How do I iterate through a string in Python? -

as example, lets wanted list frequency of each letter of alphabet in string. easiest way it?

this example of i'm thinking of... question how make alltheletters equal said letters without alltheletters = "abcdefg...xyz". in many other languages letter++ , increment way through alphabet, far haven't come across way in python.

def alphcount(text):   lowertext = text.lower()   letter in alltheletters:       print letter + ":", lowertext.count(letter) 

the question you've asked (how iterate through alphabet) not same question problem you're trying solve (how count frequency of letters in string).

you can use string.lowercase, other posters have suggested:

import string alltheletters = string.lowercase 

to things way you're "used to", treating letters numbers, can use "ord" , "chr" functions. there's absolutely no reason ever this, maybe comes closer you're trying figure out:

def getalltheletters(begin='a', end='z'):     beginnum = ord(begin)     endnum = ord(end)     number in xrange(beginnum, endnum+1):         yield chr(number) 

you can tell right thing because code prints true:

import string print ''.join(getalltheletters()) == string.lowercase 

but, solve problem you're trying solve, want use dictionary , collect letters go:

from collections import defaultdict     def letteroccurrances(string):     frequencies = defaultdict(lambda: 0)     character in string:         frequencies[character.lower()] += 1     return frequencies 

use so:

occs = letteroccurrances("hello, world!") print occs['l'] print occs['h'] 

this print '3' , '1' respectively.

note works unicode well:

# -*- coding: utf-8 -*- occs = letteroccurrances(u"héĺĺó, ẃóŕĺd!") print occs[u'l'] print occs[u'ĺ'] 

if try other approach on unicode (incrementing through every character) you'd waiting long time; there millions of unicode characters.

to implement original function (print counts of each letter in alphabetical order) in terms of this:

def alphcount(text):     character, count in sorted(letteroccurrances(text).iteritems()):         print "%s: %s" % (character, count)  alphcount("hello, world!")