For some reason this look alien to me. Can someone explain this?

Question

tuple = {}
tuple[(1, 2, 3)] = 8
tuple[(4, 2, 1)] = 10
tuple[(1, 2)] = 12
_sum = 0

for k in tuple:
_sum += tuple[k]

print(len(tuple) + _sum)

Answer 1

Hello cryptic blake

You have a dictionary called tuple (btw a bad name)

The keys of your dictionary are tuples and 8, 10 and 12 are the values.

If you print your dictionary:
{(1,2,3):8 , (4,2,1):10, (1,2):12}

Now you loop through the keys and add each value of this key to _sum

k is (1,2,3) -> add 8 to sum
k is (4,2,1) -> add 10 to sum
k is (1,2) -> add 12 to sum

Sum is 30 + length of your dictionary which is 3.
So you get 33 as output.

Answer 2

Hi!

I don’t know that you trying to do, but it it is strange to call a dictionary a tuple?!

You can never assign a value to a created tuple, because it’s imutable.

So what you are doing is a assigning values to a dictionary, called ’tuple’, using a tuples as keys.

If you use ’tuple’ as a variable name you have to delete before you can use the inbuilt function tuple(). Better find another name like

mydict = {}

In the for loop you scan over the dictionaries keys, return there values and sum them up in _sum. But you are missing a parentheses in the print function. The result will be the sum of the values plus the length of the dictionary (the number of keys in the dictionary): 3 + (8+10+12) = 33).

Answer 3

I guess what I didn't know is that a dictionary can have a tuple as key.

This is a question I got from a Python challenge

This learning process can be confusing sometimes lol. Simple stuff can seem difficult when treated with difficulty🥴

Anyways thank you all for your invaluable help!

Answer 4

cryptic blake

In short: keys must be immutable and tuples are immutable. So you can use tuples as keys.
https://www.askpython.com/JUMP_LINK__&&__python__&&__JUMP_LINK/dictionary/python-dictionary-dict-tutorial