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dttr2

dttr2 (Dates, Times and dateTimes in R) is a light-weight R package to perform simple manipulations on date (Date), datetime (POSIXct) and time (hms) vectors (collectively referred to as date/times).

Key design principles include

  1. use existing classes (Date, POSIXct, hms)
  2. date/times are discrete (floor when encountered)
  3. times are times (wrap when encountered)
  4. maintain the current timezone (principle of least astonishment)
  5. the origin is always assumed to be 1970-01-01 UTC (keep it simple)

Installation

To install the latest development version from GitHub

if(!"remotes" %in% installed.packages()[,1]) 
  install.packages("remotes")
remotes::install_github("poissonconsulting/dttr2")

To install the latest development version from the Poisson drat repository

if(!"drat" %in% installed.packages()[,1]) 
  install.packages("drat")
drat::addRepo("poissonconsulting")
install.packages("dttr2")

Introduction

Time Units

dttr2 floors any date/time objects it encounters to the nearest time unit (by default days for Date and seconds for POSIXct and hms).

library(dttr2)
date <- as.Date(1.75, origin = "1970-01-01")
date
#> [1] "1970-01-02"
as.numeric(date)
#> [1] 1.75

date <- dtt_date(date)
date
#> [1] "1970-01-02"
as.numeric(date)
#> [1] 1

Similarly, the time unit accessor (dtt_second(), dtt_minute() etc) and settor functions as well as the functions to add (ie dtt_add_seconds()) and subtract time units return or require integers.

dtt_day(date)
#> [1] 2
dtt_add_days(date, 2L)
#> [1] "1970-01-04"
dtt_add_months(date, 24L)
#> [1] "1972-01-02"

Times

dttr2 wraps negative times or times greater than 23:59:59 to the actual clock time.

time <- hms::as.hms(-3)
time
#> -00:00:03
dtt_time(time)
#> 23:59:57
dtt_time(hms::as.hms("24:00:00"))
#> 00:00:00

Time Zones

The user can override the default time zone (UTC) when handling POSIXct vectors using dtt_set_default_tz().

dtt_default_tz()
#> [1] "UTC"
date_time <- dtt_date_time("1970-01-01 03:00:00")
dtt_set_default_tz("Etc/GMT+10")
dtt_default_tz()
#> [1] "Etc/GMT+10"
date_time
#> [1] "1970-01-01 03:00:00 UTC"

They can assign a new time zone to a POSIXct object whilst leaving the clock time unchanged using dtt_set_tz() or adjust the time zone so that clock (but not the actual) time is altered using dtt_adjust_tz()

date_time
#> [1] "1970-01-01 03:00:00 UTC"
dtt_set_tz(date_time)
#> [1] "1970-01-01 03:00:00 -10"
dtt_adjust_tz(date_time)
#> [1] "1969-12-31 17:00:00 -10"

Combining Dates and Times

dttr2 makes it easy to decompose POSIXct vectors into Date and hms vectors and then recombine them again.

As neither dates nor times have associated time zones unless the user passes a value they are assigned the default time zone.

date_time
#> [1] "1970-01-01 03:00:00 UTC"
date <- dtt_date(date_time)
date
#> [1] "1970-01-01"
time <- dtt_time(date_time)
time
#> 03:00:00
dtt_date_time(date, time)
#> [1] "1970-01-01 03:00:00 -10"

Inspiration

dttr2 was influenced by lubridate. It aims to provide a more light-weight alternative for simple manipulations.

Contribution

Please report any issues.

Pull requests are always welcome.

Please note that this project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.