Extract a particular number followed by a command line argument variable from a string in python

Question

Firstly am saying this is not this : How to get integer values from a string in look here ..ok so

my question is : mv = /dev/vg10/lv10:cp:99 i need to extract vg10 's "10" not [10]. mv is a string

my final output should be only 10 that should extracted from vg

my python version: Python 2.6.1

Thanks in advance.. please help me :(

Are we missing a bit of this post, or is your version actually just loading the interpreter? — Jon Clements, Oct 19 '12 at 10:46

score 2 · Accepted Answer · edited Oct 19 '12 at 11:08

2

You should look into the regular expressions module of python. Simply "import re" in your script to provide regex capabilities. By the way if you only want the numbers following the string "vg" then the following script should do the trick.

import re
urString = "/dev/vg10/lv10:cp:99"
Matches = re.findall("vg[0-9]*", mv)
print Matches

Now matches will have a list containing all vg'number'. That [0-9]* means any digit any number of times. Parse it again to get the numbers from it. You should read more about regular expressions. It's fun.

Extending the answer to match OP's requirement:

In [445]: Matches
Out[445]: ['vg10']

In [446]: int(*re.findall(r'[0-9]+', Matches[0]))
Out[446]: 10

edited Oct 19 '12 at 11:08

avasal

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answered Oct 19 '12 at 10:58

Extn3389

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only the value should be 10 ..not vg10 – Sreeni Puthiyillam Oct 19 '12 at 11:01
I said parse the content again! – Extn3389 Oct 19 '12 at 11:05
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extending the answer... `int(*re.findall(r'[0-9]+', Matches[0]))` – avasal Oct 19 '12 at 11:10

score 1 · Answer 2 · answered Oct 19 '12 at 10:53

1

Are you talking about this:

import re
mv = "/dev/vg10/lv10:cp:99"
print re.search('/dev/vg(\d+)', mv).groups()

Or if vg can be something else, but it is always the second item you want you can do this:

print re.search('/dev/\w+(\d+)/lv10:cp:99', mv).groups()

answered Oct 19 '12 at 10:53

Alexander Stefanov

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No No vg not always 2nd itemmm :( – Sreeni Puthiyillam Oct 19 '12 at 10:57
`In [404]: int(re.search('/dev/vg(\d+)', mv).groups()[0])` `Out[404]: 10` – avasal Oct 19 '12 at 10:57
but be carefull, this will throw some error if nothing is matched – Alexander Stefanov Oct 19 '12 at 10:58
what exactly do you want to extract then? can you provide more details about this? and other example strings as well. – Alexander Stefanov Oct 19 '12 at 11:00
See Alex in this case : /dev/mapper/vg8-lv8-eSPAN_MAX_d4:eSPAN_MAX_d4:99 .... wht i do – Sreeni Puthiyillam Oct 19 '12 at 11:03
OK, if you are looking for 'vg[some number]', then Extn3389's answer is appropriate, it will give you the number immediately after 'vg', wherever it is. The question is: are you always interested in the number only after 'vg' string? – Alexander Stefanov Oct 19 '12 at 11:09

tetris555 · Answer 3 · 2012-10-22T06:36:20.310

0

import re

mv =  '/dev/mapper/vg8-lv8-eSPAN_MAX_d4:eSPAN_MAX_d4:99'

print re.findall(r'(?<=vg)\d*', mv)

edited Oct 22 '12 at 06:36

answered Oct 19 '12 at 14:34

tetris555

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When posting code, be sure to use four spaces (i.e., " ") before each line. This will format your text as a code block. – Garrett Hyde Oct 22 '12 at 00:58

Extract a particular number followed by a command line argument variable from a string in python

3 Answers3