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Version: Python

tail_by

tail_by returns the last n rows for each group.

Syntax

table.tail_by(n: int, by: List[str]=[])

Parameters

ParameterTypeDescription
nint

The number of rows to return for each group.

by optionalList[str]

The column(s) by which to group data.

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

Returns

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

Examples

In this example, tail_by returns the last 2 rows, as grouped by X.

from deephaven import new_table
from deephaven.column import string_col, int_col

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

result = source.tail_by(2, by=["X"])

In this example, tail_by returns the last 2 rows, as grouped by X and Y.

from deephaven import new_table
from deephaven.column import string_col, int_col

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

result = source.tail_by(2, by=["X", "Y"])