Python Yield语句似乎没有从其中断处继续。
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我必须忽略明显的东西，但是我无法终生弄清楚为什么这个yield语句不能连续给我一个比上一个晚15分钟的新datetime值。 gettime函数的行为更像是“返回”而不是“ yields”的函数。
import datetime
#function that continually adds 15 minutes to a datetime object
def gettime(caldate):
while True:
yield caldate
caldate += datetime.timedelta(minutes=15)
#initialize a datetime object
nextdate = datetime.datetime(2011, 8, 22, 11,0,0,0)
#call gettime function 25 times.
for i in range(0,25):
print gettime(nextdate).next()
#output feels like it should be a series of incrementing datetime values 15 minutes apart.
#in actuality, the same result namely:
#2011-08-22 11:00:00
#happens 25 times.
没有找到相关结果
已邀请:
3 个回复
峨躬坎抬焚
dates = gettime(nextdate) for i in range(0, 25): print dates.next() # note that you\'re not initializing it each time here # just calling next()要记住的重要一点是，当我们看待我的对象时，s的函数实际上会返回一个生成器：您可以反复调用获得下一个值。每次执行循环时，您都在创建一个全新的生成器，并从中获取下一个（在本例中为第一个）值。痰降锭骂奸
from itertools import islice import datetime #generator that continually adds 15 minutes to a datetime object def gettime(caldate): while True: yield caldate caldate += datetime.timedelta(minutes=15) #initialize a datetime object nextdate = datetime.datetime(2011, 8, 22, 11,0,0,0) #call gettime function 25 times. for the_date in islice(gettime(nextdate),0,25): print the_datefrom itertools import islice, count import datetime #initialize a datetime object nextdate = datetime.datetime(2011, 8, 22, 11,0,0,0) #generator expression that continually adds 15 minutes to a datetime object gettime = (nextdate+datetime.timedelta(minutes=15*i) for i in count()) #call gettime function 25 times. for the_date in islice(gettime,0,25): print the_date届甸衬丝蚕
但是您可能只想列出。