Template Function thrust::gather(InputIterator, InputIterator, RandomAccessIterator, OutputIterator)¶
Function Documentation¶
-
template<typename
InputIterator
, typenameRandomAccessIterator
, typenameOutputIterator
>
OutputIteratorthrust
::
gather
(InputIterator map_first, InputIterator map_last, RandomAccessIterator input_first, OutputIterator result) gather
copies elements from a source array into a destination range according to a map. For each input iteratori
in the range[map_first, map_last)
, the valueinput_first[*i]
is assigned to*(result + (i - map_first))
.RandomAccessIterator
must permit random access.The following code snippet demonstrates how to use
gather
to reorder a range.- Pre
The range
[map_first, map_last)
shall not overlap the range[result, result + (map_last - map_first))
.- Remark
gather
is the inverse of thrust::scatter.- Parameters
map_first
: Beginning of the range of gather locations.map_last
: End of the range of gather locations.input_first
: Beginning of the source range.result
: Beginning of the destination range.
- Template Parameters
InputIterator
: must be a model of Input Iterator andInputIterator's
value_type
must be convertible toRandomAccessIterator's
difference_type
.RandomAccessIterator
: must be a model of Random Access Iterator andRandomAccessIterator's
value_type
must be convertible toOutputIterator's
value_type
.OutputIterator
: must be a model of Output Iterator.
#include <thrust/gather.h> #include <thrust/device_vector.h> ... // mark even indices with a 1; odd indices with a 0 int values[10] = {1, 0, 1, 0, 1, 0, 1, 0, 1, 0}; thrust::device_vector<int> d_values(values, values + 10); // gather all even indices into the first half of the range // and odd indices to the last half of the range int map[10] = {0, 2, 4, 6, 8, 1, 3, 5, 7, 9}; thrust::device_vector<int> d_map(map, map + 10); thrust::device_vector<int> d_output(10); thrust::gather(d_map.begin(), d_map.end(), d_values.begin(), d_output.begin()); // d_output is now {1, 1, 1, 1, 1, 0, 0, 0, 0, 0}