python regex - extracting digits from string with numbers and characters

Question

I have data that has strings like 'ms2p5', 'ms3', 'ms10' for which I need to extract the digits as convert to numbers as follows.

'ms2p5' => 2.5
'ms3' => 3
'ms10' => 10

I tried the below regex and it is able to get the match. One issue is with values having a character in the middle of the extracted string like '2p5'. What is the right approach to have a generic function that handles all these cases well while converting them into numeric values?

import re
re.search(r'\d+[p]*\d*', str).group()

What's wrong with the regex you currently have?

Nick
– Nick

2020-01-21 03:58:35 +00:00
Commented Jan 21, 2020 at 3:58 — Nick
– Nick, Commented Jan 21, 2020 at 3:58
What about ".".join(re.findall(r'\d+', string))?

Henry Yik
– Henry Yik

2020-01-21 04:02:39 +00:00
Commented Jan 21, 2020 at 4:02 — Henry Yik
– Henry Yik, Commented Jan 21, 2020 at 4:02

U13-Forward · Accepted Answer · 2020-01-21 04:04:35Z

2

Use str.join with re.findall:

los = ['ms2p5', 'ms3', 'ms10']
print([float('.'.join(re.findall('\d+', i))) for i in los])

Output:

[2.5, 3.0, 10.0]

answered Jan 21, 2020 at 4:04

U13-Forward

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Comments

Nick · Accepted Answer · 2020-01-21 04:09:40Z

2

You could write an extraction function that searched for a numeric value (with or without p for a decimal point, replaced the p with a . and then converted to float. For example:

import re

def extract_num(s):
    return float(re.search(r'\d+p?\d*', s).group().replace('p', '.'))

strs = ['ms2p5', 'ms3', 'ms10']
print([extract_num(s) for s in strs])

Output:

[2.5, 3.0, 10.0]

edited Jan 21, 2020 at 4:09

answered Jan 21, 2020 at 4:04

Nick

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Comments

Haleemur Ali · Accepted Answer · 2020-01-21 04:09:52Z

1

If the strings all follow the examples you provide, I'd probably just do:

x = 'ms2p5'
float(x[2:].replace('p', '.'))

answered Jan 21, 2020 at 4:09

Haleemur Ali

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