Convert an array stored as a string, to a proper numpy array

Question

For long and tedious reasons, I have lots of arrays that are stored as strings:

tmp = '[[1.0, 3.0, 0.4]\n [3.0, 4.0, -1.0]\n [3.0, 4.0, 0.1]\n [3.0, 4.0, 0.2]]'

Now I obviously do not want my arrays as long strings, I want them as proper numpy arrays so I can use them. Consequently, what is a good way to convert the above to:

tmp_np = np.array([[1.0, 3.0, 0.4]
                   [3.0, 4.0, -1.0]
                   [3.0, 4.0, 0.1]
                   [3.0, 4.0, 0.2]])

such that I can do simple things like tmp_np.shape = (4,3) or simple indexing tmp_np[0,:] = [1.0, 3.0, 0.4] etc.

Thanks

Have you seen stackoverflow.com/questions/20200353/… and a lot of other documentations regard this problem in Internet? — Kasravnd
– Kasravnd, Commented Jun 7, 2018 at 13:56

sacuL · Accepted Answer · 2018-06-07 14:05:02Z

1

You can use ast.literal_eval, if you replace your \n characters with ,:

temp_np = np.array(ast.literal_eval(tmp.replace('\n', ',')))

Returns:

>>> tmp_np
array([[ 1. ,  3. ,  0.4],
       [ 3. ,  4. , -1. ],
       [ 3. ,  4. ,  0.1],
       [ 3. ,  4. ,  0.2]])

answered Jun 7, 2018 at 14:05

sacuL

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