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Version: Java (Groovy)

headBy

headBy returns the first n rows for each group.

Syntax​

table.headBy(nRows, groupByColumnNames...)

Parameters​

ParameterTypeDescription
nRowslong

The number of rows to return for each group.

groupByColumnNamesString...

The column(s) by which to group data.

  • "X" will output the entire first n row(s) of each group in column X.
  • "X", "Y" will output the entire first n row(s) of each group designated from the X and Y columns.
groupByColumnNamesCollection<String>

The column(s) by which to group data.

  • "X" will output the entire first n row(s) of each group in column X.
  • "X", "Y" will output the entire first n row(s) of each group designated from the X and Y columns.

Returns​

A new table containing the first n rows for each group.

Examples​

In this example, headBy returns the first 2 rows, as grouped by X.

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

result = source.headBy(2, "X")

In this example, headBy returns the first 2 rows, as grouped by X and Y.

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

result = source.headBy(2, "X", "Y")