set_difference

Use the set_difference function in APL to compute the distinct elements in one array that aren’t present in another. This function helps you filter out shared values between two arrays, producing a new array that includes only the unique values from the first input array.

Use set_difference when you need to identify new or missing elements, such as:

• Users who visited today but not yesterday.
• Error codes that occurred in one region but not another.
• Service calls that appear in staging but not production.

Usage#

Syntax#

set_difference(Array1, Array2)

Parameters#

Returns#

An array that includes all values from Array1 that aren’t present in Array2. The result doesn’t include duplicates.

Example#

Use set_difference to return the difference between two arrays.

Query

['sample-http-logs']
| extend difference = set_difference(dynamic([1, 2, 3]), dynamic([2, 3, 4, 5]))

Run in Playground

Output

List of related functions#

• set_has_element: Tests whether a set contains a specific value. Prefer it when you only need a Boolean result.
• set_union: Returns the union of two or more sets. Use it when you need any element that appears in at least one set instead of every set.

Other query languages#