Simple exercise

[Mark Lawrence]

On 11/03/2016 00:05, BartC wrote:
> On 10/03/2016 09:02, Rodrick Brown wrote:
>>> From the following input
>>
>> 9
>> BANANA FRIES 12
>> POTATO CHIPS 30
>> APPLE JUICE 10
>> CANDY 5
>> APPLE JUICE 10
>> CANDY 5
>> CANDY 5
>> CANDY 5
>> POTATO CHIPS 30
>>
>> I'm expecting the following output
>> BANANA FRIES 12
>> POTATO CHIPS 60
>> APPLE JUICE 20
>> CANDY 20
>
>
> Here's a rather un-Pythonic and clunky version. But it gives the
> expected results. (I've dispensed with file input, but that can easily
> be added back.)
>
> def last(a):
>      return a[-1]
>
> def init(a):                 # all except last element
>      return a[0:len(a)-1]

What is wrong with a[0:1] ?

>
> data =["BANANA FRIES 12",    # 1+ items/line, last must be numeric
>         "POTATO CHIPS 30",
>         "APPLE JUICE 10",
>         "CANDY 5",
>         "APPLE JUICE 10",
>         "CANDY 5",
>         "CANDY 5",
>         "CANDY 5",
>         "POTATO CHIPS 30"]
>
> names  = []                        # serve as key/value sets
> totals = []
>
> for line in data:                  # banana fries 12
>      parts = line.split(" ")        # ['banana','fries','12']
>      value = int(last(parts))       # 12
>      name  =  " ".join(init(parts)) # 'banana fries'
>
>      try:
>          n = names.index(name)      # update existing entry
>          totals[n] += value
>      except:

Never use a bare except.  Better still, use an appropriate collection 
rather than two lists.  Off of the top of my head a counter or a 
defaultdict.

>          names.append(name)         # new entry
>          totals.append(value)
>
> for i in range(len(names)):
>      print (names[i],totals[i])
>

Always a code smell when range() and len() are combined.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence