Date Formats in R

dateFormats.R

# importing dates:
  dates <- c("05/27/84", "07/07/05")
	betterDates <- as.Date(dates,
		format = "%m/%d/%y") # here you put the format your dates are currently in
	# it will output the ISO standard dates (%Y-%m-%d)

# or:

	dates <- c("May 27 1984", "July 7 2005")
	betterDates <- as.Date(dates,
		format = "%B %d %Y")
  betterDates

	# from Windows Excel:
	dates <- c(30829, 38540)
	betterDates <- as.Date(dates,
		origin = "1899-12-30")
  betterDates

	# from Mac Excel:
	dates <- c(29367, 37078)
	betterDates <- as.Date(dates,
		origin = "1904-01-01")
  betterDates

# using dates:
	format(betterDates,
		"%a %b %d")

  mean(betterDates)
  max(betterDates)
  min(betterDates)


# fixing centuries:
	dates <- c("05/27/84", "07/07/05", "08/17/20")
	betterDates <- as.Date(dates, "%m/%d/%y")

	correctCentury <- as.Date(ifelse(betterDates > Sys.Date(), 
		format(betterDates, "19%y-%m-%d"), 
		format(betterDates)))