How to calculate the percentage of each element in a list?

Question

I have this list with 5 sequence of numbers:

['123', '134', '234', '214', '223'] 

and I want to obtain the percentage of each number 1, 2, 3, 4 in the ith position of each sequence of numbers. For example, the numbers at 0th position of this 5 sequences of numbers are 1 1 2 2 2, then I need to calculate the percentage of 1, 2, 3, 4 in this sequence of numbers and return the percentage as 0th element of a new list.

['123', '134', '234', '214', '223']

0th position: 1 1 2 2 2   the percentage of 1,2,3,4 are respectively: [0.4, 0.6, 0.0, 0.0]

1th position: 2 3 3 1 2   the percentage of 1,2,3,4 are respectively: [0.2, 0.4, 0.4, 0.0]

2th position: 3 4 4 4 3   the percentage of 1,2,3,4 are respectively: [0.0, 0.0, 0.4, 0.6]]

Then desired result is to return:

[[0.4, 0.6, 0.0, 0.0], [0.2, 0.4, 0.4, 0.0], [0.0, 0.0, 0.4, 0.6]]

My attempt so far:

list(zip(*['123', '134', '234', '214', '223']))

Result:

 [('1', '1', '2', '2', '2'), ('2', '3', '3', '1', '2'), ('3', '4', '4', '4', '3')]

But I got stuck here, then I don't know how to calculate the percentage of the element of each numbers of 1, 2, 3, 4, then obtain the desired result. Any suggestion is appreciated!

Answer 1

starting from your approach, you could do the rest with a Counter

from collections import Counter

for item in zip(*['123', '134', '234', '214', '223']):
    c = Counter(item)
    total = sum(c.values())
    percent = {key: value/total for key, value in c.items()}
    print(percent)

    # convert to list
    percent_list = [percent.get(str(i), 0.0) for i in range(5)]
    print(percent_list)

which prints

{'2': 0.6, '1': 0.4}
[0.0, 0.4, 0.6, 0.0, 0.0]
{'2': 0.4, '3': 0.4, '1': 0.2}
[0.0, 0.2, 0.4, 0.4, 0.0]
{'4': 0.6, '3': 0.4}
[0.0, 0.0, 0.0, 0.4, 0.6]

Answer 2

You could start by creating the zipped list as you did:

zipped = zip(*l)

then map an itertools.Counter to it as to get the counts of each item in the results from zip:

counts = map(Counter, zipped)

and then go through it, creating a list out of their counts divided by their sizes:

res = [[c[i]/sum(c.values()) for i in '1234'] for c in counts]
print(res) 
[[0.4, 0.6, 0.0, 0.0], [0.2, 0.4, 0.4, 0.0], [0.0, 0.0, 0.4, 0.6]]

If you are a one-liner kind of person, mush the first two in the comprehension to get this in one line:

res = [[c[i]/sum(c.values()) for i in '1234'] for c in map(Counter, zip(*l))]

additionally, as noted in a comment, if you don't know the elements ahead of time, sorted(set(''.join(l))) could replace '1234'.