计算文件中的字母频率并写入输出文件python

Question

I am writing a function that take a in_file and checks the frequency of the letters in that file and writes in this format (letter:frequency) to a out_file.This is what i got so far can anyone help?

def count_letters(in_file,out_file):
    in_file = open(in_file,"r")
    out_file = open(out_file,"w")
    for line in in_file:
        words = line.split()
        for word in words:
            for letter in word:
                print(letter,':',line.count(letter),file=out_file,end="\n")

Answer 1

There is no need to split words, at all; directly passing a string to the counter updates the counts per character. You also need to collect all counts first , and only then write them out to the output file:

from collections import Counter

def count_letters(in_filename, out_filename):
    counts = Counter()
    with open(in_filename, "r") as in_file:
        for chunk in iter(lambda: in_file.read(8196), ''):
            counts.update(chunk)
    with open(out_filename, "w") as out_file:
        for letter, count in counts.iteritems():
            out_file.write('{}:{}\n'.format(letter, count)

Note that the inputfile is processed in 8kb chunks rather than in one go; you can adjust the block size (preferably in powers of 2) to maximize throughput.

You could use .most_common() instead of .iteritems() here if you want your output file to be sorted by frequency (descending).

Answer 2

This should do the trick - it counts all charaters, not only letters:

def count_letters(in_file,out_file):
    from collections import Counter
    in_file = open(in_file,"r")
    out_file = open(out_file,"w")
    letter_counts = Counter()
    with open(in_file, 'r') as in_file:
        for line in in_file:
            line = line.strip()
            for letter in line:
                # Count only letters.
                if not letter.isalpha():
                    continue
                letter_counts[letter] += 1

    with open(out_file, 'w') as out_file:
        for letter, count in letter_counts.iteritems():
            out_file.write('{}:{}\n'.format(letter, count))