我有一个Boost多阵列,其维度是根据用户的输入在运行时设置的。
我现在想通过x,y,z
组件迭代该数组。
如果这是std :: vector,我会使用:
for(int i=0;i<v.size();i++){
或许是某种迭代器。
如何获取多阵列尺寸的数值?
如何迭代多重阵列?
谢谢!
答案 0 :(得分:11)
您可以使用shape()
来解决这种错综复杂的方式:
#include <iostream>
#include <string>
#include <boost/multi_array.hpp>
int main() {
boost::multi_array<std::string, 2> a(boost::extents[3][5]);
for(size_t x = 0; x < a.shape()[0]; x++) {
for(size_t y = 0; y < a.shape()[1]; y++) {
std::ostringstream sstr;
sstr << "[" << x << ", " << y << "]";
a[x][y] = sstr.str();
}
}
for(size_t x = 0; x < a.shape()[0]; x++) {
for(size_t y = 0; y < a.shape()[1]; y++) {
std::cout << a[x][y] << "\n";
}
}
return 0;
}
(见行动on coliru)
答案 1 :(得分:4)
#include "boost/multi_array.hpp"
#include <iostream>
#include <algorithm>
#include <iterator>
int main () {
typedef boost::multi_array_types::index_range range;
typedef boost::multi_array<char, 2> Array2d;
Array2d a(boost::extents[8][24]);
//to view the two-dimensional array as a one-dimensional one can use multi_array_ref?
boost::multi_array_ref<char, 1> a_ref(a.data(), boost::extents[a.num_elements()]);
std::fill(a_ref.begin(), a_ref.end(), '-');
//to apply algorithm to one row or column, can use array_view
//especially useful for traversing it vertically?
//e.g:
Array2d::array_view<1>::type views[4] = {
a[boost::indices[range()][0]], //left column
a[boost::indices[range()][a[0].size() - 1]], //right column
a[boost::indices[0][range()]], //top row
a[boost::indices[a.size()-1][range()]] //bottom row
};
for (unsigned i = 0; i != sizeof(views)/sizeof(views[0]); ++i) {
std::fill ( views[i].begin(), views[i].end(), 'X' );
}
//output
for (unsigned i = 0; i != a.size(); ++i) {
std::copy(a[i].begin(), a[i].end(), std::ostream_iterator<char>(std::cout, ""));
std::cout << '\n';
}
}
来源:http://cboard.cprogramming.com/cplusplus-programming/112584-boost-multiarray.html