Problem with arrays

[Python567]

I want to have four players in an array. Every array has the same variables how can I do that? It‘s my first time to use arrays so I don‘t know how to use them.

[bennr01]

I think you may be confusing a few different datatypes here, so I'll try to explain some approaches for your problem.

First of, Python does not really have something like arrays. Usually, when one wants to use something akin to an array in Python, one uses a list instead. The main difference between a list and an array is that usually arrays are fixed size and often fixed type also while Python lists can have any required size and mixed types of elements. However, you wrote "same variables", so lists may not be what you are looking for. Still, heres a short tutorial for lists:

# create a list
l = []  # alternatively, use "l = list()"
# add an element to a list
l.append(1)
# get the size of the list
print(len(l))
# get the first element (index is 0 as indexes start with 0)
print(l[0])  # prints "1"
# remove the first element
del l[0]  # alternatively, use "l.pop(0)", which also returns the element

Now let's take a look at how lists could be used for your problem:

# number of players
num_players = 4
# number of variables each player has
num_vars = 10

# initiate a two-dimensional list with all players or variables
# a two-dimensional list is a list of lists. In this case, all "variables" will be initialized as None.
players = [[None] * num_vars] * num_players

# set 2nd variable for player 3 to 12. Remember that indexes start at 0
players[2][1] = 12
# get 2nd variable for player 3
print(players[2][1])  # prints "12"

# ============= alternative =============
# using math, we can do this a bit more efficient using 1-dimensional lists

# number of players
num_players = 4
# number of variables each player has
num_vars = 10

# initiate a one-dimensional list with all players or variables
players = [None] * num_vars * num_players
# now we can access a variable by using index = (player_index * num_vars + var_index)

# set 2nd variable for player 3 to 12. Remember that indexes start at 0
players[2 * num_vars + 1] = 12
# get 2nd variable for player 3
print(2 * num_vars + 1)  # prints "12"

However, as I said before, lists aren't a good solution for this. Let's take a look at another datastructure, the dict. A dict is a mapping of key-value pairs. Think of it like a dictionary, where each word you look up (in this case the key) has some associated words (the value). Here is an example of a dict usage:

d = {}  # alternatively, use "d = dict()"
# set a key to a value
d["name"] = "bennr01"
# get the number of defined keys in a dict
print(len(d))  # prints "1"
# get a value for a key
print(d["name]")  # prints "bennr01"
# remove a key-value pair
del d["name"]

Using dicts, you can refer to the variables using names. Here's how to use it for your problem:

players = []
# create a player here
player_1 = dict(name="Player 1", score=0)
players.apend(player_1)

# set the score for the first player (again, index 0)
players[0]["score"] = 100
# get the score for the first player
print(players[0]["score"])  # prints "100"

# ============= alternative ==============
# instead of using a list for all players, you could also use a dict

players = {}  # <-- see the difference
# create a player here
player_1 = dict(name="Player 1", score=0)
players[1] = player_1

# set the score for the first player. As we are using a dict, we do not need to start with 0. We can even use strings
players["pl_1"]["score"] = 100
# get the score for the first player
print(players["pl_1"]["score"])  # prints "100"

Still, what you should be looking into are classes. Classes can have attributes and methods. As a tutorial would take too long, here is how you would use them:

class Player(object):
    """This class represents a player"""
    def __init__(self, name):
        self.name = name
        self.score = 0

    def increment_score(self):
        """Increment the score by 1. This is an example for a method."""
        self.score += 1

players = []
# create a player
player = Player("bennr01")
players.append(player)
# get the name
print(players[0].name)  # prints "bennr01"
# increase score
players[0].increment_score()
# print score
print(players[0].score)  # prints "1"

You can of course combine this with lists and dicts as needed.

[Python567]

@bennr01 thanks for your great answer, I think that is that what I need for my program.

[madivad]

@bennr01 That is a brilliant and well constructed reply. Great work.