Strip Numbers From String in Python

Question

Is there an efficient way to strip out numbers from a string in python? Using nltk or base python?

Thanks, Ben

if I have a string let's say for example: x = "I have 3 dogs" I'd want a way to turn x into: "I have dogs" — ben890, May 19 '15 at 00:51
Or.... "It's the 1st road on your left, then take the 2nd road on the right, then the company you're after is called TRG1 it's about 100m up the road - if you're lazy - you can catch a bus for £2.50" ? — Jon Clements, May 19 '15 at 00:56
Check out other good answers here: https://stackoverflow.com/questions/12851791/removing-numbers-from-string — tommy.carstensen, Dec 19 '19 at 22:07

Martin Konecny · Accepted Answer · 2016-12-22T17:10:46.413

37

Yes, you can use a regular expression for this:

import re
output = re.sub(r'\d+', '', '123hello 456world')
print output  # 'hello world'

edited Dec 22 '16 at 17:10

answered May 19 '15 at 00:51

Martin Konecny

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This is perfect! Thanks Martin – ben890 May 19 '15 at 00:52
Can't go wrong with the regex solution, since it also translate very well to other instances (say he wants to remove letters next). – Alex Huszagh May 19 '15 at 00:57
The best answer. Works like charm – Kareem Khaleel Aug 31 '21 at 11:19

Robᵩ · Answer 2 · 2015-05-19T00:58:52.500

15

str.translate should be efficient.

In [7]: 'hello467'.translate(None, '0123456789')
Out[7]: 'hello'

To compare str.translate against re.sub:

In [13]: %%timeit r=re.compile(r'\d')
output = r.sub('', my_str)
   ....: 
100000 loops, best of 3: 5.46 µs per loop

In [16]: %%timeit pass
output = my_str.translate(None, '0123456789')
   ....: 
1000000 loops, best of 3: 713 ns per loop

edited May 19 '15 at 00:58

answered May 19 '15 at 00:53

Robᵩ

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The problem is: `str.translate` is a bit difficult to make both 2.x/3.x compatible :( – Jon Clements May 19 '15 at 01:02
7

So you'd need `my_str.translate({ord(ch): None for ch in '0123456789'})` in 3.x – Jon Clements May 19 '15 at 01:05
I wonder how long r.sub() takes? Say, under conditions where you want to do this over multiple strings and you've pre-compiled the regex. – Ross May 19 '15 at 01:26
@Ross - Judging from the code I put in my answer, 5.46µs. – Robᵩ May 19 '15 at 01:28
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@Rob - Ah right, I missed that the first line is the set up line. Looking at some best/worst cases translate seems to perform much better at worst case scenarios. Using 'python -m timeit' I came across the following in favour of translate; `'123hello 456world' - x5.0` `'1234567890987654321012345678909876543210' - x17.0` `'5a$%&^@)9lhk45g08j%Gmj3g09jSDGjg0034k' - x9.0` `'hello world im your boss' - x 1.8` – Ross May 19 '15 at 01:48

Deacon · Answer 3 · 2015-05-19T14:00:17.303

Here's a method using str.join(), str.isnumeric(), and a generator expression which will work in 3.x:

>>> my_str = '123Hello, World!4567'
>>> output = ''.join(c for c in my_str if not c.isnumeric())
>>> print(output)
Hello, World!
>>>

This will also work in 2.x, if you use a unicode string:

>>> my_str = u'123Hello, World!4567'
>>> output = ''.join(c for c in my_str if not c.isnumeric())
>>> print(output)
Hello, World!
>>>

Hmm. Throw in a paperclip and we'd have an episode of MacGyver.

Update

I know that this has been closed out as a duplicate, but here's a method that works for both Python 2 and Python 3:

>>> my_str = '123Hello, World!4567'
>>> output = ''.join(map(lambda c: '' if c in '0123456789' else c, my_str))
>>> print(output)
Hello, World!
>>>

Strip Numbers From String in Python

3 Answers3

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