Python String Parsing Floats

Question

How to change a '14/15' string to a float? I am trying to extract data from a text file would like to convert '1/3' to a float. float('1/3') doesn't work. I was thinking about splitting into two parts at '/' by 1 and 3 then dividing, but it seems cludgy. Is there a more pythonic way to do this? I'm using Python 2.7

Do you only need to parse `X/Y`, or are you looking for a more general expression evaluator? — NPE, Oct 07 '14 at 21:06

score 2 · Answer 1 · edited May 23 '17 at 12:20

2

If you only ever need to evaluate simple X/Y fractions:

s = "14/15"
num, denom = map(float, s.split("/", 1))
print(num / denom)

If you need a more complete expression evaluator, take a look at the asteval module.

Using eval() might also see like a nice easy way to do it, but I'd advise against it for security reasons.

edited May 23 '17 at 12:20

Community

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answered Oct 07 '14 at 21:08

NPE

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score 0 · Accepted Answer · answered Oct 07 '14 at 21:06

0

If you trust your input:

from __future__ import division

eval('14/15')

answered Oct 07 '14 at 21:06

nullstellensatz

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Simple and elegant. Thanks, @nullstellensatz. – RaymondMachira Oct 07 '14 at 21:21
Also, really dangerous if you don't know where your data came from. – Ned Batchelder Oct 08 '14 at 14:34

Python String Parsing Floats

2 Answers2