Letter frequency in python

Question

I need to make a program that prints out the frequency of letters in a text file and compares that frequency with that of another in python.

So far I am able to prin

Answer 1

I think this is a really straight forward way to do it:

while True:
    speech = raw_input("Enter file name:")

    wholeFile = open(speech, 'r+').read()
    lowlet = wholeFile.lower()

    alphas = 'abcdefghijklmnopqrstuvwxyz'

    # lets set default values first
    occurrences = {letter : 0 for letter in alphas }
    # occurrences = dict(zip(alphas, [0]*len(alphas))) # for python<=2.6

    # total number of valid letters
    total = 0

    # iter everything in the text
    for letter in lowlet:
        # if it is a valid letter then it is in occurrences
        if letter in occurrences:
            # update counts
            total += 1
            occurrences[letter] += 1

    # now print the results:
    for letter, count in occurrences.iteritems():
        print letter, (1.0*count/total)

As you notices you need the total number of valid letters in the text before you can calculate the frequency. Either you filter the text before processing it, or you combine the filtering with the processing, which is what I do here.