Hi doing some stuff over a network and wondering if there is any way of converting python array as a string back into a python array.. for example
x = "[1,2,3,4]"
converting x to
x_array = [1,2,3,4]
Bonus if it can also work for numpy multidimensional arrays!
For the normal arrays, use ast.literal_eval:
>>> from ast import literal_eval
>>> x = "[1,2,3,4]"
>>> literal_eval(x)
[1, 2, 3, 4]
>>> type(literal_eval(x))
<type 'list'>
>>>
numpy.array's though are a little tricky because of how Python renders them as strings:
>>> import numpy as np
>>> x = [[1,2,3], [4,5,6]]
>>> x = np.array(x)
>>> x
array([[1, 2, 3],
[4, 5, 6]])
>>> x = str(x)
>>> x
'[[1 2 3]\n [4 5 6]]'
>>>
One hack you could use though for simple ones is replacing the whitespace with commas using re.sub:
>>> import re
>>> x = re.sub("\s+", ",", x)
>>> x
'[[1,2,3],[4,5,6]]'
>>>
Then, you can use ast.literal_eval and turn it back into a numpy.array:
>>> x = literal_eval(x)
>>> np.array(x)
array([[1, 2, 3],
[4, 5, 6]])
>>>
Python 2.7.5+ (default, Sep 19 2013, 13:48:49)
>>> import json
>>> json.loads("[1,2,3,4]")
[1, 2, 3, 4]
>>>
I would suggest that you don't actually want to do this. This kind of thing isn't going to be scalable easily to sending, for instance, instances of classes you've defined across a network. Instead, I would suggest that you use something like pickle or json to convert the data to bytes, send it across the network, and then convert the data back. However, in other situations I would always use ast.literal_eval. If you specify how you are sending the data across the network, I'll give you example usage of pickle for your situation.
Try this:
x_array = [(int(y) if y.strip() else None) for y in x[1:-1].split(',')]
list(filter(lamda x: x is not None, around this to strip the None values.If you're sure the strings are always going to have that structure, you could remove the brackets and split the string:
x_array = [int(y) for y in x[1:-1].split(',') if y.strip()]
x = "[1, 2, 3, 4, 5, ]".