[Tutor] Re: Using a dictionary to keep a count

[Karl Pflästerer]

On  4 Aug 2003, Levy Lazarre <- levy.lazarre at mfms.com wrote:

> Thanks for the clarification and suggestion, however this approach doesn't
> work for it doesn't create the intended dictionary of dictionaries
> structure.

Sorry I overlooked that need.

[...]

> The following approach using exceptions seems to work:
> ###############################################
> dic ={} 

Try to avoid global variables whenever possible.


[Code with try/except]

> Any comments? Is this a bad style? I was trying to make the code shorter
> with setdefault(), but it appears very difficult to use with nested
> structures.

No code with try/except is most of the times good style.  Here is an
example how your desire could be achieved with setdefault.

def process_log_file(name):
    d = {}
    f = open(name)
    for line in f:
        script, address = process_line(line)
        d.setdefault(script, {})
        d[script][address] = d[script].setdefault(address,0) + 1
    f.close()
    for (key, value) in d.items():
        print key , '=>'
        for (subkey, subvalue) in value.items():
            print ' ' * len(key + '=<'), subkey, ': ', subvalue


You could write the assignment in one line but I wouldn't recommend it
(unless you like unreadable code):

def process_log_file(name):
    d = {}
    f = open(name)
    for line in f:
        script, address = process_line(line)
        d[script][address] = d.setdefault(script, {}).setdefault(address,0) + 1
    f.close()
    for (key, value) in d.items():
        print key , '=>'
        for (subkey, subvalue) in value.items():
            print ' ' * len(key + '=<'), subkey, ': ', subvalue



You could separate the printing part in the above function but I didn't
do that because the format is very specific.


   Karl
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