Function not returning variable defined externally

Question

I have nested functions that are meant to partition the indices of a list of lists, corresponding to elements (lists) that are the same.

My first attempt wasn't returning the list I needed from an inside function. i thought it was because the output list was created inside the function only. So I modified the script. I now define my output list, liketissuesets, exernally. It is passed to, and modified by, the internal functions. And yet, the correctly modified list is not passing from the function ind_list_renew to the function find_like_tissues_set!

#!/usr/bin/env python

import numpy as np

l1 = [1,2,3]

l2=[2,3]

l3=[1,2,3]

l4=[2,3,4]

l5=[2,3]

mylist = [l1,l2,l3,l4,l5]
liketissuesets = []

def listidentity(v,b,f):
    if len(v) != len(b):
        return []
    else:
        for j in range(len(b)):
            if v[j]!=b[j]:
                return []
            else:
                return [f]


def ind_list_renew(changinglist, liketissuesets):
    a=changinglist[0]
    b=mylist[a]
    common = []

    for f,v in enumerate(mylist):
        common = common + listidentity(v,b,f)

    print(common)
    liketissuesets = liketissuesets + [common]
    print(liketissuesets)
    changinglist = changinglist.tolist()
    indtodelete = [j for j,k in enumerate(changinglist) if k in common]
    changinglist = np.delete(changinglist, indtodelete)

    if len(changinglist) != 0:
        ind_list_renew(changinglist, liketissuesets)
    else:
        print('yay', liketissuesets)
        return liketissuesets


def find_like_tissues_set(mylist, liketissuesets):

    indoriginal = np.arange(len(mylist))
    c=ind_list_renew(indoriginal, liketissuesets)
    print(c)
    return c

b=find_like_tissues_set(mylist, liketissuesets)

print(b)

Your recursive call should be: return ind_list_renew(changinglist, liketissuesets). — quamrana
– quamrana, Commented Aug 9, 2019 at 9:56
@quamranaI have changed one function to def find_like_tissues_set(mylist, liketissuesets): return ind_list_renew(np.arange(len(mylist)), liketissuesets) But I still get None return! — Meep
– Meep, Commented Aug 9, 2019 at 10:01

quamrana · Accepted Answer · 2019-08-09 10:01:32Z

1

Really, you don't need the global liketissuesets. You can restructure your code like this:

def ind_list_renew(changinglist, liketissuesets):
    # stuff omitted

    if len(changinglist) != 0:
        return ind_list_renew(changinglist, liketissuesets)
    else:
        print('yay', liketissuesets)
        return liketissuesets


def find_like_tissues_set(mylist):
    indoriginal = np.arange(len(mylist))
    c = ind_list_renew(indoriginal, [])
    print(c)
    return c

b = find_like_tissues_set(mylist)

print(b)

answered Aug 9, 2019 at 10:01

quamrana

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