How do I create a numpy array from string?

Question

I have a file reader that reads n bytes from a file and returns a string of chars representing that (binary) data. I want to read up n bytes into a numpy array

Answer 1

You can do this directly with numpy.fromstring:

import numpy as np
s = '\x01\x05\x03\xff'
a = np.fromstring(s, dtype='uint8')

Once completing this, a is array([ 1, 5, 3, 255]) and you can use the regular scipy/numpy FFT routines.

Answer 2

>>> '\x01\x05\x03\xff'
'\x01\x05\x03\xff'
>>> map(ord, '\x01\x05\x03\xff')
[1, 5, 3, 255]
>>> numpy.array(map(ord, '\x01\x05\x03\xff'))
array([  1,   5,   3, 255])

Answer 3

Without knowing what you've got coming in it's tough, but if it were comma delimited integers you could do something like this:

myInts = map(int, myString.split(','))