Count the occurrences of the elements in list

Question

I want to make a function that get a list, like:

['comp1', 'comp2', 'comp1', 'mycomp', 'mycomp']

And return a dictionary that the key's is the name of the computers and the values is how many times the same name\key's repeated in the list.

Like if the list get input:

["computer17", "computer6", "comp", "computer17"]

So the return is:

["computer17":"2",...]

What number do your expect for "comp"? – timgeb Dec 24 '15 at 12:57 — timgeb, Dec 24 '15 at 12:57
i changed the question @brunodesthuilliers – HelloWorld Dec 24 '15 at 13:03 — HelloWorld, Dec 24 '15 at 13:03
I changed the question @timgeb – HelloWorld Dec 24 '15 at 13:04 — HelloWorld, Dec 24 '15 at 13:04
I changed the question @VigneshKalai – HelloWorld Dec 24 '15 at 13:04 — HelloWorld, Dec 24 '15 at 13:04

score 4 · Accepted Answer · edited Dec 24 '15 at 13:22

The easiest to way to count the items in a list is using a Counter object (Counter is a child-class of the built in dictionary):

>>> from collections import Counter
>>> computers = ['computer17', 'computer6', 'comps', 'computer17']
>>> Counter(computers)
Counter({'computer17': 2, 'comps': 1, 'computer6': 1})

Excerpt from the docs:

class Counter(__builtin__.dict)

Dict subclass for counting hashable items. Sometimes called a bag or multiset. Elements are stored as dictionary keys and their counts are stored as dictionary values.

Count the occurrences of the elements in list

1 Answers1