Question

I’m working Huffman coding of any .txt file, so first I need to analyse this text file. I need to read it, then analyse.
I need “exit” like table:

---

letter | frequency(how many times same latter repeated) | Huffman code(this will come later)

---

I started with:

 f = open('test.txt', 'r')    #open test.tx
 for lines in f:
     print lines          #to ensure if all work...

---

How can I order reading characters from file in alphabetic order:

with open("test.txt") as f_in:
    for line in f_in:
        for char in line:
            frequencies[char] += 1

???Many thanks

---

Well I tried like this:
frequencies = collections.defaultdict(int)
with open("test.txt") as f_in:
    for line in f_in:
        for char in line:
            frequencies[char] += 1


 frequencies = [(count, char) for char, count in frequencies.iteritems()]
 frequencies.sort(key=operator.itemgetter(1))

But compiler return me an “error”
enter code here

I need this alphabetic order in for loop, not at end at frequencies…

Answer 1

To get your table of frequencies, I would use a defaultdict. This will only iterate over the data once.

import collections
import operator

frequencies = collections.defaultdict(int)
with open(filename) as f_in:
    for line in f_in:
        for char in line:
            frequencies[char] += 1


frequencies = [(count, char) for char, count in frequencies.iteritems()]
frequencies.sort(key=operator.itemgetter(1))