R package to export ICS?

Question

Does anyone know of an R function to export dates and labels to an ics calendar format?

I've googled and searched SO but nothing is obvious, but can't believe someone hasn't already done this...

Answer 1

The iCalendar specification is pretty straightforward. Extending the following after reading that link and keeping it handy as a reference should be trivial (and I use that word deliberately vs lightly):

#' Create a minimal iCalendar VEVENT
#' 
#' @param start,end start and end times of the event. This will be converted to
#'        GMT from whatever time zone it currently is.
#' @param summary a summary of the event. This is the "title" you see in calendars.
#' @param domain something that will help the generated UUID be even more unique and
#'        is generally good practice to use your org's domain name
#' @return atomic character vector ready for `writeLines()`
create_ical <- function(start, end, summary, domain="example.com") {
  
  require(uuid, quietly = TRUE, warn.conflicts = FALSE)
  
  sprintf(
    "BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//rstats//NONSGML v1.0//EN
BEGIN:VEVENT
UID:%s@%s
DTSTAMP:%s
DTSTART:%s
DTEND:%s
SUMMARY:%s
END:VEVENT
END:VCALENDAR
", uuid::UUIDgenerate(),
    domain, 
    format(Sys.time(), "%Y%m%dT%H%M%SZ", tz="GMT"), 
    format(start, "%Y%m%dT%H%M%SZ", tz="GMT"), 
    format(end, "%Y%m%dT%H%M%SZ", tz="GMT"), 
    summary
)
  
}

Usage:

create_ical(
  as.POSIXct("2018-01-30 13:00:00", origin="1970-01-01 00:00:00"),
  as.POSIXct("2018-01-30 14:00:00", origin="1970-01-01 00:00:00"),
  "A good description of the event",
  "somedom.org"
) -> ics_event

cat(ics_event)
## BEGIN:VCALENDAR
## VERSION:2.0
## PRODID:-//rstats//NONSGML v1.0//EN
## BEGIN:VEVENT
## UID:[email protected]
## DTSTAMP:20180116T123051Z
## DTSTART:20180130T180000Z
## DTEND:20180130T190000Z
## SUMMARY:A good description of the event
## END:VEVENT
## END:VCALENDAR

writeLines(ics_event, "ics_event.ics")