regular expression get number from string

Question

First I am using python 2.7

I have these possibilities of the string:

3 paths

12  paths

12 path rooms

Question

what is the reqular expression to get the number without the text.

thanks

Why not just split on the space? Or - do you have other examples that means that's not viable... — Jon Clements
– Jon Clements, Commented Mar 6, 2014 at 18:14
@JonClements since I am using scrapy, i am allowed to use just xpath and reqular expression, i can't use python functions — Marco Dinatsoli
– Marco Dinatsoli, Commented Mar 6, 2014 at 18:15
errr no... once you've extracted the string, there's nothing to stop you using builtin str operations — Jon Clements
– Jon Clements, Commented Mar 6, 2014 at 18:16
@JonClements I do know that :). I mean that in the policy of where I am working I can't use python functions — Marco Dinatsoli
– Marco Dinatsoli, Commented Mar 6, 2014 at 18:19
okay... I've put the scrapy tag back - you might want to edit your question to include these comments and the fact that this is not a standalone regular expression with standalone strings... — Jon Clements
– Jon Clements, Commented Mar 6, 2014 at 18:20

Jon Clements · Accepted Answer · 2014-03-06 18:21:53Z

2

You say you can only use scrapy methods, so I guess you're after:

hxs.select('//some/xpath/expression/text()').re(r'(\d+).*')

answered Mar 6, 2014 at 18:21

Jon Clements

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ifryed · Accepted Answer · 2014-03-06 18:15:12Z

2

you can use this: Regex = [\d]*

answered Mar 6, 2014 at 18:15

ifryed

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Selcuk · Accepted Answer · 2014-03-06 18:19:10Z

2

An alternative way would be to use [0-9] instead of \d

import re

def extract_number(string):
    r = re.compile('[0-9]+')
    return r.match(string).group()

answered Mar 6, 2014 at 18:19

Selcuk

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limasxgoesto0 · Accepted Answer · 2014-03-06 18:16:38Z

1

(\d+).*\n for pulling the numbers and then skipping the rest of the line.

number_finder = re.compile('(\d+).*\n') number_finder.findall(mystr)

will output an array of the number values

Example:

In [3]: r = re.compile('(\d+).*\n') In [4]: r.findall('12 a \n 12 a \n') Out[4]: ['12', '12']

answered Mar 6, 2014 at 18:16

limasxgoesto0

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1 Comment

vicd Over a year ago

cross multiple-line search, just use re.M flag, it codes like re.findall(r'\d+',multiple_line_string,re.M) :-)

shaktimaan · Accepted Answer · 2014-03-06 19:51:14Z

1

The regex pattern to look for is \d. So in python you would code it as:

pattern = re.compile(r'\d+')
result =  re.search(pattern, input_string)

edited Mar 6, 2014 at 19:51

answered Mar 6, 2014 at 18:16

shaktimaan

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2 Comments

ifryed Over a year ago

you need to write [\d]* with the * so it will catch all the number and not just the first digit.

shaktimaan Over a year ago

@ifryed You are right. We could alternatively do a \d+

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