How to Format the Date values in R Programming

The Date Values in R Programming
Dates are represented as the number of days since 1970-01-01, with negative values for earlier dates.
# use as.Date( ) to convert strings to dates 

> mydates <- as.Date(c("2007-06-22", "2004-02-13"))
> mydates
[1] "2007-06-22" "2004-02-13"

> typeof(mydates)
[1] "double"
> class(mydates)
[1] "Date"

# number of days between 6/22/07 and 2/13/04
> days <- mydates[1] - mydates[2]
> daysTime difference of 1225 days

Sys.Date( ) returns today's date.
> Sys.Date( )
[1] "2018-11-05"

date() returns the current date and time.
> date()
[1] "Mon Nov 05 22:36:00 2018"
The following symbols can be used with the format( ) function to print dates.

Formatting the Date using the Format() Function :
> mydate<-Sys.Date()
> mydate
[1] "2018-11-05"

> format(mydate,"%m/%d/%Y")
[1] "11/05/2018"
> format(mydate,"%B %d %Y")[1] "November 05 2018"

> typeof(mydate)
[1] "double"
> class(mydate)
[1] "Date"

Date Conversion : Character to Date :
You can use the as.Date( ) function to convert character data to dates.
The format is as.Date(x, "format"), where x is the character data and format gives the appropriate format.

> strDates <- c("15/05/1965", "25/08/1975")
> strDates[1] "15/05/1965" "25/08/1975"

> typeof(strDates)
[1] "character"
> class(strDates)
[1] "character"

# reading the Strings of the dates in format 'dd/mm/yyyy' and converting them to date format.
> dates <- as.Date(strDates, "%d/%m/%Y")
> dates[1] "1965-05-15" "1975-08-25"

> typeof(dates)
[1] "double"
> class(dates)
[1] "Date"

By default R system convert to the ''yyyy-mm-dd'' format after reading.

#Converting date to the format 'mm/dd/yyyy'
> dates <- format(dates, "%m/%d/%Y")
after formatting the "dates" variable to a desired date format, it will be converted to string again.
> dates
[1] "05/15/1965" "08/25/1975"
> typeof(dates)
[1] "character"
> class(dates)
[1] "character"
Converting dates to Character data :
We can convert dates variable to character data using the as.Character( ) function.
strDates <- as.character(dates)

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