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rdatedigitsas.date

as.Date returns the day with four digits in R

I am trying to convert a character to date format, but "day" is replaced with 4 digits.

> mydate="20/3/20"
> mydate=as.Date(mydate)
> mydate
[1] "0020-03-20"

This didn't happen a few days ago, only now as I re-run an old script. I don't know if this has to do with me upgrading recently to R version 3.6.3.

I tried to remove the "00" with gsub, but it turns the date back to character again.

> mydate=gsub("00","",mydate)
> class(mydate)
[1] "character"

Does anyone know how I can fix that with mydate remaining as date, or why this happens?

Thank you in advance

Solution

  • The default format for Date class is "%Y-%m-%d" i.e. 4 digit year followed by a dash, followed by two digits, then a dash and two digits. Any other format, we need to specify the format argument in as.Date

    as.Date(mydate, "%d/%m/%y")
#[1] "2020-03-20"

    We need to be very careful with two-digit year as it can lead some strange output. It is better to have 4 digit year