python列表推导式使用

****#**列表推导式******
alist=[]#一般的操作方式
for x in range(30):
    alist.append(x+x)
print(alist)
alist=[x+x for x in range(30)]#使用列表推导式，形式上更加简洁
print(alist)
freshfruit=['banana','apple','oregan']
alist=[]#一般的操作方法
for x in freshfruit:
    alist.append(x.strip())
print(alist)
alist=[x.strip() for x in freshfruit]#使用列表推导式方法
print(alist)
#使用列表推导式实现嵌套列表的平铺
vec=[[1,2,3],[4,5,6],[7,8,9]]#一般的方法
result=[]
for elem in vec:#遍历列表中的子列表
    for num in elem:#遍历子列表里的元素
        result.append(num)
print(result)
vec=[[1,2,3],[4,5,6],[7,8,9]]
x=[num for elem in vec for num in elem]
print(x)

结果输出

[0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58]
[0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58]
['banana', 'apple', 'oregan']
['banana', 'apple', 'oregan']
[1, 2, 3, 4, 5, 6, 7, 8, 9]
[1, 2, 3, 4, 5, 6, 7, 8, 9]