productByKey

Multiply array elements over a given dimension, according to an array of keys. More...

Functions
AFAPI void	productByKey (array &keys_out, array &vals_out, const array &keys, const array &vals, const int dim=-1)
	C++ Interface to multiply array elements over a given dimension, according to an array of keys. More...
AFAPI void	productByKey (array &keys_out, array &vals_out, const array &keys, const array &vals, const int dim, const double nanval)
	C++ Interface to multiply array elements over a given dimension, replacing any NaNs with a specified value, according to an array of keys. More...
AFAPI af_err	af_product_by_key (af_array *keys_out, af_array *vals_out, const af_array keys, const af_array vals, const int dim)
	C Interface to multiply array elements over a given dimension, according to an array of keys. More...
AFAPI af_err	af_product_by_key_nan (af_array *keys_out, af_array *vals_out, const af_array keys, const af_array vals, const int dim, const double nanval)
	C Interface to multiply array elements over a given dimension, replacing any NaNs with a specified value, according to an array of keys. More...

Detailed Description

Multiply array elements over a given dimension, according to an array of keys.

The values corresponding to each group of consecutive equal keys will be multiplied together. Keys can repeat; however, only consecutive key values will be considered for each reduction. If a key value is repeated somewhere else in the keys array it will be considered the start of a new reduction. There are two outputs: the reduced set of consecutive keys and the corresponding final set of reduced values.

An example demonstrating the reduction behavior can be seen in the following snippet.

    array keys(9, hkeys);  // keys = [ 0 0 1 1 1 0 0 2 2 ]
    array vals(9, hvals);  // vals = [ 1 2 3 4 5 6 7 8 9 ];

    array okeys, ovals;
    productByKey(okeys, ovals, keys, vals);

    // okeys = [ 0  1  0  2 ]
    // ovals = [ 2 60 42 72 ]

The keys' input type must be integer (s32 or u32).

This table defines output types for corresponding input types:

Input Type	Output Type -----—
f32, f64, c32, c64	same as input
s32, u32, s64, u64	same as input
s16	s32
u16, u8, b8	u32
f16	f32

The keys array must be 1-dimenstional matching the size of the reduced dimension. An example of multi-dimensional reduce-by-key can be seen below:

    array keys(5, hkeys);
    array vals(2, 5, hvals);

    // keys = [ 1 0 0 2 2 ]

    // vals = [[ 1 2 3 4 5  ]
    //         [ 6 7 8 9 10 ]]

    const int reduce_dim = 1;
    array okeys, ovals;
    productByKey(okeys, ovals, keys, vals, reduce_dim);

    // okeys = [ 1 0 2 ]

    // ovals = [[ 1  6 20 ],
    //          [ 6 56 90 ]]

Function Documentation

af_product_by_key()

AFAPI af_err af_product_by_key	(	af_array *	keys_out,
		af_array *	vals_out,
		const af_array	keys,
		const af_array	vals,
		const int	dim
	)

C Interface to multiply array elements over a given dimension, according to an array of keys.

Parameters

[out]	keys_out	reduced keys
[out]	vals_out	product
[in]	keys	keys array
[in]	vals	input array
[in]	dim	dimension along which the product occurs

Returns

AF_SUCCESS, if function returns successfully, else an af_err code is given

af_product_by_key_nan()

AFAPI af_err af_product_by_key_nan	(	af_array *	keys_out,
		af_array *	vals_out,
		const af_array	keys,
		const af_array	vals,
		const int	dim,
		const double	nanval
	)

C Interface to multiply array elements over a given dimension, replacing any NaNs with a specified value, according to an array of keys.

Parameters

[out]	keys_out	reduced keys
[out]	vals_out	product
[in]	keys	keys array
[in]	vals	input array
[in]	dim	dimension along which the product occurs
[in]	nanval	value that replaces NaNs

Returns

AF_SUCCESS, if function returns successfully, else an af_err code is given

productByKey() [1/2]

AFAPI void af::productByKey	(	array &	keys_out,
		array &	vals_out,
		const array &	keys,
		const array &	vals,
		const int	dim = -1
	)

C++ Interface to multiply array elements over a given dimension, according to an array of keys.

Parameters

[out]	keys_out	reduced keys
[out]	vals_out	product
[in]	keys	keys array
[in]	vals	input array
[in]	dim	dimension along which the product occurs, -1 denotes the first non-singleton dimension

productByKey() [2/2]

AFAPI void af::productByKey	(	array &	keys_out,
		array &	vals_out,
		const array &	keys,
		const array &	vals,
		const int	dim,
		const double	nanval
	)

C++ Interface to multiply array elements over a given dimension, replacing any NaNs with a specified value, according to an array of keys.

Parameters

[out]	keys_out	reduced keys
[out]	vals_out	product
[in]	keys	keys array
[in]	vals	input array
[in]	dim	dimension along which the product occurs
[in]	nanval	value that replaces NaNs