Adding count of list elements into dictionary

Question

I am trying to add elements and their count in a list to a dictionary, but getting Type Error. Here is my code :

v= ["a","b","c","b","a"]

res= {}
for i in set(v):
    res.update( i = v.count[i] )
print(res)

The error I am getting is:

TypeError: 'builtin_function_or_method' object is not subscriptable

Your code should be a minimum reproducible example. I can't run the code you've provided and recreate your error. What is votes.count[i]? It's not defined. — Hayden Eastwood, Apr 11 '20 at 21:33
You mean `v.count(i)`, but this is *not* an efficient implementations, it is O(N**2) when you can do it in O(N) — juanpa.arrivillaga, Apr 11 '20 at 21:47

score 2 · Answer 1 · answered Apr 11 '20 at 21:35

2

You don't need to reinvent the wheel - you can use Python's Counter:

from collections import Counter
v = ["a","b","c","b","a"]
result = Counter(v)

And if you absolutely need a dictionary and not just an object that can act like one:

result = dict(Counter(v))

answered Apr 11 '20 at 21:35

Mureinik

`Counter` isn't merely "an object that can act like one", it *is* a `dict`, i.e. `isinstance(Counter(), dict)` is true – juanpa.arrivillaga Apr 11 '20 at 21:48

1 Answers1