A Neater Way To Set Values At Indexes With Numpy

I have a numpy array initially with zeros, like this: v = np.zeros((5, 5)) v array([[ 0., 0., 0., 0., 0.], [ 0., 0., 0., 0., 0.], [ 0., 0., 0., 0., 0.],

Solution 1:

In search of a more "compact" way of expressing it, I got this -

v = np.zeros((5, 5))
v[tuple(np.r_[idx1,idx1[:,::-1]].T)] = 1v[tuple(np.r_[idx2,idx2[:,::-1]].T)] = 0

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On python3.6+, you can use the * unpacking operator to reduce this further:

v[[*np.r_[idx1,idx1[:,::-1]].T]] = 1
v[[*np.r_[idx2,idx2[:,::-1]].T]] = 0
v

array([[ 0.,  0.,  0.,  1.,  0.],
       [ 0.,  0.,  0.,  0.,  0.],
       [ 0.,  0.,  0.,  0.,  1.],
       [ 1.,  0.,  0.,  0.,  0.],
       [ 0.,  0.,  1.,  0.,  0.]])