Geneste lijsten en iteratie

matrix = [[1,2,3],[4,5,6],[7,8,9]]
print(matrix[1][2])

matrix = [[1,2],[3,4]]
for row in matrix:
    print(row)

matrix = [[1,2],[3,4]]
for row in matrix:
    for val in row:
        print(val, end=' ')

matrix = [[1,2],[3,4]]
flat = [x for row in matrix for x in row]
print(flat)

grid = [[0]*3 for _ in range(3)]
grid[0][0] = 1
print(grid)

bad = [[0]*3]*3
bad[0][0] = 9
print(bad)  # all rows changed!

names = ['Alice', 'Bob']
scores = [90, 85]
for n, s in zip(names, scores):
    print(n, s)

matrix = [[1,2],[3,4]]
for i, row in enumerate(matrix):
    for j, val in enumerate(row):
        print(f'[{i}][{j}]={val}')

data = [['Bob',85],['Alice',90],['Charlie',78]]
data.sort(key=lambda x: x[1])
print(data)

matrix = [[1,2,3],[4,5,6]]
print(list(zip(*matrix)))