select

Selects elements from two arrays based on the values of a binary conditional array. More...

Functions
AFAPI array	select (const array &cond, const array &a, const array &b)
AFAPI array	select (const array &cond, const array &a, const double &b)
AFAPI array	select (const array &cond, const double &a, const array &b)
AFAPI af_err	af_select (af_array *out, const af_array cond, const af_array a, const af_array b)
AFAPI af_err	af_select_scalar_r (af_array *out, const af_array cond, const af_array a, const double b)
AFAPI af_err	af_select_scalar_l (af_array *out, const af_array cond, const double a, const af_array b)

Detailed Description

Selects elements from two arrays based on the values of a binary conditional array.

Creates a new array that is composed of values either from array a or array b, based on a third conditional array. For all non-zero elements in the conditional array, the output array will contain values from a. Otherwise the output will contain values from b.

    int elements = 9;
    char hCond[] = {1, 0, 1, 0, 1, 0, 1, 0, 1};
    float hA[]   = {2, 2, 2, 2, 2, 2, 2, 2, 2};
    float hB[]   = {3, 3, 3, 3, 3, 3, 3, 3, 3};
 
    array cond(elements, hCond);
    array a(elements, hA);
    array b(elements, hB);
 
    array out = select(cond, a, b);
    // out = {2, 3, 2, 3, 2, 3, 2, 3, 2};

is equivalent to:

    vector<float> hOut(elements);
    for (size_t i = 0; i < hOut.size(); i++) {
        if (hCond[i]) {
            hOut[i] = hA[i];
        } else {
            hOut[i] = hB[i];
        }
    }

The conditional array must be a b8 typed array.

The select function can perform batched operations based on the size of each of the inputs. The following table describes the input and output sizes for supported batched configurations.

Output	Condition Array	Array A	Array B
(M, N)	(M, 1)	(M, 1)	(M, N)
(M, N)	(M, 1)	(M, N)	(M, 1)
(M, N)	(M, 1)	(M, N)	(M, N)
(M, N)	(M, N)	(M, 1)	(M, N)
(M, N)	(M, N)	(M, 1)	(M, N)

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Function Documentation

af_select()

AFAPI af_err af_select	(	af_array *	out,
		const af_array	cond,
		const af_array	a,
		const af_array	b
	)

Parameters

[out]	out	is the output containing elements of a when cond is true else elements from b
[in]	cond	is the conditional array
[in]	a	is the array containing elements from the true part of the condition
[in]	b	is the array containing elements from the false part of the condition

af_select_scalar_l()

AFAPI af_err af_select_scalar_l	(	af_array *	out,
		const af_array	cond,
		const double	a,
		const af_array	b
	)

Parameters

[out]	out	is the output containing elements of a when cond is true else elements from b
[in]	cond	is the conditional array
[in]	a	is a scalar assigned to out when cond is true
[in]	b	is the array containing elements from the false part of the condition

af_select_scalar_r()

AFAPI af_err af_select_scalar_r	(	af_array *	out,
		const af_array	cond,
		const af_array	a,
		const double	b
	)

Parameters

[out]	out	is the output containing elements of a when cond is true else elements from b
[in]	cond	is the conditional array
[in]	a	is the array containing elements from the true part of the condition
[in]	b	is a scalar assigned to out when cond is false

select() [1/3]

AFAPI array af::select	(	const array &	cond,
		const array &	a,
		const array &	b
	)

Parameters

[in]	cond	is the conditional array
[in]	a	is the array containing elements from the true part of the condition
[in]	b	is the array containing elements from the false part of the condition

Returns

the output containing elements of a when cond is true else elements from b

select() [2/3]

AFAPI array af::select	(	const array &	cond,
		const array &	a,
		const double &	b
	)

Parameters

[in]	cond	is the conditional array
[in]	a	is the array containing elements from the true part of the condition
[in]	b	is a scalar assigned to out when cond is false

Returns

the output containing elements of a when cond is true else the value b

select() [3/3]

AFAPI array af::select	(	const array &	cond,
		const double &	a,
		const array &	b
	)

Parameters

[in]	cond	is the conditional array
[in]	a	is a scalar assigned to out when cond is true
[in]	b	is the array containing elements from the false part of the condition

Returns

the output containing the value a when cond is true else elements from b