Subarray function

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Warning

This documentation refers to the Classic QDK, which has been replaced by the Modern QDK.

Please see https://aka.ms/qdk.api for the API documentation for the Modern QDK.

Namespace: Microsoft.Quantum.Arrays

Package: Microsoft.Quantum.Standard

Takes an array and a list of locations and produces a new array formed from the elements of the original array that match the given locations.

function Subarray<'T> (indices : Int[], array : 'T[]) : 'T[]

Input

indices : Int[]

A list of integers that is used to define the subarray.

array : 'T[]

An array of elements over 'T.

Output : 'T[]

An array out of elements whose indices correspond to the subarray, such that out[idx] == array[indices[idx]].

Type Parameters

'T

The type of array elements.

Example

open Microsoft.Quantum.Arrays;

function SubarrayDemo() : Unit {
    let array = [1, 2, 3, 4];
    let permutation = Subarray([3, 0, 2, 1], array); // [4, 1, 3, 2]
    let duplicates = Subarray([1, 2, 2], array);     // [2, 3, 3]
}

Remarks

The function is defined for generic types, i.e., whenever we have an array 'T[] and a list of locations Int[] defining the subarray. The construction of the subarray is a based on generating a new, deep copy of the given array as opposed to maintaining references.

If indices contains repeated elements, the corresponding elements of array will likewise be repeated. If all elements of indices are unique, this function will return a subset of array if Length(indices) < Length(array), or a permutation of array if indices and array are of the same length.