productByKey

Finds the product of an input array 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 for product of elements in an array according to a key.
AFAPI void	productByKey (array &keys_out, array &vals_out, const array &keys, const array &vals, const int dim, const double nanval)
	C++ Interface for product of elements in an array according to a key while replacing nan values.
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 for product of elements in an array according to key.
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 for product of elements in an array according to key while replacing nans.

Detailed Description

Finds the product of an input array 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 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 an integer type(s32 or u32). This table defines the return types for the corresponding values type

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 input keys must be a 1-D vector matching the size of the reduced dimension. In the case of multiple dimensions in the input values array, the dim parameter specifies which dimension to reduce along. 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 for product of elements in an array according to key.

Parameters

[out]	keys_out	will contain the reduced keys in vals along dim
[out]	vals_out	will contain the product of all values in vals along dim according to keys
[in]	keys	is the key array
[in]	vals	is the array containing the values to be reduced
[in]	dim	The dimension along which the product operation occurs

Returns

AF_SUCCESS if the execution completes properly

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 for product of elements in an array according to key while replacing nans.

Parameters

[out]	keys_out	will contain the reduced keys in vals along dim
[out]	vals_out	will contain the product of all values in vals along dim according to keys
[in]	keys	is the key array
[in]	vals	is the array containing the values to be reduced
[in]	dim	The dimension along which the product operation occurs
[in]	nanval	The value that will replace the NaNs in vals

Returns

AF_SUCCESS if the execution completes properly

productByKey() [1/2]

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

C++ Interface for product of elements in an array according to a key while replacing nan values.

Parameters

[out]	keys_out	will contain the reduced keys in vals along dim
[out]	vals_out	will contain the product of all values in vals along dim according to keys
[in]	keys	is the key array
[in]	vals	is the array containing the values to be reduced
[in]	dim	The dimension along which the product operation occurs
[in]	nanval	The value that will replace the NaNs in vals

productByKey() [2/2]

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

C++ Interface for product of elements in an array according to a key.

Parameters

[out]	keys_out	will contain the reduced keys in vals along dim
[out]	vals_out	will contain the product of all values in vals along dim according to keys
[in]	keys	The key array
[in]	vals	The array containing the values to be reduced
[in]	dim	The dimension along which the product operation occurs

Note

dim is -1 by default. -1 denotes the first non-singleton dimension.