pandas 的日期时间将星期日设置为一周的第一天 [英] pandas datetime set Sunday as first day of the week

问题描述

我有一个带有一系列日期(所有星期日)的熊猫数据框:

I've got a dataframe of pandas with a series of dates (all Sundays) like this:

Date        Year    Week
2011-01-02  2011    52
2011-01-23  2011    3
2011-01-23  2011    3
2011-01-30  2011    4
2011-01-30  2011    4

一周是由 df ['Date'].dt.week 给出的，而我想要的是将周日设置为一周的第一天，因此我可以得到:

The week is given by df['Date'].dt.week, and what I want is set Sundays as the first day of the week, so I can get:

Date        Year    Week
2011-01-02  2011    1
2011-01-23  2011    4
2011-01-23  2011    4
2011-01-30  2011    5
2011-01-30  2011    5

如何以最简单的方式做到这一点?

How can I do that in the simplest way?

P.S.我没有提到这个数据集中有很多年.因此，在极少数情况下，一年中的最后一天是星期日，除了明年1月的第一周，我想获得今年的第53周

P.S. I have failed to mention that there're multiple years in this dataset. So for rare occasions there'll be the last day of the year is Sunday, I would like to get The 53rd week of this year other than The 1st week of next year.

推荐答案

您可以使用 dayofweek 来获取.

date = pd.DatetimeIndex(start='2011-01-02', end='2011-12-31',freq='D')
df = pd.DataFrame([date,date.year,date.week,date.dayofweek])
df = df.T
df.columns=['date','year','week','dayofweek']
df['newweek'] = 0
df.loc[df['dayofweek']==6, 'newweek'] = 1
df['newweek'] = df['newweek'].cumsum()

如果您有很多年，那么可以对datetimeindex进行滚动操作.

If you have multiple years, than do a rolling operation on the datetimeindex.

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