require(lubridate)
# expected to return "2019"
format_date("2019")
# expected to return "20APR2019"
format_date("2019-04-20")
# expected to return ""
format_date("")
# expected to return "18JUN2019"
format_date("2019-06-18T10:32")
# expected to return "APR2019"
format_date("2019-04")
Run the code above in your browser using DataLab