如何从Python的Datetime对象中查找工作日名称？

Question

So I just started learning python and tried to make a program that tells you day on a given day. I discovered datetime and tried to use it, but the problem is I am getting key error even though the key is present.

Here's my code:

import datetime

def day_finder(dd,mm,yy):

    tags = { '1' : 'Monday' ,'2' : 'Tuesday' ,'3' : 'Wednesday' ,'4' : 'Thursday' ,'5' : 'Friday' ,'6' : 'Saturday' ,'7' : 'Sunday' }
    return tags[int(datetime.datetime(yy,mm,dd).isoweekday())]


d = int(input("Enter a date"))
m = int(input("Enter a month"))
y = int(input("Enter a year"))

print (day_finder(d,m,y))

Answer 1

You are searching for an int weekday number, but instead you should be checking for the string because the keys in your dictionary are of str type. For example:

>>> tags = { '1' : 'Monday' ,'2' : 'Tuesday' ,'3' : 'Wednesday' ,'4' : 'Thursday' ,'5' : 'Friday' ,'6' : 'Saturday' ,'7' : 'Sunday' }

>>> import datetime
>>> tags[str(datetime.datetime(1990,03,28).isoweekday())]
'Wednesday'

However, you do not need a dict object to get the weekday name based on the key day number. You may get the desired result via using .strftime('%A') on the datetime object as:

>>> datetime.datetime(1990,03,28).strftime("%A")
'Wednesday'

Answer 2

keys in your tags object are str values, however you convert them to int (which they already are) and then try to access value by int value, that's why you get KeyError .

Fix would be convert them to str and everything would work.

return tags[str(datetime.datetime(yy,mm,dd).isoweekday())]

Answer 3

isoweekday returns an integer. The keys of your dictionary are strings.

You don't need to call int on the result as it is already an int - either replace that with str , or use integers as the keys of your dict.

Answer 4

尝试在查询字符串不是整数。

return tags[str(datetime.datetime(yy,mm,dd).isoweekday())]