一列有日期时间和日期，如何将日期时间转换为日期，并保持日期

Question

I want to convert the Infection_time(date time) to Infection_date (date), my code is as followings:

    Infection_HAI1$Infected_date<-format(as.POSIXct(strptime(Infection_HAI1$INFECTED_TIME,
"%Y-%m-%d %H:%M:%S",tz="")) ,
format = "%Y-%m-%d")

I expect the 2015-01-28 keep same, however, the actual output is NA

INFECTED_TIME         Infected_date
2014-12-22 23:59:59   2014-12-22 
2015-01-28            2015-01-28

Answer 1

The as.Date function should work, as in

> as.Date('2014-12-22 23:59:59')
[1] "2014-12-22"