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I'm fairly new with numpy.

As shown below, when I try to cast the numeric values from strings to integers, it doesn't seem to 'stick', as below:

>> import numpy as np >>> a = np.array([['a','1','2'],['b','3','4']]) >>> a[:,1:3].astype(int) array([[1, 2], [3, 4]]) >>> a[:,1:3] = a[:,1:3].astype(int) >>> a array([['a', '1', '2'], ['b', '3', '4']], dtype='<U1')

How can I convert the string values to ints in the array ?

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    NumPy arrays are homogeneous, there are no mixed type arrays (except object arrays but these are not what I would call recommended!). So the question you need to ask yourself is: what integer value should 'a' or 'b' have? Commented Jul 16, 2017 at 9:21

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You need to first change the dtype of the full array to object in order for it to contain both strings and integers:

a = a.astype(object) a[:,1:3] = a[:,1:3].astype(int) print(a) > [['a' 1 2] ['b' 3 4]]

Though note that better solutions may exist, for example using pandas, using columns of different types.

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