from math import sqrt
from collections import Counter

def forSearch():
    words = {'bit':{1:3,2:4,3:19,4:0},'shoe':{1:0,2:0,3:0,4:0},'dog':{1:3,2:0,3:4,4:5}, 'red':{1:0,2:0,3:15,4:0}}
    search = {'bit':1,'dog':3,'shoe':5}
num_files = 4 # TODO: , figure this out programatically

    file_relevancy = Counter()
    c = sqrt(sum([x**2 for x in search.values()]))
    for i in range(1, num_files+1):
        words_ith_val = [words[x][i] for x in search.keys() ]
        a = sum([search[key] * words[key][i] for key in search.keys()])
        b = sqrt(sum([x**2 for x in words_ith_val]))
        file_relevancy[i] = (a / (b * c))

    return [x[0] for x in file_relevancy.most_common(num_files)]

print forSearch()

for i in range(1, num_files+1):
    if corresponding key in words cannot be found
        insert it and make its value = 0
    words_ith_val = [words[x][i] for x in search.keys() ]