import os

# list 列表生成式

classmates = ['Michael', 'Bob', 'Tracy']

classmates.append('Admin')

classmates.insert(2, 'Jack')

# classmates.pop()

print(classmates)

print('classmates length : %d' % len(classmates))

print('classmates length :', len(classmates))

# tuple 元组

tupleList = ('Michael', 'Bob', 'Tracy')

print('tupleList length : %d' % len(tupleList))

print([x * x for x in range(1, 11)])

print([x * x for x in range(1, 11) if x % 2 == 0])

print([m + n for m in 'ABC' for n in 'XYZ'])

print([d for d in os.listdir('.')])

L = ['Hello', 'World', 'IBM', 'Apple']

print([x.lower() for x in L])

print([x if x % 2 == 0 else -x for x in range(1, 11)])

L1 = ['Hello', 'World', 18, 'Apple', None]

L2 = [x.lower() for x in L1 if isinstance(x, str)]

print('L2', L2)