python_L6

1. tuples:

　　(3) -> 3 but (3,) indicates a tuple -> (3,)　　

2. tuples and lists:

　　tuples:num = (1,2,3)　　(3,)　　不可修改  num(1) = 4  -> ‘error‘

　　lists:num = [1,2,3]　　　[3]　　可以修改   num[1] = 4 -> [1,4,3]

.

## universities

Techs = [‘MIT‘, ‘Cal Tech‘]
Ivys = [‘Harvard‘, ‘Yale‘, ‘Brown‘]

Univs = [Techs, Ivys]
Univs1 = [[‘MIT‘, ‘Cal Tech‘], [‘Harvard‘, ‘Yale‘, ‘Brown‘]]

Techs.append(‘RPI‘)

print(‘Univs = ‘)
print(Univs)
print(‘‘)
print(‘Univs1 =‘)
print(Univs1)

for e in Univs:
    print(‘Univs contains ‘)
    print(e)
    print(‘   which contains‘)
    for u in e:
        print(‘      ‘ + u)