CODEWITHSUNDEEP
pythonlistfilter
BubbleMonster
BubbleMonster

Reputation: 1416

Python: filter on a list returning empty list

I've done an OS walk and appended the results to a list.

exportFolder = []

for files in os.walk(exportLocation):
   exportFolder.append(files)

This is the list that is being stored as exportFolder:

[('/home/simon/Desktop/Windows.edb.export', [], ['MSysUnicodeFixupVer2.2', 'SystemIndex_0P.6', 'SystemIndex_0A.7', 'SystemIndex_GthrPth.5', 'SystemIndex_Gthr.4', 'MSysObjects.0', '__NameTable__.3', 'MSysObjectsShadow.1'])]

I want to search the list for the file 'SystemIndex_0A'

so I use:

filter(lambda x: 'SystemIndex_0A' in x, exportFolder)

The results bring back an empty list: []

I can see that the exportFolder list seems to be a list inside a list. How can I get my filter to work?

I want to print the SystemIndex_OA file from the list

Thanks in advance.

Upvotes: 0

Views: 831

Answers (1)

dawg
dawg

Reputation: 103874

Maybe rewrite your walk loop to look something more like this:

tgt=[]
for root, dirs, files in os.walk(exportLocation):
    for file in files:
        if 'SystemIndex_0A' in file:
            tgt.append(os.path.join(root, file))

Then you don't need to filter a nested list of tuples.

If you want to use a list of tuples produces by os.walk, you would do something like this (using your example, so we will only use the first tuple):

>>> LoT=[('/home/simon/Desktop/Windows.edb.export', [], ['MSysUnicodeFixupVer2.2', 'SystemIndex_0P.6', 'SystemIndex_0A.7', 'SystemIndex_GthrPth.5', 'SystemIndex_Gthr.4', 'MSysObjects.0', '__NameTable__.3', 'MSysObjectsShadow.1'])]
>>> 
>>> path, dirs, files=LoT[0]
>>> path
'/home/simon/Desktop/Windows.edb.export'
>>> dirs
[]
>>> files
['MSysUnicodeFixupVer2.2', 'SystemIndex_0P.6', 'SystemIndex_0A.7', 'SystemIndex_GthrPth.5', 'SystemIndex_Gthr.4', 'MSysObjects.0', '__NameTable__.3', 'MSysObjectsShadow.1']

Now that you have used tuple unpacking to unpack the tuple, you can use your filter statement:

>>> filter(lambda x: 'SystemIndex_0A' in x, files)
['SystemIndex_0A.7']

So if you had a whole list of tuples, you would use two nested loops.

Upvotes: 1

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