Change String to Float Python

Question

I would like to convert a list that I took out from a txt file into a float so I can make some calculous after in Python. I have the following list:

['1,0,1.2', '2,-1.5,1.2', '3,-1.5,0', '4,0,0', '5,1.5,1.2']

And I would like it to look like this:

[1,0,1.2,2,-1.5,1.2,3,-1.5,0,4,0,0,5,1.5,1.2]

All of them being float type.

Thank you in advance

You have to iterate over the strings in the list, split each string by the commas and convert each number-string to a float. If you have a specific issue while solving this yourself you can ask here with your code. — Michael Butscher
– Michael Butscher, Commented Oct 18, 2022 at 21:44
that looks like CSV, maybe you should be using the csv module, or maybe pandas to read it in — Sam Mason
– Sam Mason, Commented Oct 19, 2022 at 13:06

Daraan · Accepted Answer · 2022-10-19 11:24:21Z

1

Two loops are needed here, an outer for the array and an inner loop over the spitted strings.

>>> new = [float(v) for inner in a for v in inner.split(",")]
>>> new
[1.0, 0.0, 1.2, 2.0, -1.5, 1.2, 3.0, -1.5, 0.0, 4.0, 0.0, 0.0, 5.0, 1.5, 1.2]

EDIT: To up it to accept any case, differentiate between int/float for example:

    >>> from ast import literal_eval
    >>> new = [literal_eval(v) for inner in a for v in inner.split(",")]
    >>> new
    [1, 0, 1.2, 2, -1.5, 1.2, 3, -1.5, 0, 4, 0, 0, 5, 1.5, 1.2]

edited Oct 19, 2022 at 11:24

answered Oct 18, 2022 at 21:48

Daraan

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2 Comments

Mark Ransom Over a year ago

To be completely true to the OPs example, you'd need a replacement for float(v) that returns float if the string contains a decimal point and int if it doesn't.

Mark Ransom Over a year ago

Thanks for responding to my comment with the edit. That's a nice solution.

Rahul K P · Accepted Answer · 2022-10-18 22:01:32Z

0

You can do with map,

In [1]: l = ['1,0,1.2', '2,-1.5,1.2', '3,-1.5,0', '4,0,0', '5,1.5,1.2']

In [2]: list(map(float, ','.join(l).split(',')))
Out[2]: [1.0, 0.0, 1.2, 2.0, -1.5, 1.2, 3.0, -1.5, 0.0, 4.0, 0.0, 0.0, 5.0, 1.5, 1.2]

edited Oct 18, 2022 at 22:01

answered Oct 18, 2022 at 21:45

Rahul K P

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2 Comments

Mark Ransom Over a year ago

Did you even check your results?

Rahul K P Over a year ago

@MarkRansom Yeah, Just missed out , in join. Thanks for pointing that out. Updated.

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