Get a forward operator as a sparse matrix in astra toolbox

gistfile1.txt

import numpy as np
import matplotlib.pyplot as plt
import astra

if 0:
    data_corr = np.load('tomo_corr.npy')
    vecs = np.load('vectors.npy')
else:
    import scipy.io
    data_mat = scipy.io.loadmat('../data/Fewer_Plastics_tomo_corr_low_high_vectors')
    data_corr = data_mat['tomo_corr']
    vecs = data_mat['vectors']

#omo_corr=data_corr[:,210:438,:]
detpixels = data_corr.shape[1]
height = detpixels
width = detpixels

angle_idx = np.arange(0, 360, 1)
#angle_idx=np.linspace(0, 359, data_corr.shape[0],endpoint=False, dtype=int)

vecs = vecs[angle_idx, :]

proj_geom = astra.create_proj_geom('fanflat_vec', detpixels, vecs)
vol_geom = astra.create_vol_geom(width)
proj_id = astra.create_projector('line_fanflat', proj_geom, vol_geom);

mat_id = astra.projector.matrix(proj_id)
A_forward = astra.matrix.get(mat_id)

from scipy.sparse import csr_matrix, bmat
A_coo = csr_matrix(A_forward)
A = bmat([[A_coo, None], [None, A_coo]])