80 lines
2.4 KiB
Plaintext
80 lines
2.4 KiB
Plaintext
|
#include <thrust/device_vector.h>
|
||
|
|
#include <thrust/functional.h>
|
||
|
|
#include <thrust/host_vector.h>
|
||
|
|
#include <thrust/inner_product.h>
|
||
|
|
#include <thrust/reduce.h>
|
||
|
|
|
||
|
|
#include <cuda/std/iterator> // Required for std::begin/std::end
|
||
|
|
|
||
|
|
#include <iostream>
|
||
|
|
|
||
|
|
// This example computes the number of words in a text sample
|
||
|
|
// with a single call to thrust::inner_product. The algorithm
|
||
|
|
// counts the number of characters which start a new word, i.e.
|
||
|
|
// the number of characters where input[i] is an alphabetical
|
||
|
|
// character and input[i-1] is not an alphabetical character.
|
||
|
|
|
||
|
|
// determines whether the character is alphabetical
|
||
|
|
__host__ __device__ bool is_alpha(const char c)
|
||
|
|
{
|
||
|
|
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
|
||
|
|
}
|
||
|
|
|
||
|
|
int word_count(const thrust::device_vector<char>& input)
|
||
|
|
{
|
||
|
|
// check for empty string
|
||
|
|
if (input.empty())
|
||
|
|
{
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
// determines whether the right character begins a new word
|
||
|
|
auto is_word_start = [] __host__ __device__(const char& left, const char& right) {
|
||
|
|
return is_alpha(right) && !is_alpha(left);
|
||
|
|
};
|
||
|
|
|
||
|
|
// compute the number characters that start a new word
|
||
|
|
int wc = thrust::inner_product(
|
||
|
|
input.begin(),
|
||
|
|
input.end() - 1, // sequence of left characters
|
||
|
|
input.begin() + 1, // sequence of right characters
|
||
|
|
0, // initialize sum to 0
|
||
|
|
cuda::std::plus<int>{}, // sum values together
|
||
|
|
is_word_start // how to compare the left and right characters
|
||
|
|
);
|
||
|
|
|
||
|
|
// if the first character is alphabetical, then it also begins a word
|
||
|
|
if (is_alpha(input.front()))
|
||
|
|
{
|
||
|
|
wc++;
|
||
|
|
}
|
||
|
|
|
||
|
|
return wc;
|
||
|
|
}
|
||
|
|
|
||
|
|
int main()
|
||
|
|
{
|
||
|
|
// Paragraph from 'The Raven' by Edgar Allan Poe
|
||
|
|
// http://en.wikipedia.org/wiki/The_Raven
|
||
|
|
const char raw_input[] =
|
||
|
|
" But the raven, sitting lonely on the placid bust, spoke only,\n"
|
||
|
|
" That one word, as if his soul in that one word he did outpour.\n"
|
||
|
|
" Nothing further then he uttered - not a feather then he fluttered -\n"
|
||
|
|
" Till I scarcely more than muttered `Other friends have flown before -\n"
|
||
|
|
" On the morrow he will leave me, as my hopes have flown before.'\n"
|
||
|
|
" Then the bird said, `Nevermore.'\n";
|
||
|
|
|
||
|
|
std::cout << "Text sample:\n";
|
||
|
|
std::cout << raw_input << "\n";
|
||
|
|
|
||
|
|
// transfer to device
|
||
|
|
thrust::device_vector<char> input(cuda::std::begin(raw_input), cuda::std::end(raw_input));
|
||
|
|
|
||
|
|
// count words
|
||
|
|
int wc = word_count(input);
|
||
|
|
|
||
|
|
std::cout << "Text sample contains " << wc << " words\n";
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|