Python TypeError: 'function' object is not subscriptable

Question

What is meaning of the error and where is the mistake? I got the TypeError: 'function' object is not subscriptable for the following line:

row = random.choice(get_the_valid_locations[-2])

here is the get_the_valid_locations function:

def get_the_valid_locations(board):
        valid_locations = []
        for col in range(COLS_OF_BOARD):
            for row in range(ROWS_OF_BOARD):
                if available_square(board, row, col):
                    valid_locations.extend([row, col])
        return valid_locations

get_the_valid_locations[-2] is an int (I checked).

If you need more Code just ask for it the comments!

you're using subscription operator instead of using function calling — Sajid
– Sajid, Commented Jan 9, 2021 at 13:27
it's unclear what -2 is supposed to be. Presumably you want element at index -2 from the list returned by get_the_valid_locations. However you need to call that function and pass argument for board (2D list?). We don't know what object/variable you want to pass for board. — buran
– buran, Commented Jan 9, 2021 at 13:34
@buran you're right that's why I deleted my answer as it is not useful and may mislead. I wonder from where COLS_OF_BOARD and ROWS_OF_BOARD is coming from. Probably global variables? — Sajid
– Sajid, Commented Jan 9, 2021 at 13:42

Seppukki · Accepted Answer · 2021-01-09 13:45:53Z

1

The line that gives the error has a small mistake.
Now you try to take the second to last element of a function, but you I think you to give -2 as an argument to the function.
In that case the line should be:

row = random.choice(get_the_valid_locations(-2))

Then row will contain a random element from the output of your function.

EDIT
A comment (credits: buran) noted that the function requires a 2d array, in that case I think you mean well, but implement it wrong. You want the output to be an array of colums and an array of rows. Your statement would be used to choose a random value of the rows returned by the functions.
You could do it like this:

def get_the_valid_locations(board):
    valid_rows = []
    valid_columns = []
    for col in range(COLS_OF_BOARD):
        for row in range(ROWS_OF_BOARD):
            if available_square(board, row, col):
                valid_rows.append(row)
                valid_columns.append(col)
    return [valid_rows, valid_columns]

usage:

randomRow = random.choice(get_the_valid_locations(board)[0])

or

randomColumn = random.choice(get_the_valid_locations(board)[1])

Note: if you just want a random position on the `board` object, your code is correct, but your call should be:

row = random.choice(get_the_valid_locations(board))

edited Jan 9, 2021 at 13:45

answered Jan 9, 2021 at 13:29

Seppukki

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3 Comments

buran Over a year ago

get_the_valid_locations expects argument for board, most likely 2d list. calling it with board=-2 will cause error.

Cowcake Over a year ago

Yes I think buran is right. Is there a possibility I can put both (board) and (-2) inside?

Seppukki Over a year ago

I made some edits, if they don't cover your problem, try explaining it a bit more

buran · Accepted Answer · 2021-01-09 13:47:45Z

0

assuming board is a name that you want to pass as argument for parameter board and you want just last 2 elements of the list returned from the function:

row = random.choice(get_the_valid_locations(board)[-2:])

This will randomly select one value out 0f the 2 last values.

answered Jan 9, 2021 at 13:47

buran

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Comments

starmandeluxe · Accepted Answer · 2025-01-17 10:05:53Z

0

In my case, this error shows when you accidentally (e.g. made a typo) use brackets instead of parentheses to call your function, e.g.:

def my_func(arg1):
   pass
my_func[arg1] # oops

Solution: simply call the function with parentheses instead:

def my_func(arg1):
   pass
my_func(arg1) # fixed

So similarly, in your case, you should simply change the brackets into parentheses to call your function:

Broken:

get_the_valid_locations[-2] # X

Fixed:

get_the_valid_locations(-2) # O

Just make sure your function is actually expecting an integer. It's unclear what type board is, so I highly recommend that you start using type hints in your function signatures.

answered Jan 17 at 10:05

starmandeluxe

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