Python Two-Dimensional List Processing

Question

loopCount = 0
candidateName = input("Please input the candidates name or type 'DONE' when finished:")
votes = []
while candidateName != "DONE":
     departmentName = input("Please input the department that submitted votes for this candidate:")
     numberOfVotes = input("Please input the number of votes for this candidate:")
     votes.append([])
     votes[loopCount].append(candidateName)
     votes[loopCount].append(departmentName)
     votes[loopCount].append(numberOfVotes)
     print(votes[loopCount])
     loopCount = loopCount + 1
     candidateName = input("Please input the candidates name or type 'DONE' when finished:")

print(votes)

sum = 0
for i in range(0,len(votes)):

This is my code I currently have. I believe what I need done can be done with a for loop. What I'm trying to do is cycle through the list, and add total up each candidate's vote count. Of course, if a candidate has a matching name I would need it to be correctly allocated. If anyone can please just point in the right direction on how I can process a list in this fashion. The multidimensional list is what's throwing me off. Any tips or advice at all would be appreciated. Thank you.

Answer 1

So, what you are looking for is a key,value structure your data such as a python dictionary. Since this is two dimensional (candidate name and department name) you need a nested dictionary.

Python does not allow autovification like perl, so you want to use defaultdict to automatically allow you to use the nested structure like a dictionary.

Here is a refactored version:

from collections import defaultdict
candidates_and_votes = defaultdict(dict)
while True:
     candidateName = input("Please input the candidates name or type 'DONE' when finished:")
     if candidateName == 'DONE':
         break
     departmentName = input("Please input the department that submitted votes for this candidate:")
     numberOfVotes = input("Please input the number of votes for this candidate:")
     candidates_and_votes[candidateName][departmentName] = numberOfVotes

for candidate, department in candidates_and_votes.items():
    total = 0
    print('Candidate Name {}'.format(candidate))
    for dep_name, number in department.items():
        print('  Dep {}. total {}'.format(dep_name, number))
        total += int(number)
    print('     Total Votes = {}'.format(total))

Answer 2

My take. There are fancier ways, but it works

totalvotes = {}
for i in range(0,len(votes)):
     if not votes[i][0] in totalvotes:
          totalvotes[votes[i][0]] = 0
     totalvotes[votes[i][0]] = totalvotes[votes[i][0]]+int(votes[i][2])
print(totalvotes)

or more compact

totalvotes = {}
for vote in votes:
    totalvotes[vote[0]] = totalvotes[vote[0]]+int(vote[2]) if vote[0] in totalvotes else int(vote[2])  
print(totalvotes)

The freaky one-liner:

print([(gk,sum([int(v[2]) for v in gv] )) for gk, gv in itertools.groupby( sorted(votes,key=lambda x:x[0]),lambda x: x[0])])

Answer 3

I would use python dictionary. Modify your code as needed.

votes = [['a','d',3],['b','d',3],['a','d',2]]

unique_names_list = {}
for ballot in votes:
    name = ballot[0]
    department = ballot[1]
    votes = ballot[2]

    name_depart = name + '-' + department

    if name_depart not in unique_names_list.keys():
        unique_names_list[name_depart] = votes
    else:
        unique_names_list[name_depart] = unique_names_list[name_depart] + votes

Answer 4

You would just need to process the results that your code is currently collecting. One way to do that would be like this:

canidates = []
loopCount = 0
candidateName = input("Please input the candidates name or type 'DONE' when finished:")
votes = []
while candidateName != "DONE":
     departmentName = input("Please input the department that submitted votes for this candidate:")
     numberOfVotes = input("Please input the number of votes for this candidate:")
     votes.append([])
     votes[loopCount].append(candidateName)
     votes[loopCount].append(departmentName)
     votes[loopCount].append(numberOfVotes)
     print(votes[loopCount])
     loopCount = loopCount + 1
     candidateName = input("Please input the candidates name or type 'DONE' when finished:")

results = []

#Tally the votes
for v in votes:
    if v[0] in canidates:
        #need to add these votes to an existing canidate.
        for x in results:
            #goes through each record in results and adds the record to it.
            if x[0] == v[0]:
                x[1] = x[1] + ", " + v[1]
                x[2] = x[2] + int(v[2])
    else:
        #need to create a new record for the canidate.
        canidates.append(v[0])
        results.append([v[0],v[1],int(v[2])])


#Display the results
print ("Vote Results:")
for x in results:
    print ("name: " + x[0])
    print ("Departments: " + x[1])
    print ("Votes Total: " + str(x[2]))

So what you would do is go through and combine the entries when there are multiple entries for the same canidate name.