Removing non numeric characters from a string

Question

I have been given the task to remove all non numeric characters including spaces from a either text file or string and then print the new result next to the old characters for example:

Before:

sd67637 8

After:

As i am a beginner i do not know where to start with this task. Please Help

Possible duplicate of [Remove characters except digits from string using Python?](https://stackoverflow.com/q/1450897/608639) — jww, Jun 30 '19 at 13:13

score 92 · Accepted Answer · answered Jun 27 '13 at 07:52

92

The easiest way is with a regexp

import re
a = 'lkdfhisoe78347834 (())&/&745  '
result = re.sub('[^0-9]','', a)

print result
>>> '78347834745'

answered Jun 27 '13 at 07:52

mar mar

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any way to leave decimals in? – Mark Jul 19 '17 at 20:54
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Why not `[^\d]+`? – scry May 25 '19 at 23:36

score 24 · Answer 2 · edited Jun 27 '13 at 07:49

24

Loop over your string, char by char and only include digits:

new_string = ''.join(ch for ch in your_string if ch.isdigit())

Or use a regex on your string (if at some point you wanted to treat non-contiguous groups separately)...

import re
s = 'sd67637 8' 
new_string = ''.join(re.findall(r'\d+', s))
# 676378

Then just print them out:

print(old_string, '=', new_string)

edited Jun 27 '13 at 07:49

jamylak

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answered Jun 27 '13 at 07:20

Jon Clements

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This is nicer because it doesn't just apply to ascii – jamylak Jun 27 '13 at 07:50

score 10 · Answer 3 · edited Jun 20 '20 at 09:12

10

There is a builtin for this.

string.translate(s, table[, deletechars])

Delete all characters from s that are in deletechars (if present), and then translate the characters using table, which must be a 256-character string giving the translation for each character value, indexed by its ordinal. If table is None, then only the character deletion step is performed.

>>> import string
>>> non_numeric_chars = ''.join(set(string.printable) - set(string.digits))
>>> non_numeric_chars = string.printable[10:]  # more effective method. (choose one)
'sd67637 8'.translate(None, non_numeric_chars)
'676378'

Or you could do it with no imports (but there is no reason for this):

>>> chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c'
>>> 'sd67637 8'.translate(None, chars)
'676378'

edited Jun 20 '20 at 09:12

Community

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answered Jun 27 '13 at 07:36

Inbar Rose

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This should be the top answer. – akhan Jan 11 '17 at 07:44
Not really `>>> 's.,d67637 8'.translate(None, 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ ')` yields `'.,676378'` – Darth Kotik Jan 11 '17 at 08:47
@DarthKotik good point, OP didn't mentioned anything about special characters, but that is easy to solve. Check my edit. – Inbar Rose Jan 11 '17 at 08:57
@InbarRose it'll work but as soon as you wan to use some cyrillic symbol or something Chinese it'll fail. This solution is good as far as you know exactly what set of symbols might present in your field which is not really good. – Darth Kotik Jan 11 '17 at 09:05
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@DarthKotik OP had no mention of special characters or encoding. Regardless, string.translate can solve all of those problems with the correct input. Much like every problem, it should be solved one step at a time. And in Agile development there is no need for premature optimization. The question was simple, the answer is simple. If you want to get into minutia we will be here all day. – Inbar Rose Jan 11 '17 at 09:39
Not Python 3 compatible. Very outdated answer. – Elia Iliashenko Aug 29 '18 at 11:34
@InbarRose Please update answer for python 3 (https://stackoverflow.com/a/41708804/828885) – akhan Mar 04 '19 at 17:55

Saullo G. P. Castro · Answer 4 · 2019-07-24T10:54:20.760

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You can use string.ascii_letters to identify your non-digits:

from string import *

a = 'sd67637 8'
a = a.replace(' ', '')

for i in ascii_letters:
    a = a.replace(i, '')

In case you want to replace a colon, use quotes " instead of colons '.

edited Jul 24 '19 at 10:54

answered Jun 27 '13 at 07:28

Saullo G. P. Castro

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What about a colon? – jtlz2 Jul 24 '19 at 10:46
@jtlz2 then you use `a = a.replace("'", "")`, note the colon within quotes – Saullo G. P. Castro Jul 24 '19 at 10:53
' is not a colon, it's a single quote. : is a colon. And this answer only replaces [a-z] (ignoring case). And finally, why import * from string if you are only using ascii_letters? – tbm Jun 08 '20 at 15:22

Removing non numeric characters from a string

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