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Date computations

date_compute.Rd

addToDate adds a period of time to a date string and returns a new date string. diffDate takes the difference between two dates and returns in the specified unit of time. compareDate compares the difference between two dates.

Usage

addToDate(
  org.date,
  delta,
  date.format = "MM.DD.YYYY",
  units = c("days", "weeks", "months", "years"),
  existing.missing.codes = NA,
  return.missing.code = NA,
  sep = "/"
)

diffDate(
  d1,
  d2,
  date.format = "MM.DD.YYYY",
  units = c("days", "weeks", "months", "years"),
  existing.missing.codes = NA,
  return.missing.code = NA,
  sep = "/"
)

compareDate(
  d1,
  d2,
  date.format = "MM.DD.YYYY",
  existing.missing.codes = NA,
  return.missing.code = NA,
  sep = "/"
)

Arguments

org.date

original date

delta

amount of time to add to org.date

date.format

how to format the resulting date

units

for addToDate, the unit of time for delta; for diffDate, the unit of time for which to take the difference. Defaults to "days".

existing.missing.codes

missing dates

return.missing.code

what to return if there is a missing input

sep

date separator string

d1

later date

d2

earlier date

Value

addDate returns the new date after adding delta to org.date.

diffDate returns the difference between two dates d1 - d2 in the specified unit of time.

compareDate returns 1 if d1 > d2, -1 if d1 < d2, and 0 if d1 == d2.

Details

If delta is negative, then the returned date will be earlier than org.date. The output date format will be the same as the input date format.

The unit of time to add to or return in can be in "days", "weeks", "months", or "years". compareDate calls diffDate and returns integer values specifying which date is earlier (or if they are the same). d1 should be later than d2 so the function returns nonnegative values.

Author

Samuel Leung, Derek Chiu

Examples

## Adding to a date
addToDate("2014/07/08", 10, date.format = "YYYY.MM.DD")
#> [1] "2014/07/18"
addToDate("2014-07-08", 10, date.format = "YYYY.MM.DD", sep = "-")
#> [1] "2014-07-18"
addToDate("2014/07/08", 10, date.format = "YYYY.MM.DD", units = "months")
#> [1] "2015/05/09"
addToDate("2014/07/08", -10, date.format = "YYYY.MM.DD", units = "years")
#> [1] "2004/07/07"

## Date differences
# Later date comes first, subtracts the second date
diffDate("2003/03/21", "1992/01/27", date.format = "YYYY.MM.DD")
#> [1] 4071

# Otherwise negative
diffDate("1992/01/27", "2003/03/21", date.format = "YYYY.MM.DD")
#> [1] -4071

# Different separator
diffDate("2003-03-21", "1992-01-27", date.format = "YYYY.MM.DD", sep = "-")
#> [1] 4071

## Date comparisons
compareDate("01/22/1949", "04/13/1950", date.format = "MM.DD.YYYY")
#> [1] -1
compareDate("04/13/1950", "04/13/1950", date.format = "MM.DD.YYYY")
#> [1] 0
compareDate("04/13/1959", "04/13/1950", date.format = "MM.DD.YYYY")
#> [1] 1
compareDate("01-22-1949", "04-13-1950", date.format = "MM.DD.YYYY", sep =
"-")
#> [1] -1