08、迭代器

'''
可迭代对象:可以直接作用于for循环的对象统称为可迭代对象

(Iterable),可以用isinstance()去判断一个对象是否是Iterable对象

可以直接作用于for的数据类型一般分两种:
1、集合数据类型,如list,tuple,dict,set,string

2、是generator,包括生成器和带yield的generator function

'''

from collections import Iterable

print(isinstance([],Iterable))
print(isinstance((),Iterable))
print(isinstance({},Iterable))
print(isinstance("",Iterable))
print(isinstance((x for x in range(10)),Iterable))
print(isinstance(1,Iterable))


'''
迭代器:不但可以作用于for循环,还可以被next()函数不断调用并返回下一个值,直到最后跑出一个stopIteration错误表示无法继续返回下一个值

可以被next()函数调用并不断返回下一个值的对象称为迭代器(Iterator对象)

可以使用isinstance()函数判断一个对象是否是Iterator对象


'''
print("xxxx")


from collections import Iterator

print(isinstance([],Iterator))
print(isinstance((),Iterator))
print(isinstance({},Iterator))
print(isinstance("",Iterator))
print(isinstance((x for x in range(10)),Iterator))

'''
l = (x for x in range(5))
print(next(l))
print(next(l))
print(next(l))
print(next(l))
print(next(l))
print(next(l))

'''


l = (x for x in [23,34,5,6,7])
print(next(l))
print(next(l))
print(next(l))
print(next(l))
print(next(l))
#print(next(l))


#转成Iterator对象

a = iter([1,2,3,4,5])
print(next(a))
print(next(a))
print(next(a))
print(next(a))
print(next(a))




-------------------------

'''

endstr = "end"

str = ""

for line in iter(input,endstr):
str += line + "\n"


print(str)

'''

示例1:输入一个字符,看出现几次

w = input()

d = {} #word次数

str = "ssss aa bb cc aa ssss bb cc"

l = str.split(" ")

print(l)

for v in l:
c =d.get(v)
if c == None:
d[v] = 1
else:
d[v] += 1
print(d)

print(d[w])

#1、以空格切割字符串
#2、循环处理列表中的每个元素
#3、以元素当做key去一个字典中提取数据
#4、如果没有提取到,就以该元素作为key,1作为value存进字典
#5、如果提取到,将对应的key的value修改,值加1
#6、根据输入的字符串当做key再去字典取整



#示例二,时间下一秒

timeStr = input()

timeList = timeStr.split(":")

h = int(timeList[0])
m = int(timeList[1])
s = int(timeList[2])

s += 1

if s == 60:
m += 1
s = 0
if m == 60:
h += 1
m = 0
if h == 24:
h = 0
print("%.2d:%.2d:%.2d" % (h, m, s))








posted @ 2020-02-18 14:47  步行-天下  阅读(13)  评论(0)    收藏  举报