python - check if list entry is contained in string

Question

I have a script where I'm walking through a list of passed (via a csv file) paths. I'm wondering how I can determine if the path I'm currently working with has been previously managed (as a subdirectory of the parent).

I'm keeping a list of managed paths like this:

pathsManaged = ['/a/b', '/c/d', '/e']

So when/if the next path is '/e/a', I want to check in the list if a parent of this path is present in the pathsManaged list.

My attempt so far:

if any(currPath in x for x in pathsManaged):
   print 'subdir of already managed path'

This doesn't seem to be working though. Am I expecting too much from the any command. Are there any other shortcuts that I could use for this type of look-up?

Thanks

What is currPath? Could you give few examples and expected result? — m.wasowski
– m.wasowski, Commented Mar 28, 2014 at 10:11

Dan D. · Accepted Answer · 2014-03-28 10:23:09Z

2

Perhaps:

from os.path import dirname

def parents(p):
    while len(p) > 1:
        p = dirname(p)
        yield p

pathsManaged = ['/a/b', '/c/d', '/e']

currPath = '/e/a'

if any(p in pathsManaged for p in parents(currPath)):
    print 'subdir of already managed path'

prints:

subdir of already managed path

edited Mar 28, 2014 at 10:23

answered Mar 28, 2014 at 10:15

Dan D.

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Comments

RemcoGerlich · Accepted Answer · 2014-03-28 10:22:13Z

0

Assuming that pathsManaged contains absolute paths (otherwise I think all bets are off), then you could make currPath an absolute path and see if it starts with any of the paths in pathsManaged. Or in Python:

def is_path_already_managed(currPath):
    return any(
        os.path.abspath(currPath).startswith(managed_path)
        for managed_path in pathsManaged)

Also conceptually I feel pathsManaged should be a set, not a list.

answered Mar 28, 2014 at 10:22

RemcoGerlich

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3 Comments

Toolagio Over a year ago

Thanks. As I'm relatively new to python, I'm curious to know why a set would be preferred over a list in this case.

RemcoGerlich Over a year ago

A list works just fine too, but as it should never contain the same path twice, order doesn't matter, and the only thing that really matters is "is this path in pathsManaged or not", the concept that comes closest to that is a set.

Toolagio Over a year ago

Thanks RemcoGerlich, I'll be using this advice next time.

m.wasowski · Accepted Answer · 2014-03-28 10:23:34Z

0

If I understand you correctly, you want to check if any of pathsManaged is part of currPath, but you are doing this other way around. Depending on what you want, one of this should work for you:

any(x in currPath for x in pathsManaged)

any(currPath.startswith(x) for x in pathsManaged)

os.path.dirname(currPath) in pathsManaged

edited Mar 28, 2014 at 10:23

answered Mar 28, 2014 at 10:13

m.wasowski

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2 Comments

msvalkon Over a year ago

If currPath is '/e/a' then this will return True if there's '/' or '/a' in the list..

m.wasowski Over a year ago

if only start of path should be taken into account, any(currPath.startswith(x) for x in pathsManaged) might be better, or os.path.dirname(currPath) in pathsManaged, but I am not sure what exactly OP expects.

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