python - Numpy: Replace random elements in an array -

i googled bit , didn't find answers.

the thing is, have 2d numpy array , i'd replace of values @ random positions.

i found answers using numpy.random.choice create mask array. unfortunately not create view on original array can not replace values.

so here example of i'd do.

imagine have 2d array float values.

[[ 1., 2., 3.],  [ 4., 5., 6.],  [ 7., 8., 9.]] 

and i'd replace arbitrary amount of elements. nice if tune parameter how many elements going replaced. possible result this:

[[ 3.234, 2., 3.],  [ 4., 5., 6.],  [ 7., 8., 2.234]] 

i couldn't think of nice way accomplish this. appreciated.

edit

thanks quick replies.

just mask input array random 1 of same shape.

import numpy np  # input array x = np.array([[ 1., 2., 3.], [ 4., 5., 6.], [ 7., 8., 9.]])  # random boolean mask values changed mask = np.random.randint(0,2,size=x.shape).astype(np.bool)  # random matrix same shape of data r = np.random.rand(*x.shape)*np.max(x)  # use mask replace values in input array x[mask] = r[mask] 

produces this:

[[ 1.          2.          3.        ]  [ 4.          5.          8.54749399]  [ 7.57749917  8.          4.22590641]]