Getting an error with my for loop involving numpy arrays

Question

I'm making a game and I'm getting the error: "IndexError: only integers, slices (:), ellipsis (...), numpy.newaxis (None) and integer or boolean arrays are valid indices."

In the following block of code, play_game is a function that returns a string, and roll_dice is a random array. Basically, I'm trying to get all the strings into an array, so into total_games. However, I can't do this because of this error, which I'm not sure exactly what it means. If someone could clarify what the error means or how I can fix this code it'd be greatly appreciated.

def game_session(num_games=50):
    total_games = np.zeros(num_games)
    for i in total_games:
        total_games[i] = play_game(roll_dice())
    return total_games

Loocid · Accepted Answer · 2019-04-08 01:52:20Z

1

.zeros creates an array of floating point zeros (0.0).

When you do for i in total_games, i will always be 0.0 and obviously total_games[0.0] can't be done for the reason your error message suggets.

I belive what you want is for i in range(len(total_games)) which will iterate through the indicies of total_games, ie 0, 1, 2, 3, ....

answered Apr 8, 2019 at 1:52

Loocid

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5 Comments

Joey Jordan Over a year ago

Doing that fixes it, but now I get an error: could not convert string to float. This is because play_game() returns a string

Loocid Over a year ago

In that case, the answer @Szymon Maszke provided may be more what you need.

Joey Jordan Over a year ago

Ok yea. Only problem with that one is it has to be the size of the parameter num_games and I can't iterate through an empty list.

Szymon Maszke Over a year ago

@JoeyJordan is that what you are after?

Joey Jordan Over a year ago

@SzymonMaszke yea sorry I should've clarified. I need it to be the size of num_games

Szymon Maszke · Accepted Answer · 2019-04-08 02:00:47Z

1

You cannot input string into np.array of type np.float64, as this data structure contains only one type (by default np.float64 as in this example).

What you are after is a normal Python's list, try this code:

def game_session(num_games=50):
    total_games = []
    for _ in range(num_games):
        total_games.append(play_game(roll_dice()))
    return total_games

@Loocid's answer is also right, there are multiple problems with your code.

Actually you can (and probably should) do it more pythonic like this:

def game_session(num_games=50):
    return [play_game(roll_dice()) for _ in range(num_games)]

edited Apr 8, 2019 at 2:00

answered Apr 8, 2019 at 1:52

Szymon Maszke

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