python_推导式

• 列表推导式

　　目的：方便的生成一个列表

　　格式：

　　　　v1 = [i for i in 可迭代对象 ]

　　　　v2 = [i for i in 可迭代对象 if条件]#条件为True菜进行append

v1 = [i for i in 'alex']
# 变量 = [for循环的变量 for循环一个可迭代的对象]
v2 = [i+100 for i in range(10)]
v3 = [100 for i in range(10)]
v4 = [99 if i > 5 else 66 for i in range(10)]
def func():
    print(123)
v5 = [func for i in range(10)]
v6 = [lambda :i for i in range(10)]
v7 = [lambda x:x*i for i in range(10)]
print(v1)
print(v2)
print(v3)
print(v4)
print(v5)
print(v6[9]())
print(v7[0](2))

# 筛选功能
v8 = [i for i in range(10) if i >5]
print(v8)

• 集合推导式

　　格式：v1 = {i for i in 可迭代对象} 

v8 = {i for i in range(10) if i >5}
print(v8)

• 字典推导式

　　格式：v1 = {'k'+str(i):i for i in range(10)} 

v1 = {'k'+str(i):i for i in range(10)}
print(v1)