def count_parties(parties):
"""Count the number of parties in a list.
Parameters
----------
parties : list
names of political parties
Returns
-------
number of names in the list
"""
passThere’s more than one way to run an election!
There’s more than one way to run an election!
Prerequisites
-
function definition
-
list operations
Background
Continuing on in the theme of assignment 1, you will implement some Python functions related to different electoral systems. In particular, you will implement functions related to the first-past-the-post system (used to choose representatives in Parliament and Provincial legislatures) as well as ranked voting, used in Canada to decide some mayoral races as well as the leadership contests of many political parties.
Objective
To fully complete this assignment, you will implement five functions:
count_parties-
counts the elements in a list
count_votes-
counts the votes received by each party
first_choices-
counts the first-choice votes for each party in a ranked voting system
remove-
removes a less-preferred party from a list
ranked_ballot-
performs a ranked-ballot election
Some of these functions will be fairly straightforward to implement; others may be more complex and take longer. Their specifications are described below in Details.
Suggestions
We are now reaching the point in the course where we can start to solve real and interesting problems such as this one. This problem is more complex than what we’ve faced before, so start now! You won’t want to leave this assignment for the last minute.
Another suggestion: don’t try to do it all at once! This problem is complex enough that you should solve it a bit at a time:
-
Start by solving part of the problem (e.g., one of the first functions), working through just that part with our problem-solving workflow:
-
Understand the problem (do it by hand a few times)
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Break it into smaller steps (write pseudocode or flowchart)
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Translate your solution into Python code
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Once you’ve solved part of the problem, expand your solution to handle larger and larger chunks of the problem (e.g., implementing multiple functions that work together). Follow the same workflow (understand/break/translate) each time you expand the problem until you have a solution to the whole assignment.
Remember that partial solutions will still earn partial credit. If you can only solve 3/4 of the assignment, you will still earn approximately 3/4 of the marks! It’s much better to earn 75% of the marks for a partial solution than to earn 0% by giving up (or by committing academic misconduct, e.g., letting a classmate tell you how to solve it).
Finally, if you’re not sure what to do, reach out. There are so many people here to help you, so please avail of our support! We won’t tell you the solution, but we will do something even better: ask you the right questions that help you find the solution.
Details
Here are the precise input/output specifications for the five functions I’ve asked you to write. They are described using docstrings, as we’ve talked about in class.
Counting parties
Counting votes
def count_votes(parties, votes):
"""Count the number of votes received by each party.
This function will count the number of votes that each party in the list
For example, if parties=['A', 'B', 'C'] and votes=['A', 'A', 'C', 'A', 'C'],
this function should return [3, 0, 2].
Parameters
----------
parties : list of str
political party names
votes: list of str
votes cast in an electoral district
Returns
-------
list
number of votes received by each party in the district, in the same
order as in the `parties` parameter
"""
passRanked ballot choices
def first_choices(parties, ballots):
"""Determine how many first-choice votes each party received in a
ranked-ballot system.
In ranked-ballot voting, every voter has the opportunity to rank all
candidates, rather than placing an X next to one candidate. This function
examines a list of ballots and determines how many "first-choice" votes
each party received.
Parameters
----------
parties : list
a list of names of parties contesting an election
ballots : list of lists
a list of ballots, where each ballot is a list of party names in order
of one voter's preference
Returns
-------
list
the number of first-choice votes each party received, in the same order
as the list of parties
"""
passRemoving unpopular choices
def remove(needle, haystack):
"""Remove all instances of `needle` from the iterable `haystack`.
This function will return a list that contains all of the values from
`haystack` in the same order that they were presented, but without any
instances of the value in `needle`.
Parameters
----------
needle
value to remove all instances of from the haystack
haystack : iterable
iterable (e.g., list) of values
Returns
-------
list
a new list that contains all of the values from `haystack`
*except* for the value in `needle`
"""
passRanked-ballot voting
def ranked_ballot(parties, ballots):
"""Determine who won an election based on ranked ballot.
In ranked-ballot voting, every voter has the opportunity to rank all
candidates, rather than placing an X next to one candidate. In the first
round of voting, each voter's first choice is counted. If a candidate
achieves 50% of the vote + 1, they win the election. Otherwise, the
candidate with the lowest number of votes is dropped, changing who their
first-choice voters are now voting for. For example, if a voter ranked
party A, then C, then B, and party A is dropped from the ballot, the voter's
ballot will now be C and then B.
This process continues (voting and dropping the candidate/party with the
lowest number of votes) until one candidate/party achieves 50% + 1.
That candidate is then deemed elected.
Parameters
----------
parties : list
a list of names of parties contesting an election
ballots : list of lists
a list of ballots, where each ballot is a list of party names in order
of one voter's preference
Returns
-------
str
the name of the party/candidate who won the race
"""
pass