Len / List Layer

Calculate the number of elements in each variable-length list. Similar to Python's len() or R's length(). Returns an integer column containing the count of elements in each list.

Example transformation:

lists	length
[1, 2, 3, 4]	4
[a, b]	2
[true]	1
[1, null, 3, null]	4
[]	0

Common applications:

Analyzing sequence lengths
Validating list sizes
Counting event occurrences
Measuring transaction volumes
Monitoring data completeness
Analyzing interaction frequencies

Note: Counts all elements including nulls. Empty lists return 0. Useful for analyzing the size distribution of variable-length data or identifying unusually long or short sequences.

Table

Select

column

The variable-length list column to measure. Examples:

Transaction histories: [t1, t2, t3]
User interactions: [click1, click2]
Time series samples: [1.1, 1.2, 1.3, 1.4]
Event sequences: [event1] Lists can have different lengths, including empty lists

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.