[Tutor] Dictionary Issue

[Mark Lawrence]

On 05/08/2015 23:58, Ltc Hotspot wrote:
> Hi Mark,
>
> Address identifies the email address with the maximum  number of sends:
> cwen at iupui.edu.
>
> Secondly, we are missing a count on the number of messages sent by
> cwen at iupui.edu, i.e., 5.
>
> Thirdly, maxval 'none' is not defined on line # 24
>
> Questions: How do we define the value of none for the key maxval and
> retrieve a number count on the number of messages sent by cwen at iupui.edu.
>
>
> NameError:
>
> Traceback (most recent call last)
> C:\Users\vm\Desktop\apps\docs\Python\assignment_9_4_5.py in <module>()
>       22 ## find the greatest number of mail messages.
>       23
> ---> 24 maxval = none
>       25 maxkee = none
>       26 for kee, val in count.items():
>
> NameError: name 'none' is not defined
>
> In [52]: print address
> cwen at iupui.edu
>
> Revised data:
>
>
> ## The program looks for 'From ' lines and takes the second
> ## word of those lines as the person who sent the mail.
>
> fname = raw_input("Enter file name: ")
> handle = open (fname, 'r')
> for line in handle:
>      if line.startswith("From: "):
>          address = line.split()[1]
>
>
> ## The program creates a Python dictionary that maps
> ## the sender's mail address to a count of the number
> ## of times they appear in the file.
>
>          count = dict()
>          for wrd in address:
>              count[wrd]= count.get(wrd,0) +1
>
> ## After the dictionary is produced, the program reads
> ## through the dictionary using a maximum loop to
> ## find the greatest number of mail messages.
>
> maxval = none
> maxkee = none
> for kee, val in count.items():
>      if maxval == none or maxval <val:
>          maxval = val
>          maxkee = kee
>

You can greatly simplify all of the above code if you use a Counter from 
the collections module 
https://docs.python.org/3/library/collections.html#collections.Counter

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

Mark Lawrence