python 推导式

names = ['Tom','Billy','Jefferson','Andrew','Wesley','Steven',
         'Joe','Alice','Jill','Ana','Wendy','Jennifer','Sherry','Eva']
names1=[] # 声明空列表
names2=[]
for i in names:
    if len(i)>4:
        names1.append(i)
print(names1)
for i in names:
    if len(i)<=5:
        names2.append(i.upper())
print(names2)

#列推导式
names11 = [i for i in names if len(i)>4]
names12 = [i.upper() for i in names if len(i)<=5]
print(names11)
print(names12)

m = [[1,2,3],[4,5,6],[7,8,9]]
n = [[2,2,2],[3,3,3],[4,4,4]]
for i in range(0,3):
    for j in range(0,3):
        print(m[i][j]+n[i][j])
#列推导式
sum1 =[m[i][j]+n[i][j] for i in range(3) for j in range(3)]
print(sum1)

字典推导式：