What is the mechanism behind this code?
pocet_piv = { 'Petr' : 6 , 'Pavel' : 7, 'Martin': 4}
for whatever in pocet_piv:
print(whatever, pocet_piv[whatever])
I would expect that pocet_piv[whatever] brings me a key from the dictionary, not the value. Who devised the logic for it to come up with the value, and why?
Why would you expect that?
Iterating through a dict yields its keys in insertion order. dictionary[key] returns the value corresponding to key.
Because for loop iterates over keys. So pocet_piv[whatever] looks for keys in pocket_piv. That would me my understanding.
Correct.
That makes no sense. whatever is already a key, per your previous sentence.
Yup, if whatever is already the key so print(pocet_piv[whatever]) would print the key in pocet_piv dictionary. So the question is, how was born the logic it prints the value.
Let’s take a step back.
d = {"key": "value"}
print(d["key"])
What do you think this will print?
I think it will print "value".
Correct. So why would would you expect it to behave differently in your example above?
Some glimpse of it from Raymond Hettinger’s Transforming Code into Beautiful, Idiomatic Python - Dictionary skills
Keys in dictionary are similar to indexes in ordered sequences differences being that keys can be arbitrary hashable values whether indexes are sequential integers starting from zero.
items = ['bacon', 'ham', 'spam']
items[0]
# should it return 0 or 'bacon'?
# if 'bacon' why should dictionary keys be different?
# if 0 then how 'bacon' is accessible?
What would that look like? What should be printed?
I’m not sure if this is an issue of mixed-up terminology or something else.
Yeah, I guess this is the type of answer I was looking for. Thx.