Python-2D lists!

Please do not import any fancy functions..this is only an intro class and we haven't gotten that far yet

Write a function invert(grid) that takes an existing 2-D list of 0s and 1s and inverts it changing all 0 values to 1, and changing all 1 values to 0. Important notes: Unlike the other functions that you wrote for this problem, this function should not create and return a new 2-D list. Rather, it should modify the internals of the existing list. Unlike the other functions that you wrote for this problem, this function should not have a return statement, because it doesnt need one! Thats because its parameter grid gets a copy of the reference to the original 2-D list, and thus any changes that it makes to the internals of that list will still be visible after the function returns. The loops in this function need to loop over all of the cells in the grid, not just the inner ones. For example:

>>> grid = diagonal_grid(5, 5)

>>> print_grid(grid)

10000

01000

00100

00010

00001

>>> invert(grid)

>>> print_grid(grid)

01111

10111

11011

11101

11110

Heres another example that should help to reinforce your understanding of references:

>>> grid1 = inner_grid(5, 5)

>>> print_grid(grid1)

00000

01110

01110

01110

00000

>>> grid2 = grid1

>>> grid3 = grid1[:]

>>> invert(grid1)

>>> print_grid(grid1)

11111

10001

10001

10001

11111

This is what I have from previous problems:

import random

def create_grid(height, width): """ creates and returns a 2-D list of 0s with the specified dimensions. inputs: height and width are non-negative integers """ grid = [] for r in range(height): row = [0] * width # a row containing width 0s grid += [row]

return grid

def print_grid(grid): """ prints the 2-D list specified by grid in 2-D form, with each row on its own line, and nothing between values. input: grid is a 2-D list. We assume that all of the cell values are integers between 0 and 9. """ height = len(grid) width = len(grid[0]) for r in range(height): for c in range(width): print(grid[r][c], end='') # print nothing between values print() # at end of row, go to next line

def diagonal_grid(height, width): """ creates and returns a height x width grid in which the cells on the diagonal are set to 1, and all other cells are 0. inputs: height and width are non-negative integers """ grid = create_grid(height, width) # initially all 0s

for r in range(height): for c in range(width): if r == c: grid[r][c] = 1

return grid #part 1 def inner_grid(height,width): """creates and returns a 2-D list of height rows and width columns in which the "" """ grid=create_grid(height,width)

for r in range(1,height-1): for c in range(1,width-1): if r>0 and r0 and r

return grid

def print_grid(grid): """ prints the 2-D list specified by grid in 2-D form, with each row on its own line, and nothing between values. input: grid is a 2-D list. We assume that all of the cell values are integers between 0 and 9. """ height = len(grid) width = len(grid[0]) for r in range(height): for c in range(width): print(grid[r][c], end='') # print nothing between values print() # at end of row, go to next line def create_new_grid(height,width): """creates a new grid """ new_grid=[] for r in range(height): row = [0] * width # a row containing width 0s new_grid += [row] return new_grid

def print_new_grid(grid): """ prints the 2-D list specified by grid in 2-D form, with each row on its own line, and nothing between values. input: grid is a 2-D list. We assume that all of the cell values are integers between 0 and 9. """ height = len(new_grid) width = len(new_grid[0]) for r in range(height): for c in range(width): print(new_grid[r][c], end='') # print nothing between values print() # at end of row, go to next line def copy(grid): """creates and returns a deep copy of grid, a new, separate 2-D list that has the same dimensions and cell values as grid """ new_grid=[] height = len(grid) width = len(grid[0]) new_grid=create_new_grid(height,width) for r in range(height): for c in range(width): new_grid[r][c]=grid[r][c] return new_grid