Concat / List Layer

Concatenate elements from two list columns into a single list. Similar to Python's list1 + list2 or R's c() function. Creates a new list column containing all elements from the left list followed by all elements from the right list.

Example transformation:

left_list	right_list	result
[1, 2]	[3, 4, 5]	[1, 2, 3, 4, 5]
[red, blue]	[green]	[red, blue, green]
[10]	[]	[10]
[]	[20, 30]	[20, 30]
[1, null, 3]	[4, 5]	[1, null, 3, 4, 5]

Common applications:

Combining historical and current data
Merging multiple tag sets
Building composite time series
Joining sequential measurements
Creating aggregate feature lists
Combining multi-source observations

Note: Lists can have different lengths. Null values are preserved in the concatenated result. Empty lists are valid inputs. Both input lists must be of the same type (e.g., both numeric or both string).

Table

SelectLeft

column

The first list column (SelectLeft) to concatenate. Common patterns:

Historical data: [old_value1, old_value2]
Primary tags: [tag1, tag2]
Base features: [feature1, feature2] Can be empty list. Must match type with right list.

SelectRight

column

The second list column (SelectRight) to concatenate. Common patterns:

New data: [new_value1, new_value2]
Secondary tags: [tag3, tag4]
Additional features: [feature3, feature4] Can be empty list. Must match type with left list.

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.