How to combine string elements of a list for Apriori Algorithm in python?

Question

So I am trying to program Apriori Algorithm. I have here

L1= ['apple', 'banana','orange','mango]

This list already passed the support threshold, now I have to combine the items for another support threshold which should look like this:

C2 = [['apple','banana'],['apple','orange'],['apple','mango']]

Are you just looking for something like `l = L1.pop(0)` and `C2 = [[l, val] for val in L1]`? Or something more specific? — Sam Szotkowski, Apr 04 '21 at 05:26
No. I'm looking for an answer to combine each element like C2 = [['apple','banana'],['apple','orange'],['apple','mango']] then C3 will be [[banana, orange],[banana,mango]] — Messy Maze, Apr 04 '21 at 05:42

RJ Adriaansen · Answer 1 · 2021-04-04T06:22:25.553

1

L1= ['apple', 'banana','orange','mango']
C2 = [[L1[0], i] for i in L1[1:]]

Result C2:

[['apple', 'banana'], ['apple', 'orange'], ['apple', 'mango']]

To run this for all items in the list:

C2 = []
for i in L1:
    l = [[i, x] for x in L1 if not i == x]
    C2.extend(l)

edited Apr 04 '21 at 06:22

answered Apr 04 '21 at 05:37

RJ Adriaansen

thank you! but what should i do if i will combine the next elements with other elements like [['banana','orange'],['banana','mango']]? Note that it skips ['banana', 'apple'] since it's the same with ['apple', 'banana'] – Messy Maze Apr 04 '21 at 05:46
You should use list.pop(0) to create the lists in a loop for i in range(len(L1)), that way you won't have duplicates. – Sam Szotkowski Apr 04 '21 at 05:50
it returned an empty list when i used the pop – Messy Maze Apr 04 '21 at 06:12
@MessyMaze in that case we'd have to include another for loop, I have updated the answer. Don't use `pop` because it removes items from L1. – RJ Adriaansen Apr 04 '21 at 06:23

1 Answers1