CODEWITHSUNDEEP
python
Chuck0185
Chuck0185

Reputation: 531

What is the best way to loop through object instances in Python?

I am very new to Python so please bear with me if you can. I have created a class called team that has 4 attributes (city, teamname, wins, losses). I've created 5 instances of team (team_1, team_2, team_3, team_4, team_5) and have initialized their attributes. See the code below. I am looking for a way to loop through the instances and produce an output that lists the teams by ascending order of wins. I'm not sure if the best way to do this would be to somehow create a list or dictionary from the instances or if there is a more efficient way to loop through the instances. Again I am extremely green when it comes to Python and would very much appreciate any help I can get. Thank you in advance for your time!

class team:

    def __init__(self, city, teamname, wins, losses):
        self.city = city
        self.teamname = teamname
        self.wins = wins
        self.losses = losses

team_1 = team('Boston','Red Sox', 162, 0)
team_2 = team('New York', 'Yankees', 0, 162)
team_3 = team('Tampa Bay', 'Rays', 80, 82)
team_4 = team('Toronto', 'Blue Jays', 82, 80)
team_5 = team('Baltimore', 'Orioles', 1, 161)

Upvotes: 0

Views: 86

Answers (4)

vlizana
vlizana

Reputation: 3232

You can define the operator < (less than) in a class like this:

class Team:
    def __init__(self, city, teamname, wins, losses):
        self.city = city
        self.teamname = teamname
        self.wins = wins
        self.losses = losses

    def __lt__(self, other):
        return self.wins < other.wins

    def __repr__(self):
        return self.teamname # or what you want to show

This way python knows how to sort a list of objects from this class.

sorted_list = sorted([team_1, team_2, team_3, team_4, team_5])

Also by defining the representation operator python knows what to show when the print function is called upon one of these objects.

Upvotes: 1

Vineeth Sai
Vineeth Sai

Reputation: 3447

As many have mentioned in the comments, Creating a list and iterating through is the most simple way to go about it.

team_list = []
team_list.append(team('Boston','Red Sox', 162, 0))
team_list.append(team('Boston','Red Sox', 162, 0))
team_list.append(team('New York', 'Yankees', 0, 162))
team_list.append(team('Tampa Bay', 'Rays', 80, 82))
team_list.append(team('Toronto', 'Blue Jays', 82, 80))
team_list.append(team('Baltimore', 'Orioles', 1, 161))

# For sorting the teams
sorted_team = sorted(team_list, key=lambda team: team.wins)
print([team.city for team in sorted_team])

Upvotes: 1

Charles Landau
Charles Landau

Reputation: 4265

Python has built in sorting with sorted https://docs.python.org/3/tutorial/datastructures.html#more-on-lists

You can pass it a key. So here we go:

class Team: # Capitalize your class names

    def __init__(self, city, teamname, wins, losses):
        self.city = city
        self.teamname = teamname
        self.wins = wins
        self.losses = losses

team_list = [Team('Boston','Red Sox', 162, 0), 
             Team('New York', 'Yankees', 0, 162),
             Team('Tampa Bay', 'Rays', 80, 82),
             Team('Toronto', 'Blue Jays', 82, 80),
             Team('Baltimore', 'Orioles', 1, 161)]

def sort_key(x):
  return x.wins

teams_sorted = sorted(team_list, key=sort_key)
print([x.city for x in teams_sorted])
# ['New York', 'Baltimore', 'Tampa Bay', 'Toronto', 'Boston']

Upvotes: 1

John Gordon
John Gordon

Reputation: 33275

Create an empty list, then append() each new team object onto the list:

teams = []
teams.append(team('Boston','Red Sox', 162, 0))
teams.append(team('New York', 'Yankees', 0, 162))
teams.append(team('Tampa Bay', 'Rays', 80, 82))
teams.append(team('Toronto', 'Blue Jays', 82, 80))
teams.append(team('Baltimore', 'Orioles', 1, 161))

Upvotes: 0

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