Format multiple date formats in one columns using lubridate

Question

Sometimes I am given data sets that has two different date formats but common variables that have to been joined into one dataframe. Over the years, I\'ve tried various solu

Answer 1

parse_date_time of lubridate package can help format multiple date formats in one go.

Syntax:

df$date = parse_date_time(df$date, c(format1, format2, format3))

You need to specify all the possible format types.

Since lubridate has some difficulty understanding (correctly) some format types, you need to make custom format.

In the help section , you will find the below illustration. You can recreate it to suit your requirement.

## ** how to use `select_formats` argument **
## By default %Y has precedence:
parse_date_time(c("27-09-13", "27-09-2013"), "dmy")
## [1] "13-09-27 UTC"   "2013-09-27 UTC"

## to give priority to %y format, define your own select_format function:

my_select <-   function(trained){
   n_fmts <- nchar(gsub("[^%]", "", names(trained))) + grepl("%y", names(trained))*1.5
   names(trained[ which.max(n_fmts) ])
}

parse_date_time(c("27-09-13", "27-09-2013"), "dmy", select_formats = my_select)
## '[1] "2013-09-27 UTC" "2013-09-27 UTC"

Answer 2

From the help on parse_date_time:

## ** how to use select_formats **
## By default %Y has precedence:
parse_date_time(c("27-09-13", "27-09-2013"), "dmy")
## [1] "13-09-27 UTC"   "2013-09-27 UTC"

## to give priority to %y format, define your own select_format function:

my_select <-   function(trained){
  n_fmts <- nchar(gsub("[^%]", "", names(trained))) + grepl("%y",     names(trained))*1.5
  names(trained[ which.max(n_fmts) ])
}

parse_date_time(c("27-09-13", "27-09-2013"), "dmy", select_formats = my_select)
## '[1] "2013-09-27 UTC" "2013-09-27 UTC"