comparing lists of tuples

Question

I have the following code, comparing two lists that contains equally structured tuples:

list_one = [('id_01','aaa','bbb'), ('id_02','aaa','bbb'), ('id_03','aaa','bbb'), ('id_04','aab','bbc')]
list_two = [('id_01','aaa','bbb'), ('id_02','aaa','bbb'), ('id_03','aad','bbd')]
for tupl in list_one:
 for tup in list_two:
 if tupl[0] == tup[0] and (tupl[1] != tup[1] or tupl[2] != tup[2]):
 print("There is a difference on "+
 "{} between the two lists".format(tup[0]))

this code would print There is a difference on id_03 between the two lists which is the expected result. But I wonder if there is a better way to achieve the same result, maybe whitout iterating through list_two for every item of list_one, but any suggestion will be appreciated.

• Peilonrayz: If id_03 were the same in both lists what output would you expect?
• Celso Pereira Neto: Hi @Peilonrayz I understand it would be a good idea including this validation, but for my scope, I'm only concerned about the differences, i.e. this validation not returning anything would mean that everything is ok.
• RootTwo: Are the lists in order by id? That is, the tuple with id_01 is before the tuple with id_02, etc. The sample data has them in order; is that always the case?
• Celso Pereira Neto: No @RootTwo, and the real IDS are strings, like, "SOMETHING_OTHER_SOMETHING", without any kind of ordinance.

Answer 1

I think you would be better off using set. It provides features like set difference by itself, thereby reducing a lot of work at your end:

set_one = set([('id_01','aaa','bbb'), ('id_02','aaa','bbb'), ('id_03','aaa','bbb'), ('id_04','aab','bbc')])
set_two = set([('id_01','aaa','bbb'), ('id_02','aaa','bbb'), ('id_03','aad','bbd')])
for difference in (set_two - set_one):
 print(f"There is a difference on {difference[0]} between the two lists")

Answer 2

Looks like you should use a dictionary instead of a list. The id_01 in your case would be the key for each dictionary and the other items can be contained in a list.

Like this (same for dict_two)

dict_one = {
 'id_01': ['aaa', 'bbb'],
 'id_02': ['aaa', 'bbb'],
}

then you can iterate over the keys

for k in dict_one.keys():
 if dict_one[k][0] != dict_two[k][0] or dict_one[k][1] != dict_two[k][1]:
 print("there is a diff....")

• Peilonrayz: This doesn't work the same as the OP's
• user985366: It does what was asked for a better way to achieve the same result, maybe whitout iterating through list_two for every item of list_one, . What do you think is missing in my suggestion? The data structure used by OP seems inappropriate for what they want to do with it, don't you agree?
• hjpotter92: it'd raise an error for key id_04
• user985366: @hjpotter92 correct. I assumed too much