Convert Numpy array of ASCII codes to string

Question

I would like to convert a NumPy array of integers representing ASCII codes to the corresponding string. For example ASCII code 97 is equal to character "a". I tried:

from numpy import *
a=array([97, 98, 99])
c = a.astype('string')
print c

which gives:

['9' '9' '9']

but I would like to get the string "abc".

Answer 1

import numpy as np
np.array([97, 98, 99], dtype='b').tobytes().decode("ascii")

Output:

'abc'

Data type objects (dtype)

tostring() is deprecated since version 1.19.0. Use tobytes() instead.

Answer 2

Another solution that does not involve leaving the NumPy world is to view the data as strings:

arr = np.array([97, 98, 99], dtype=np.uint8).view('S3').squeeze()

or if your numpy array is not 8-bit integers:

arr = np.array([97, 98, 99]).astype(np.uint8).view('S3').squeeze()

In these cases however you do have to append the right length to the data type (e.g. 'S3' for 3 character strings).

Answer 3

print "".join([chr(item) for item in a])

output

abc