@decorator_util.jit()<EOL>def mapping_matrix_from_sub_to_pix(sub_to_pix, pixels, regular_pixels, sub_to_regular, sub_grid_fraction):
mapping_matrix = np.zeros((regular_pixels, pixels))<EOL>for sub_index in range(sub_to_regular.shape[<NUM_LIT:0>]):<EOL><INDENT>mapping_matrix[sub_to_regular[sub_index], sub_to_pix[sub_index]] += sub_grid_fraction<EOL><DEDENT>return mapping_matrix<EOL>
Computes the mapping matrix, by iterating over the known mappings between the sub-grid and pixelization.

    Parameters
    -----------
    sub_to_pix : ndarray
        The mappings between the observed regular's sub-pixels and pixelization's pixels.
    pixels : int
        The number of pixels in the pixelization.
    regular_pixels : int
        The number of datas pixels in the observed datas and thus on the regular grid.
    sub_to_regular : ndarray
        The mappings between the observed regular's sub-pixels and observed regular's pixels.
    sub_grid_fraction : float
        The fractional area each sub-pixel takes up in an regular-pixel.