`bit::matrix` — Extract a Sub-Bit-Matrix

We have methods to extract a sub-matrix as a stand-alone, distinct copy of elements from this bit-matrix.

constexpr bit::matrix
1sub(std::size_t i0, std::size_t j0, std::size_t r, std::size_t c) const;

constexpr bit::matrix
2sub(std::size_t r, std::size_t c) const;

constexpr bit::matrix
3sub(std::size_t n) const const;

1: Returns an r x c bit-matrix, a copy from this bit-matrix starting at (i0, j0)
2: Returns an r x c bit-matrix, a copy from this bit-matrix starting at (0, 0).
3: Returns an n x n square bit-matrix, a copy from this bit-matrix starting at (0, 0)

(i0, j0) has to be a valid index pair, and the requested dimensions must fit as a valid sub-matrix. Set the BIT_VERIFY flag at compile time to check these conditions — any violation will cause the program to abort with a helpful message.

Example

#include <bit/bit.h>
int main()
{
1    auto m = bit::matrix<>::random(8);
    std::cout << "m:                \n" << m                << "\n";
2    std::cout << "m.sub(4):         \n" << m.sub(4)         << "\n";
3    std::cout << "m.sub(2,4):       \n" << m.sub(2,4)       << "\n";
4    std::cout << "m.sub(5,5,3,3):   \n" << m.sub(5,5,3,3)   << "\n";
}

1: This constructs an 8 x 8 bit-matrix a random fill.
2: Extract the 4 x 4 elements starting at index (0, 0).
3: Extract the 2 x 4 elements starting at index (0, 0).
4: Extract the 3 x 3 elements starting at index (5, 5).

Output

m:
│0 1 0 0 1 1 0 1│
│1 0 1 1 0 0 1 1│
│1 0 0 0 0 0 0 1│
│0 0 0 0 1 0 1 1│
│0 0 1 1 0 1 0 0│
│0 0 0 1 0 0 0 0│
│1 1 1 0 1 1 0 1│
│1 1 1 1 1 0 0 1│
m.sub(4):
│0 1 0 0│
│1 0 1 1│
│1 0 0 0│
│0 0 0 0│
m.sub(2,4):
│0 1 0 0│
│1 0 1 1│
m.sub(5,5,3,3):
│0 0 0│
│1 0 1│
│0 0 1│

See Also