array_iff

The array_iff function in Axiom Processing Language (APL) allows you to create arrays based on a condition. It returns an array with elements from two specified arrays, choosing each element from the first array when a condition is met and from the second array otherwise. This function is useful for scenarios where you need to evaluate a series of conditions across multiple datasets, especially in log analysis, trace data, and other applications requiring conditional element selection within arrays.

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For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

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Usage

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Syntax

array_iff(condition_array, array1, array2)

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Parameters

• condition_array: An array of boolean values, where each element determines whether to choose the corresponding element from array1 or array2.
• array1: The array to select elements from when the corresponding condition_array element is true.
• array2: The array to select elements from when the corresponding condition_array element is false.

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Returns

An array where each element is selected from array1 if the corresponding condition_array element is true, and from array2 otherwise.

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Use case examples

• Log analysis
• OpenTelemetry traces
• Security logs

['sample-http-logs']
| order by _time desc
| limit 1000
| summarize is_ok = make_list(status == '200'), request_duration = make_list(req_duration_ms)
| project ok_request_duration = array_iff(is_ok, request_duration, 0)

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List of related functions

• array_slice: Extracts a subset of elements from an array.
• array_concat: Combines multiple arrays.
• array_rotate_right: Rotates array elements to the right by a specified number of positions.