", "N", "", "Q", "O"),
    intCol("Z", 3, 2, 1, 1, 3, 1, 4, 1, 2),
)

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

In this example, AggSortedFirst returns the first Y string, and AggMax returns the maximum Z integer, as sorted by Z and grouped by X.

import static io.deephaven.api.agg.Aggregation.AggSortedFirst
import static io.deephaven.api.agg.Aggregation.AggMax

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", "C"),
    stringCol("Y", "N", "O", "P", "N", "P", "N", "", "Q", "O"),
    intCol("Z", 3, 2, 1, 1, 3, 1, 4, 1, 2),
)

result = source.aggBy([AggSortedFirst("Z", "SortedFirstY = Y"),AggMax("MaxZ = Z")], "X")