For loop not updating my list as expected in python

Question

I'm struggling with this code not outputing what I'm expecting.

Here the code:

'base' is a list of sets

'items' is a list of str

base = [{'🌭', '🍔'},{'🌭', '🍕'},{'🌮', '🍔'},{'🌮', '🍕'},{'🍆', '🍑'}]
items = ['🌭','🍔','🍕','🌮','🍆','🍑']

for i in items:
    for j in base:
        j.add(i)

My result is this if I print base

[{'🌭', '🌮', '🍆', '🍑', '🍔', '🍕'},
 {'🌭', '🌮', '🍆', '🍑', '🍔', '🍕'},
 {'🌭', '🌮', '🍆', '🍑', '🍔', '🍕'},
 {'🌭', '🌮', '🍆', '🍑', '🍔', '🍕'},
 {'🌭', '🌮', '🍆', '🍑', '🍔', '🍕'}]

But I'm looking to have something like this, where every item on items gets added to every set in base.


[{'🌭', '🌭', '🍔'},
 {'🍔', '🌭', '🍔'},
 {'🍕', '🌭', '🍔'},
 {'🌮', '🌭', '🍔'},
 {'🍆', '🌭', '🍔'},
 {'🍑', '🌭', '🍔'},
 {'🌭', '🌭', '🍕'},
 {'🍔', '🌭', '🍕'},
 {'🍕', '🌭', '🍕'},
 {'🌮', '🌭', '🍕'},
 {'🍆', '🌭', '🍕'},
 {'🍑', '🌭', '🍕'},
...]

I don't understand the question. You say you want "every item on items gets added to every set in base", and isn't that exactly what happened? You have five base sets, and they each ended up containing every item. — John Gordon
– John Gordon, Commented Apr 7, 2020 at 14:58

dman · Accepted Answer · 2020-04-07 15:09:54Z

1

You won't get what you need with sets, which don't allow you to repeat items. Convert it to list, and then flip the loop:

base = [{'🌭', '🍔'},{'🌭', '🍕'},{'🌮', '🍔'},{'🌮', '🍕'},{'🍆', '🍑'}] items = ['🌭','🍔','🍕','🌮','🍆','🍑'] base2 = [] for i in base: for j in items: k = list(i).copy() k.append(j) base2.append(k) base2

answered Apr 7, 2020 at 15:09

dman

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