Convert a string to a list of floats (in python)

Question

For data storage purposes I am trying to recover lists of floats from a .txt file. From the string like:

a = '[1.3, 2.3, 4.5]'

I want to recover:

a = [1.3, 2.3, 4.5]

I was expecting a simple solution like list(a), but I cannot find anything like that.

Possible duplicate of [Convert string representation of list to list](https://stackoverflow.com/questions/1894269/convert-string-representation-of-list-to-list) — Ishara Madhawa, May 15 '18 at 11:50

score 3 · Answer 1 · answered May 15 '18 at 11:49

3

Use the ast module.

Ex

import ast
print(ast.literal_eval('[1.3, 2.3, 4.5]'))

Output:

[1.3, 2.3, 4.5]

answered May 15 '18 at 11:49

Rakesh

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Rakesh, bro, do we really need to answer this one? :) (Not the downvoter) – heemayl May 15 '18 at 11:50

score 2 · Answer 2 · answered May 15 '18 at 11:51

2

You can also use a more manual way:

[eval(x) for x in '[1.3, 2.3, 4.5]'.strip("[").strip("]").split(",")]
Out[64]: [1.3, 2.3, 4.5]

answered May 15 '18 at 11:51

Mathieu

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score 2 · Answer 3 · answered May 15 '18 at 11:52

2

You could use json

import json
a = '[1.3, 2.3, 4.5]'
json.loads(a)

answered May 15 '18 at 11:52

Adson Leal

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score 0 · Answer 4 · answered May 15 '18 at 11:54

0

well if you are sure that your input data is of type, a = '[1.3, 2.3, 4.5]' then you could use the eval command and assign it to same or a different variable.

a = '[1.3, 2.3, 4.5]'
b=eval(a)
print(b.__class__)  # to know if b is of type list or not

answered May 15 '18 at 11:54

Surya Tej

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score 0 · Answer 5 · answered May 15 '18 at 11:54

0

a = a.split(",")
a[0] = a[0][1:]
a[-1] = a[-1][:-1]
a = [float(i) for i in a]

This should work :)

answered May 15 '18 at 11:54

Tanay Agrawal

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Convert a string to a list of floats (in python)

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