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Khaled Koubaa
Khaled Koubaa

Reputation: 92

iterate on list by pair or triplets

I want to iterate on the list of files inside a specific folder, and store files names by pairs words or triplets words. I created this code:

for file_name in os.listdir(path):
    file_name_aslist = file_name.split()
    o = [(file_name_aslist[x], file_name_aslist [x+1]) for x in range(0, len(file_name_aslist ), 2)]

it returns this error:

IndexError: list index out of range

The expression work on single list, but dont want to work inside the loop: for example:

list = ['ra', 'ti', 'kaa', 'esss', 'fm', 'am']
print([(list[x], list[x+1]) for x in range(0, len(list), 2)])

[('ra', 'ti'), ('kaa', 'esss'), ('fm', 'am')]

also, when I try to iterate on triplets , refuse as well

print([(list[x], list[x+1], list[x+2]) for x in range(0, len(list), 3)])

IndexError: list index out of range

Upvotes: 0

Views: 860

Answers (3)

kederrac
kederrac

Reputation: 17322

you are splitting the names of the files by " " (space) at this line:

file_name_aslist = file_name.split()

you can not be sure that all the files have more than 1 word after splitting

what can you do:

def chunks_n(my_list, n):
    for e in range(0, len(my_list), n):
        yield my_list[e: e + n]

my_list = ['ra']
print(list(chunks_n(my_list, 2)))

output:

[['ra']]

Upvotes: 1

Dharmveer Singh
Dharmveer Singh

Reputation: 140

just add a if condition when length of the list is not multiple of 2 , append an extra empty string in the list to make it even. same for triplets. you have to add one or two string.

   #donot use split function.

file_name_aslist = os.listdir(path)
if len(file_name_aslist) // 2 == 0 :
   o = [(file_name_aslist[x], file_name_aslist [x+1]) for x in range(0, 
   len(file_name_aslist ), 2)]
else:
   file_name_aslist.append("")

   o = [(file_name_aslist[x], file_name_aslist [x+1]) for x in range(0, len(file_name_aslist ), 2)]

Upvotes: 1

boechat107
boechat107

Reputation: 1724

First thing: in your example using a "single list", list does not necessarily represent your original file_name_aslist. If your file names don't contain spaces, file_name_aslist will be a list with a single element, the file name itself. For these cases, it is very easy to verify why file_name_aslist [x+1] will throw a IndexError.

Do you really expect that file_name_aslist be a list with more than one element? Are you not trying to split by other criteria, like . (to possibly split by file extension, which is also a bad approach)?

Upvotes: 0

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