Compute Duration

Source: R/compute_duration.R

Compute duration between two dates, e.g., duration of an adverse event, relative day, age, ...

compute_duration(
  start_date,
  end_date,
  in_unit = "days",
  out_unit = "days",
  floor_in = TRUE,
  add_one = TRUE,
  trunc_out = FALSE,
  type = "duration"
)

Arguments

start_date

The start date

A date or date-time object is expected.

Refer to derive_vars_dt() to impute and derive a date from a date character vector to a date object.

Refer to convert_dtc_to_dt() to obtain a vector of imputed dates.

Default value

none

end_date

The end date

A date or date-time object is expected.

Refer to derive_vars_dt() to impute and derive a date from a date character vector to a date object.

Refer to convert_dtc_to_dt() to obtain a vector of imputed dates.

Default value

none

in_unit

Input unit

See floor_in and add_one parameter for details.

Permitted Values (case-insensitive):

For years: "year", "years", "yr", "yrs", "y"

For months: "month", "months", "mo", "mos"

For days: "day", "days", "d"

For hours: "hour", "hours", "hr", "hrs", "h"

For minutes: "minute", "minutes", "min", "mins"

For seconds: "second", "seconds", "sec", "secs", "s"

Default value

"days"

out_unit

Output unit

The duration is derived in the specified unit

Permitted Values (case-insensitive):

For years: "year", "years", "yr", "yrs", "y"

For months: "month", "months", "mo", "mos"

For weeks: "week", "weeks", "wk", "wks", "w"

For days: "day", "days", "d"

For hours: "hour", "hours", "hr", "hrs", "h"

For minutes: "minute", "minutes", "min", "mins"

For seconds: "second", "seconds", "sec", "secs", "s"

Default value

"days"

floor_in

Round down input dates?

The input dates are round down with respect to the input unit, e.g., if the input unit is 'days', the time of the input dates is ignored.

Permitted values

TRUE, FALSE

Default value

TRUE

add_one

Add one input unit?

If the duration is non-negative, one input unit is added. i.e., the duration can not be zero.

Permitted values

TRUE, FALSE

Default value

TRUE

trunc_out

Return integer part

The fractional part of the duration (in output unit) is removed, i.e., the integer part is returned.

Permitted values

TRUE, FALSE

Default value

FALSE

type

lubridate duration type.

See below for details.

Permitted values

"duration", "interval"

Default value

"duration"

Value

The duration between the two date in the specified unit

Details

The output is a numeric vector providing the duration as time from start to end date in the specified unit. If the end date is before the start date, the duration is negative.

Duration Type

The lubridate package calculates two types of spans between two dates: duration and interval. While these calculations are largely the same, when the unit of the time period is month or year the result can be slightly different.

The difference arises from the ambiguity in the length of "1 month" or "1 year". Months may have 31, 30, 28, or 29 days, and years are 365 days and 366 during leap years. Durations and intervals help solve the ambiguity in these measures.

The interval between 2000-02-01 and 2000-03-01 is 1 (i.e. one month). The duration between these two dates is 0.95, which accounts for the fact that the year 2000 is a leap year, February has 29 days, and the average month length is 30.4375, i.e. 29 / 30.4375 = 0.95.

For additional details, review the lubridate time span reference page.

See also

derive_vars_duration()

Date/Time Computation Functions that returns a vector: compute_age_years(), compute_dtf(), compute_tmf(), convert_date_to_dtm(), convert_dtc_to_dt(), convert_dtc_to_dtm(), impute_dtc_dt(), impute_dtc_dtm()

Examples

library(lubridate)
#> 
#> Attaching package: ‘lubridate’
#> The following objects are masked from ‘package:base’:
#> 
#>     date, intersect, setdiff, union

# Derive duration in days (integer), i.e., relative day
compute_duration(
  start_date = ymd_hms("2020-12-06T15:00:00"),
  end_date = ymd_hms("2020-12-24T08:15:00")
)
#> [1] 19

# Derive duration in days (float)
compute_duration(
  start_date = ymd_hms("2020-12-06T15:00:00"),
  end_date = ymd_hms("2020-12-24T08:15:00"),
  floor_in = FALSE,
  add_one = FALSE
)
#> [1] 17.71875

# Derive age in years
compute_duration(
  start_date = ymd("1984-09-06"),
  end_date = ymd("2020-02-24"),
  trunc_out = TRUE,
  out_unit = "years",
  add_one = FALSE
)
#> [1] 35

# Derive duration in hours
compute_duration(
  start_date = ymd_hms("2020-12-06T9:00:00"),
  end_date = ymd_hms("2020-12-06T13:30:00"),
  out_unit = "hours",
  floor_in = FALSE,
  add_one = FALSE,
)
#> [1] 4.5