Python subtract first element from each respective row of matrix
Question: I want to subtract the first value of a row from the rest of the elements of
that row, so for

    
    
    import numpy as np
    
    z = np.array([[1,2,3,4],[4,5,6,7],[7,8,9,9]])
    
    for n in range(0,3):
        znew = z[n,:]-z[n,0]
    

`znew` should be `np.array([[0,1,2,3],[0,1,2,3],[0,1,2,2]])`. How can I do
this? It kind of seems trivial.


Answer: You can do this by taking advantage of broadcasting:

    
    
    >>> z - z[:,0][:, None] # or z - z[:,0][:, np.newaxis]
    array([[0, 1, 2, 3],
           [0, 1, 2, 3],
           [0, 1, 2, 2]])
    

