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I have a string which is [-0.0597212 0.00344087 -0.23413301 0.02406648]

As you see, there is [ at first, there are 3 spaces between 1st and 2nd value, 1 space between 2nd and 3rd value, 2 spaces between 3rd and 4th value, and there is ] at the end.

I want to decompose these 4 numerical values with their signs and I will assign these 4 values to an 4-element array.

For example;

a[0]=-0.0597212
a[1]=0.00344087
a[2]=-0.23413301
a[3]=0.02406648

Normally there will be 128 elements with like this text (there will be maximum 3 spaces, minimum 1 space between values), but I want to try to find the solution with this example. I tried split.strip() and replace() functions but I didn't find any solution for me. Can you help me ?

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  • 2
    Is there a reason why you're working with a string representation of a numpy array, rather than an actual numpy array? Commented Mar 10, 2019 at 10:34

3 Answers 3

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a="[-0.0597212   0.00344087 -0.23413301  0.02406648]"

#split string
a = a.split() 

#delete open & close square bracket
a[0] =  a[0][1:] 
a[-1] = a[-1][:-1] 

#convert to float
for i in range(len(a)):
    a[i] = float(a[i])
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4 Comments

so much thanks, I tried with 128 elements and it worked !! but the only bug is, if it ends like "0.0192611 ]" (1 space before "]" ), it shows whole numbers but with an error "ValueError: could not convert string to float:", so do you have a solution for this?
Welcome dude :D For that case you can just add this code before convert to float: if a[-1]=='': a.pop(-1)
special thanks for answer dude, it works perfectly :) but I wondered the logic on a[0] and a[-1] line. Can you briefly explain this?
given variable a is list on python, a[0] mean the first value of list and a[-1] mean last value of the list, that's how Python work. a[0] = a[0][1:] changing the value of a[0] with substring of previous value from index 1 until last index (a[0] still a string and Python start index from 0). You can learn more (or maybe just find what you need) on this book: souravsengupta.com/cds2015/python/LPTHW.pdf
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list(map(float, txt[1:-1].split()))
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5 Comments

This just assumes that the first and last character should be removed, what if there is something around them, e.g. ` [ 1 2 3 ] `?
@zvone I made the liberty of making the assumption based on the question asked. It is very specifically mentioned about the first and last characters in the string.
thank you mujjiga but I didn't understand how can I print the whole elements of array?
You mean a = list(map(float, txt[1:-1].split())); print (a)
also if you have spaces around [ and ] you can use a = list(map(float, txt.strip()[1:-1].split()));print (a)
1

If you use numpy():

import numpy as np

s = '[-0.0597212   0.00344087 -0.23413301  0.02406648]'

np.fromstring(s.strip('[]'), dtype=float, sep=' ')
# [-0.0597212   0.00344087 -0.23413301  0.02406648]

You can also use ast.literal_eval:

import ast
import re

ast.literal_eval(re.sub(r'\s+', ',', s))
# [-0.0597212, 0.00344087, -0.23413301, 0.02406648]
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1 Comment

thank you Mykola Zotko but I didn't understand how can I print the whole elements of array?

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