Swap two rows in a numpy array in python [duplicate]

Put the index as a whole:

a[[x, y]] = a[[y, x]]

With your example:

a = np.array([[4,3,1], [5,7,0], [9,9,3], [8,2,4]])

a 
# array([[4, 3, 1],
#        [5, 7, 0],
#        [9, 9, 3],
#        [8, 2, 4]])

a[[0, 2]] = a[[2, 0]]
a
# array([[9, 9, 3],
#       [5, 7, 0],
#       [4, 3, 1],
#       [8, 2, 4]])