Question

I’m having some problems with a piece of python work. I have to write a piece of code that is run through CMD. I need it to then open a file the user states and count the number of each alphabetical characters it contains.

So far I have this, which I can run through CDM, and state a file to open. I’ve messed around with regular expressions, still can’t figure out how to count individual characters. Any ideas? sorry if I explained this badly.

import sys
import re


filename = raw_input()
count = 0
datafile=open(filename, 'r')

Answer 1

I’d stay away from regexes. They’ll be slow and ugly. Instead, read the entire file into a string, and use the built-in string method count to count the characters.

To put it together for you:

filename = raw_input()
datafile=open(filename, 'r')
data = datafile.read()
datafile.close() # Don't forget to close the file!
counts = {} # make sure counts is an empty dictionary
data = data.lower() # convert data to lowercase
for k in range(97, 123):  # letters a to z are ASCII codes 97 to 122
    character = chr(k) # get the ASCII character from the number
    counts[character] = data.count(character)

Then, you have a dictionary counts containing all the counts. For example, counts['a'] gives you the number of as in the file. Or, for the entire list of counts, do counts.items().