日期功能不起作用

Question

I have a huge data set I am working with. Some of the months are in the format 01/01/2010 and others are 1/1/2010 .

When I run as.Date(Dates, format="%y/%d/%m") all of the latter dates change the year to 2020. What is going on here?

Answer 1

Your format statement is not correct. Try this:

d1 <- "01/01/2010"
d2 <- "1/1/2010"
> as.Date(d1, format='%d/%m/%Y')
#[1] "2010-01-01"
> as.Date(d2, format='%d/%m/%Y')
#[1] "2010-01-01"

For dates with different formats of the year, the lubridate package can be used:

library(lubridate)
d1 <- "1/1/10"
d2 <- "01/01/2010"
parse_date_time(d1, "dmy")
#[1] "2010-01-01 UTC"
parse_date_time(d2, "dmy")
#[1] "2010-01-01 UTC"