In Python, how should one extract the second-last directory name in a path?

Question

I have a string like the following:

/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore

How should I extract the "2.0.24" from this string? I'm not sure how to split the string using the slashes (in order to extract the second last element of the resultant list) and I'm not sure if this would be a good approach. What I have right now is the following:

"/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore".split("/RootCore")[0].split("AnalysisTop/")[1]

The number is changeable or not? – GLHF Feb 05 '15 at 15:54 — GLHF, Feb 05 '15 at 15:54

score 12 · Answer 1 · answered Feb 05 '15 at 15:57

12

You can also do:

import os
x = "/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore"
os.path.split(os.path.split(x)[0])[1]

results in

'2.0.24'

answered Feb 05 '15 at 15:57

AlG

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I don't understand why you received a down vote. It is an interesting approach. – Maxime Chéramy Feb 05 '15 at 16:02

score 9 · Accepted Answer · answered Feb 05 '15 at 15:54

9

'/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore'.split('/')[-2]

answered Feb 05 '15 at 15:54

Slam

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This is not portable across all filesystems. E.g., Windows uses a `\` to separate directories – tcmoore3 Apr 18 '17 at 16:45

Daniel Braun · Answer 3 · 2019-08-06T10:20:49.180

5

cross platform solution:

import os
'your/path'.split(os.path.sep)[-2]

edited Aug 06 '19 at 10:20

answered Apr 17 '19 at 14:32

Daniel Braun

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score 3 · Answer 4 · answered Feb 05 '15 at 15:54

3

Just split according to the / symbol then print the second index from the last.

>>> x = "/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore"
>>> y = x.split('/')
>>> y[-2]
'2.0.24'

answered Feb 05 '15 at 15:54

Avinash Raj

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So what if the string has more than 2 strings at the end? split('/')[-2] will fail – GLHF Feb 05 '15 at 15:59

ZdaR · Answer 5 · 2015-02-05T16:02:02.557

-1

path = "/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore"
path_dirs = path.split("/")

>>>> path_dirs
>>>> ['', 'cvmfs', 'atlas.cern.ch', 'repo', 'sw', 'ASG', 'AnalysisTop', '2.0.24', 'RootCore']

>>>> print path_dirs[-2]
>>>> '2.0.24'

edited Feb 05 '15 at 16:02

answered Feb 05 '15 at 15:55

ZdaR

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Sorry fixed it ! @Trengot – ZdaR Feb 05 '15 at 16:00

score -2 · Answer 6 · answered Feb 05 '15 at 15:56

-2

import re

str1 = "/cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisTop/2.0.24/RootCore"
t = re.findall("[0-9][.]*",str1)
print ("".join(t))

You can use regex-findall method. t returns a list, so using join().

Output;

>>> 
2.0.24
>>> 

# print (t)
>>> 
['2.', '0.', '2', '4']
>>>

answered Feb 05 '15 at 15:56

GLHF

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This is not the best solution. It might work in this case but not generic. what if you have /aaa/bbb/11/a/13/ ... – Bhanu Kaushik Feb 05 '15 at 15:58
So what if the string has more than 2 strings at the end? `split('/')[-2]` will fail. Dots are not change probably, so it's the best one I guess. – GLHF Feb 05 '15 at 15:59

In Python, how should one extract the second-last directory name in a path?

6 Answers6

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