convert string representation of array to numpy array in python

Question

I can convert a string representation of a list to a list with ast.literal_eval. Is there an equivalent for a numpy array?

x = arange(4)
xs = str(x)
xs
'[0 1 2 3]'
# how do I convert xs back to an array

Using ast.literal_eval(xs) raises a SyntaxError. I can do the string parsing if I need to, but I thought there might be a better solution.

Answer 1

For 1D arrays, Numpy has a function called fromstring, so it can be done very efficiently without extra libraries.

Briefly you can parse your string like this:

s = '[0 1 2 3]'
a = np.fromstring(s[1:-1], dtype=np.int, sep=' ')
print(a) # [0 1 2 3]

For nD arrays, one can use .replace() to remove the brackets and .reshape() to reshape to desired shape, or use Merlin's solution.

Answer 2

Try this:

xs = '[0 1 2 3]'

import re, ast
ls = re.sub('\s+', ',', xs)
a = np.array(ast.literal_eval(ls))
a  # -> array([0, 1, 2, 3])