unique elements from list of lists

[azrael]

try something else. im posting the code from a kiosk which has no
python, sooo..... no code. only explanation

if my memory works well there is a function in python that takes a
multidimensional list and returns its values as a one-dimension list.

def main():
   list =unknownFunction([['a', 'b', 'd'], ['b', 'c'], ['a', 'c',
'd'])        # =a, b, d, b, c, a, c, d
   temp = []
   for i in list:
      check(i, temp, list)
   sort(list)

def check(pos, temp, list ):
   for i in temp:
      if temp[i]== list[pos]
         del list[pos]
         check(pos, temp, list)
      temp.append(list[pos])

im not sure if this should work but the meaning is:
the first three elements will be  appended into the list directly
because there was no like this in the temp
while there are elements in the list take a pivot value and check if
they are unique in the list.

check:
 while there are elements in the temporary list check if the pivot
exists in the temp. if false then append it to temp.

if true delete the element and go into the recursion on the same index
 why?

temp a, b, d
list a, b, d, (b), c, a, c, d

temp a, b, d
list a, b, d, (c) a, c, d

temp a, b, d, c
list a, b, d, c, (a) c, d

temp a, b, d, c
list a, b, d, c, (c), d

temp a, b, d, c
list a, b, d, c, (d)


temp a, b, d, c
list a, b, d, c

list a, b, c, d

one way to do it. this works well if you need the list in the order
they appear. sort it and it works well


but i think that there is the possibility to do it somthing like the
merge sort. maybee it would work. try it. Merge the sublists and
remove the duplicates. (L1,L2,L3) -> (L12, L3) -> (L123)
this should work pretty well




Tekkaman je napisao/la:
> I have a list of lists and I want to define an iterator (let's call
> that uniter) over all unique elements, in any order. For example,
> calling:
>
> sorted(uniter([['a', 'b', 'd'], ['b', 'c'], ['a', 'c', 'd']]))
>
> must return ['a', 'b', 'c', 'd']. I tried the following
> implementations:
>
> from itertools import chain
> def uniter1(listOfLists):
>     for item in set(chain(*listOfLists)): yield item
>
> def uniter2(listOfLists):
>     for item in reduce(
>         lambda x,y: x|y,
>         [set(list_) for list_ in listOfLists]
>         ): yield item
>
> speed test with timeit says the first one is slightly faster. What
> bothers me is that it builds a set from an iterator and then another
> iterator from the set. Is there a way to implement this using only
> iterators? I also tried a "full python" implementation (by that I mean
> one that does not use the built-in set and keeps track of previously
> yielded items in a list) but the one I pulled out is about 180 times
> slower. Here it is:
>
> def uniter3(listOfLists):
>     done = []
>     for list_ in listOfLists:
>         for item in list_:
>             if not item in done:
>                 done.append(item)
>                 yield item
>
> Thanks in advance for any contribution.
>
> -- Simone