Dick Moores wrote:
> At 06:49 AM 8/6/2007, Kent Johnson wrote:
>
>> Dick Moores wrote:
>>
>>> http://www.rcblue.com/Python/changeMaker_revised_for_US_denominations.py
>>> I'm still working at Python--been at it a while--and thought the
>>> script was ingenious. Do the Tutors agree? Or is it just
>>> run-of-the-mill programming? Could it have been more simply written?
>>>
>> I don't find it either ingenious or well-written. The algorithm is
>> the same one you would use to count out an amount by hand so it
>> doesn't seem so unusual. IMO the code relies too much on indices. If
>> you rewrite it using a dict (or, even better, defaultdict(int)) for
>> coinCount, there is no need for indices at all. Even with coinCount
>> as a list, it could be better written.
>>
>> coinCount = []
>> for d in denominations:
>> coinCount.append(0)
>>
>> =>
>>
>> coinCount = [0] * ndenominations
>>
>>
>> The main loop could be
>> for deno in range(ndenominations):
>> if not remaining:
>> break
>>
>> or
>> for i, deno in enumerate(denominations):
>> # i is now the index, deno is the actual denomination
>>
>>
>> but I would write it this way and avoid the use of the index completely:
>>
>>
> >from collections import defaultdict
>
>> coinCount = defaultdict(int)
>> remaining = change
>>
>> # Loop until either we have given all the change or we have
>> # run out of coin denominations to check.
>> for deno in denominations:
>> if not remaining:
>> break
>>
>> # For one denomination, count out coins of that denomination
>> # as long as the remaining amount is greater than the denomination
>> # amount.
>>
>> while remaining >= deno:
>> coinCount[deno] += 1
>> print "remaining =", remaining
>> remaining -= deno
>>
>> # Report the results.
>> print "Your change is $%.02f"% (float(change) / CPD)
>> for deno in denominations:
>> if coinCount[deno] > 0:
>> if deno >= 100:
>> print "$%d bills:\t" % (deno / CPD), coinCount[deno]
>> else:
>> print "%d-cent coins:\t" % (deno), coinCount[deno]
>>
>>
>> Kent
>>
>
> Thanks Kent!
>
> Here's what I have after incorporating your suggestions:
>
> =================================
> #!/usr/bin/env python
> #coding=utf-8
> from collections import defaultdict
>
> CPD = 100
> cost = int(CPD * float(raw_input("Enter the cost: ")))
> tend = int(CPD * float(raw_input("Enter the tendered amount: ")))
>
> # Calculate the change.
> change = tend - cost
>
> coinCount = defaultdict(int)
> print coinCount
> remaining = change
> denominations = (2000, 1000, 500, 100, 50, 25, 10, 5, 1)
>
> # Loop until either we have given all the change or we have
> # run out of coin denominations to check.
> for deno in denominations:
> if not remaining:
> break
>
>
> # For one denomination, count out coins of that denomination
> # as long as the remaining amount is greater than the denomination
> # amount.
>
>
> while remaining >= deno:
> coinCount[deno] += 1
> remaining -= deno
>
>
Try something like:
def makechange( amount, denominations ):
coins = {}
for d in denominations:
coins[d] = int( amount/d )
amount = amount%d
return coins
> # Report the results.
> print "Your change is $%.02f"% (float(change) / CPD)
> for deno in denominations:
> if coinCount[deno] > 0:
> if deno >= 100:
> print "$%d bills:\t" % (deno / CPD), coinCount[deno]
> else:
> print "%d-cent coins:\t" % (deno), coinCount[deno]
> ========================================
>
> Gotta say though, I still don't understand how the defaultdict works here.
>
> Dick
>
>
>
> _______________________________________________
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
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