af_sort

The C interface for sort. More...

Device pointer interface: Sort the input values
Sort an array of values along specified dimension. Output both values and indices. Parameters [out] d_sorted Sorted values [out] d_Indices Indices indicating original positions. One indexed [in] ndims Number of dimensions in dims [in] dims Dimensions of input [in] d_input Original array values [in] DIR Sort direction: true in descending order, false in ascending order. [in] dim Dimension to sort along (first dimension is zero) [in] batch Number of tiles in batch. [in] base_one To shift indices to one-based.
afError	af_sort_S (float *d_sorted, float *d_Indices, unsigned ndims, const unsigned *dims, float *d_input, bool DIR, unsigned dim, unsigned batch, bool base_one=false)
	Single-precision sort. More...
afError	af_sort_D (double *d_sorted, double *d_Indices, unsigned ndims, const unsigned *dims, double *d_input, bool DIR, unsigned dim, unsigned batch, bool base_one=false)
	Double-precision sort. More...
afError	af_sort_I (int *d_sorted, int *d_Indices, unsigned ndims, const unsigned *dims, int *d_input, bool DIR, unsigned dim, unsigned batch, bool base_one=false)
	32-bit Integer sort. More...
afError	af_sort_U (unsigned *d_sorted, unsigned *d_Indices, unsigned ndims, const unsigned *dims, unsigned *d_input, bool DIR, unsigned dim, unsigned batch, bool base_one=false)
	32-bit Unsigned Integer sort. More...

Detailed Description

The C interface for sort.

Sorting an array reorders the elements in the array along the dimension specified.

The defualt order is ascending order. That is, the smallest element along the dimension is places at the first index location and the largest element is placed at the last location. To sort in descending order, set the isdescending flag to true.

The indices array parameter can be used to retrieve the indices of the elements before the sort.

array a = rand(5); //a = [6]
                   //    [9]
                   //    [1]
                   //    [7]
                   //    [4]

a = sort(a,0);     //a = [1]
                   //    [4]
                   //    [6]
                   //    [7]
                   //    [9]

array a = rand(5); //a = [6]
                   //    [9]
                   //    [1]
                   //    [7]
                   //    [4]

array out,indices;
sort(out,indices,a,0);
     //out,indices = [1],[2]
     //              [4],[4]
     //              [6],[0]
     //              [7],[3]
     //              [9],[1]

The next sort function can sort the values of an array (value) based on another array (key). The function first sorts the key array and uses the indices from this sort to reorder the value array.

float keys[]   = {1, 6, 2, 5, 3, 4};

array value(6,1,values); // [5 10 41  2  5  7]
array key(6,1,keys);     // [1  6  2  5  3  4]

array outkeys,outvalues;
sort(outkeys,outvalues,key,value);

print(outvalues); // [5 41  5  7  2 10]
print(outkeys);   // [1  2  3  4  5  6]

The function sortdim uses one of the dimensions as key to sort the array.

// sort rows based on first column
array a = floor(5 * randu(5,5));
array b = sortdim(a);

array a = floor(5 * randu(5,5));
const int order[] = {3, 1};
array d = sortdim(a, 0, 2, order);

Function Documentation

afError af_sort_S	(	float *	d_sorted,
		float *	d_Indices,
		unsigned	ndims,
		const unsigned *	dims,
		float *	d_input,
		bool	DIR,
		unsigned	dim,
		unsigned	batch,
		bool	base_one = false
	)

Single-precision sort.

afError af_sort_D	(	double *	d_sorted,
		double *	d_Indices,
		unsigned	ndims,
		const unsigned *	dims,
		double *	d_input,
		bool	DIR,
		unsigned	dim,
		unsigned	batch,
		bool	base_one = false
	)

Double-precision sort.

afError af_sort_I	(	int *	d_sorted,
		int *	d_Indices,
		unsigned	ndims,
		const unsigned *	dims,
		int *	d_input,
		bool	DIR,
		unsigned	dim,
		unsigned	batch,
		bool	base_one = false
	)

32-bit Integer sort.

afError af_sort_U	(	unsigned *	d_sorted,
		unsigned *	d_Indices,
		unsigned	ndims,
		const unsigned *	dims,
		unsigned *	d_input,
		bool	DIR,
		unsigned	dim,
		unsigned	batch,
		bool	base_one = false
	)

32-bit Unsigned Integer sort.