[Tutor] Need help with dict.calculation

[Sean 'Shaleh' Perry]

On 18-Jan-2002 Eve Kotyk wrote:
> In the script below I would like to add up the totals for each item into
> one final total.  So far I haven't come up with anything.  Help.
> 

I have been writing a program at work which reads a log and keeps a running
count of machine reboots per machine.  A nifty way to handle the increment is
the get() method of dictionaries.

dict[key] = dict.get(key, 0) + 1

OK, so this doesn't help directly, but I thought I would share.  Onto the real
help.

Another useful python function is 'reduce'.  reduce takes a list and runs a
function on each item in the list plus a running variable.

from above I have:

import operator
count = reduce(operator.add, dict.values())
print "Total reboot count for all machines was " + count

What reduce does is more clear if I show you what operator.add looks like:

def add(x, y):
    return x + y

so what the reduce function does internally is basically:

value = 0
for item in list:
    value = function(value, item)
return value

Hope this gives you some glimpses of python's abilities.