Create a numpy array according to another array along with indices array

Question

I have a numpy array(eg., a = np.array([ 8., 2.])), and another array which stores the indices I would like to get from the former array. (eg., b = np.array([ 0., 1., 1., 0., 0.]).

What I would like to do is to create another array from these 2 arrays, in this case, it should be: array([ 8., 2., 2., 8., 8.])

of course, I can always use a for loop to achieve this goal:

for i in range(5):
    c[i] = a[b[i]]

I wonder if there is a more elegant method to create this array. Something like c = a[b[0:5]] (well, this apparently doesn't work)

Frank M · Accepted Answer · 2015-12-10 03:11:20Z

2

Only integer arrays can be used for indexing, and you've created b as a float64 array. You can get what you're looking for if you explicitly convert to integer:

bi = np.array(b, dtype=int)
c = a[bi[0:5]]

answered Dec 10, 2015 at 3:11

Frank M

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