各种推导式

Posted 2021-01-02 hhsh

# 列表推导
# l = [‘鸡蛋%s‘ %i for i in range(10)]
# print(l)

# l = []
# for i in range(10):
#     l.append(‘鸡蛋%s‘ %i)
# print(l)

#生成器表达式，括号不一样，且返回值不一样
# g = (i for i in range(10))
# print(g)                          #生成器
# for i in g:
#     print(i)

# g1 = (i*i for i in range(10))
# print(list(g1))                  #强制转换为list，占内存，不推荐


# 字典推导式
# 例一：将一个字典的key和value对调
# mcase = {‘a‘: 10, ‘b‘: 34}
# mcase_frequency = {mcase[k]:k for k in mcase}
# print(mcase_frequency)

#集合推导式
#将列表去重
# s = {x*x for x in [1,-1,2]}
# s1 =list(s)
# print(s1)