date_compute: Date computations

In TalhoukLab/biostatUtil: Utility Functions Used in Biostatistics Projects

Date computations

Description

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

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.

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.

Author(s)

Samuel Leung, Derek Chiu

Examples

## Adding to a date
addToDate("2014/07/08", 10, date.format = "YYYY.MM.DD")
addToDate("2014-07-08", 10, date.format = "YYYY.MM.DD", sep = "-")
addToDate("2014/07/08", 10, date.format = "YYYY.MM.DD", units = "months")
addToDate("2014/07/08", -10, date.format = "YYYY.MM.DD", units = "years")

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

# Otherwise negative
diffDate("1992/01/27", "2003/03/21", date.format = "YYYY.MM.DD")

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

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

TalhoukLab/biostatUtil documentation built on April 14, 2025, 4:15 a.m.