Python IndexError: list assignment index out of range

Question

Can anyone point me to what's wrong?

I got stuck on newGrid.setValue(n[k][0], n[k][1], List[k]) trying to feed the values of each x/y of each coord into a different function, which takes three arguments, x y and value. Value is what is printed in a position on a grid, x & y are the coordinates.

self.listOfRows[x - 1][y - 1] = value 
IndexError: list assignment index out of range

def gridMileage(List):
    x = []
    y = []
    n = []
    k = 0
    best = 0
    while len(List) > 0:
        for i in range(len(List)):
            x = List[i][0]
            y = List[i][1]
            n.append([x,y])
        if x > best:
            best = x
        elif y > best:
            best = y
        newGrid = Grid(best)
        while k < 2:
            newGrid.setValue(n[k][0], n[k][1], List[k])
            k = k + 1
        del List[0]
        del List[1]
        del n[0]
        del n[1]
        newGrid.setValue(n[0], n[0] + 1, math.sqrt((n[0][0] - n[1][0])**2 + (n[0][1] - n[1][1])**2))
        newGrid.setValue(n[1] + 1, n[1], math.sqrt((n[1][0] - n[0][0])**2 + (n[1][1] - n[0][1])**2))
        z = len(newGrid.listOfRows)
        while z > 0:
            print(newGrid.listOfRows[z - 1])
            z = z - 1

class Grid:
    def __init__(self, n):
        self.listOfRows = []
        for i in range(n):
            row = []
            for j in range(n):
                row.append('*')
            self.listOfRows.append(row)

    def setValue (self, x, y, value):
        self.listOfRows[x - 1][y - 1] = value

Michael0x2a · Accepted Answer · 2013-10-18 14:19:17Z

2

The problem is that ultimately, you appear to be feeding in a list index that is either too small, or too large.

According to the error message, the problematic piece of code is self.listOfRows[x - 1][y - 1] = value. You call it by doing newGrid.setValue(n[k][0], n[k][1], List[k]). The problem can't be List[k], since that's not what's causing the stacktrace.

Therefore, that means either n[k][0] or n[k][1] is too big for newGrid.listOfRows.

I would double-check your code by adding in print statements before that line to examine those two values, as well as double-checking exactly how large your grid is.

Since the only place you appear to add any values to n is at (I think?):

for i in range(len(List)):
    x = List[i][0]
    y = List[i][1]
    n.append([x,y])

...that implies that the root issue is ultimately with the List variable that you've passed in.

answered Oct 18, 2013 at 14:19

Michael0x2a

65.5k32 gold badges189 silver badges241 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Alex James Over a year ago

Thanks - I found that the error was with when I was determining the size of the grid, I'd used an If-Elif, and the grid had initialized itself to 1*1 - it hadn't checked if the y coord was bigger, so a coord (2, 3) couldn't be passed to the grid.

masterzagh · Accepted Answer · 2013-10-18 14:30:29Z

0

self.listOfRows[x - 1][y - 1] = value

what if x and y are 0 that gives you

self.listOfRows[-1][-1] = value

it doesnt exist

edited Oct 18, 2013 at 14:30

answered Oct 18, 2013 at 14:11

masterzagh

11 bronze badge

2 Comments

Alex James Over a year ago

self.listOfRows[x][y] = value IndexError: list index out of range

masterzagh Over a year ago

List[i][0] newGrid.setValue(n[k][0], n[k][1], List[k]) you are sending an array into a value?

Collectives™ on Stack Overflow

Python IndexError: list assignment index out of range

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related