code for split a list of items into list (split function) in python

Question

I have a function to split the list, example

def split(*arg):
    row = len(arg[0])
    col = len(arg)
    new = [row * col]
    for i in row:
        for j in col:
            new[j][i] = arg[i][j]
    return new

    # this is method for split the list but it is include errors

Desired output:

list_a = [(1,2,3),(8,9,10),(100,20,15)]

split (list_a) 
[(1,8,100),(2,9,20),(3,10,15)]

based on expected output I'd say you are trying to find the [transpose](http://docs.scipy.org/doc/numpy-1.10.1/reference/generated/numpy.transpose.html) — Tadhg McDonald-Jensen, Mar 01 '16 at 21:03
Does this answer your question? [Transpose list of lists](https://stackoverflow.com/questions/6473679/transpose-list-of-lists) — Karl Knechtel, Aug 31 '23 at 18:48

score 0 · Answer 1 · edited May 23 '17 at 12:07

0

This is very similar to Transpose nested list in python.

However, you want a list of tuples as the result, so we don't even need a list comprehension. Just

list_a = [(1,2,3),(8,9,10),(100,20,15)]

zip(*list_a)  # Python 2
# or
list(zip(*list_a))  # Python 3
# [(1, 8, 100), (2, 9, 20), (3, 10, 15)]

This uses argument unpacking and the built-in zip function.

edited May 23 '17 at 12:07

Community

1
1

answered Mar 01 '16 at 21:32

das-g

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score 0 · Answer 2 · edited May 23 '17 at 10:28

based on the desired output it seems you are trying to find the transpose so you could do it with numpy like this:

import numpy
list_a = [(1,2,3),(8,9,10),(100,20,15)]
transpose_a = numpy.transpose(list_a)
print(transpose_a)
#or
#print(list(transpose_a))

But your split is malfunctioning for a few reasons reasons:

you are using *arg perameter but not unpacking the argument so you need to call it like split(*list_a)
new = [row * col] is creating a new list with one item instead of a two dimensional list.
you are iterating over integers instead of using range(row) and range(col).
row and col need to be swapped: row = len(arg) and col = len(arg[0]) since you use row as first dimension and col as second.

Although it occurs to me that this is what zip is designed to do so maybe you just need to use that instead.

code for split a list of items into list (split function) in python

2 Answers2