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James Mills prologic at shortcircuit.net.au
Mon Dec 29 20:35:44 EST 2008 
On Tue, Dec 30, 2008 at 11:32 AM, James Mills
<prologic at shortcircuit.net.au> wrote:
> Ross, the others have informed you that you are not
> actually incrementing the count. I'll assume you've
> fixed your function now :) ... I want to show you a far
> simpler way to do this which takes advantage of
> Python's list comprehensions and mappings (which are
> really what dictionaries are):
>
>>>> s = "James Mills and Danielle Van Sprang"
>>>> dict([(k, len([x for x in s if x == k])) for k in s])
> {'a': 5, ' ': 5, 'e': 3, 'd': 1, 'g': 1, 'i': 2, 'M': 1, 'J': 1, 'm':
> 1, 'l': 4, 'n': 4, 'p': 1, 's': 2, 'r': 1, 'V': 1, 'S': 1, 'D': 1}
>>>>
>
> Let us know when you get to the "List Comprehension"
> section - They are very powerful - As as Generators
> and Generator Expressions.
>
> Have fun learning Python,

Also, here's a nice function:

>>> def histogram(s):
...     d = dict([(k, len([x for x in s if x == k])) for k in s])
...     for k, v in d.iteritems():
...             print "%s: %s" % (k, "*" * v)
...
>>> histogram("Hello World!")
!: *
 : *
e: *
d: *
H: *
l: ***
o: **
r: *
W: *

cheers
James
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