Python: how can I identify a decimal number in a string?

Question

How can I identify decimal numbers in a list of strings, in order to remove them? Ideally in a single operation, something like content = [x for x in content if not x.isdecimal()]

(Sadly, isdecimal() and isnumeric() don't work here)

For instance, if content = ['55', 'line', '0.04', 'show', 'IR', '50.5', 'find', 'among', '0.06', 'also', 'detected', '0.05', 'ratio', 'fashion.sense', '123442b'] I would like the output to be content = ['line', 'show', 'IR', 'find', 'among', 'also', 'detected', 'ratio', 'fashion.sense', '123442b']

So what are you trying to achieve? Filter strings in a list that contain a decimal point? Keep those, discard those? Please do include inputs and expected outputs. — Martijn Pieters, Sep 23 '17 at 16:05
Please do include a sample list and the expected output. Try to think of edgecases (whitespace? thousands-separators?). Think the problem through. — Martijn Pieters, Sep 23 '17 at 16:08
Thanks. There should not be whitespace. Thousands-separators... maybe but I don't mind if they slip through. — Unstack, Sep 23 '17 at 16:15
Yes, integers too, if possible. Otherwise I can remove those in a separate operation (with isdecimal/isnumeric). — Unstack, Sep 23 '17 at 16:22

DjaouadNM · Accepted Answer · 2017-09-24T02:08:51.360

3

You should use a regex to test if a string is a decimal:

import re
content = ['line', '0.04', 'show', 'IR', '50.5', 'find', 'among', '0.06', 'also', 'detected', '0.05', 'ratio', 'fashion.sense', '123442b']
regex = r'^[+-]{0,1}((\d*\.)|\d*)\d+$'
content = [x for x in content if re.match(regex, x) is None]
print(content)
# => ['line', 'show', 'IR', 'find', 'among', 'also', 'detected', 'ratio', 'fashion.sense', '123442b']

edited Sep 24 '17 at 02:08

answered Sep 23 '17 at 16:07

DjaouadNM

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That's very good, but it lets single-digit numbers slip through. – Unstack Sep 23 '17 at 16:38
@Unstack You want to keep integers, don't you? single digit numbers are integers, so they are in the result list. – DjaouadNM Sep 23 '17 at 16:39
@Unstack Anyways, I edited my answer, it should now remove integers as well. – DjaouadNM Sep 23 '17 at 16:44

score 0 · Answer 2 · answered Sep 23 '17 at 21:24

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Just adding to Mr Geek answer, You should also check out the python's docs on Regex.

answered Sep 23 '17 at 21:24

Jermaine

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this should be a comment then not an answer! – Zahra Nov 01 '17 at 17:32
Thanks for your correction, just realised what I did. – Jermaine Nov 04 '17 at 03:53

Python: how can I identify a decimal number in a string?

2 Answers2