Calculate all three averages in Python. Intended for command-line use.

avg.py

#!/usr/bin/python3

import sys
import operator

numbers = sys.argv[1].split(",")

if len(sys.argv) > 2:
    type = sys.argv[2]
else:
    type = "mean"

if type == "median":
    numbers.sort()
    if len(numbers) % 2 == 0:
        med = [numbers[round(len(numbers)/2)-1], numbers[round(len(numbers)/2)]]
    else:
        med = numbers[round(len(numbers)/2)]
    print(med)
elif type == "mode":
    occurences = {}
    result = None
    for n in numbers:
        occurences[n] = numbers.count(n)
    occurences_sorted = sorted(occurences.items(), key=operator.itemgetter(1))
    occurences_sorted.reverse()
    print(occurences_sorted[0][0])
else:
    sum = 0
    for n in numbers:
        sum += float(n)
    sum /= len(numbers)
    print(sum)