Question

For this function,I want to count each elements’ occurrences and return a dict.
such as: [a,b,a,c,b,a,c]
and return {a:3,b:2,c:2}
How to do that?

Answer 1

You can use Counter then:

from collections import Counter
Counter( ['a','b','a','c','b','a','c'] )

Or DefaultDict:

from collections import defaultdict
d = defaultdict(int)
for x in lVals:
    d[x] += 1

OR:

def get_cnt(lVals):
    d = dict(zip(lVals, [0]*len(lVals)))
    for x in lVals:
        d[x] += 1
    return d