cond1 = (my_array[:, (0)] > 4) & (my_array[:, (0)] < 13)
cond2 = (my_array[:, (1)] > 3) & (my_array[:, (1)] < 5)
cond3 = (my_array[:, (2)] > 6) & (my_array[:, (2)] < 10)
extracting specific rows of Nx3 array whereby each column satisfies condition