python - Length of each string in a NumPy array

Question

Is there any builtin operation in NumPy that returns the length of each string in an array?

I don't think any of the NumPy string operations does that, is this correct?

I can do it with a for loop, but maybe there's something more efficient?

import numpy as np
arr = np.array(['Hello', 'foo', 'and', 'whatsoever'], dtype='S256')

sizes = []
for i in arr:
    sizes.append(len(i))

print(sizes)
[5, 3, 3, 10]

Answer 1

You can use vectorize of numpy. It is much faster.

mylen = np.vectorize(len)
print mylen(arr)