Tail / List Layer

Create a new list containing the last N elements from each variable-length list. Similar to Python's list[-n:] or R's tail(). If the input list is shorter than N, returns all available elements.

Example transformation:

With N=2:

lists	tail
[1, 2, 3, 4]	[3, 4]
[a, b, c]	[b, c]
[x]	[x]
[]	[]
[1, null, 3, null]	[3, null]

Common applications:

Extracting recent transactions
Getting latest log entries
Analyzing recent events
Viewing latest measurements
Processing most recent updates
Displaying recent activities

Note: Lists can have any length. Returns fewer elements if list length < N. Empty lists remain empty. Preserves null values within the taken range. Particularly useful for accessing recent items in time-ordered sequences.

Table

Select

column

The variable-length list column to extract from. Examples:

Recent transactions: [tx1, tx2, tx3, tx4]
System logs: [log1, log2, log3]
User actions: [click1, click2]
Sensor readings: [val1] Lists can have different lengths, including empty lists.

N

u32

Number of elements (N) to keep from end of each list. Examples:

1: Keep last element only
2: Keep last two elements
5: Keep last five elements Must be greater than 0

AsColumn

name

Name for the new column. If not provided, the system generates a unique name. If AsColumn matches an existing column, the existing column is replaced. The name should follow valid column naming conventions.