Help me to understand! Why does the function append 1 for each key?

Question

I need 1 to be added only by key to the corresponding list item. But the function adds 1 for each key.
https://code.sololearn.com/cjdfPrSWZnrd/?ref=app

Answer 1

When you do (x[i] = value) on line 11 you put the reference to e in every key in x, therefore when you seemingly append 1 to one key's list, you, in fact, append to all of them and in the end you get a dict of n 1s for each key where n is how many words you get.

To avoid that use x[i] = value[:], or the more readable, x[i] = value.copy().

Or... you could just rethink this more simply and write:

words = input().lower().split()
count_dict = {}

for word in words:
count_dict[word] = count_dict.get(word, 0) + 1

print(count_dict)

Note:
dict.get(key, default=None) does the following:
if key in dict: return dict[key]
else: return default

This avoids a nasty KeyError.

Refer to this discussion for more info:
https://www.sololearn.com/Discuss/2235829/?ref=app

Answer 2

thank you very much! you really helped!

Answer 3

Dmitry Bezruchko So, just recently I discovered Counter:

>>> from collections import Counter
>>> Counter('apple apple banana orange banana apple'.split())

Counter({'apple': 3, 'banana': 2, 'orange': 1})

Python was a good choice :)