time_calc: Create time variables for usage in NONMEM analyses

In amp.dm: Data Management Tools for Pharmacometrics

Create time variables for usage in NONMEM analyses

Description

This function calculates the most important time variables based on multiple variables in a data frame.

Usage

time_calc(
  data,
  datetime,
  evid = NULL,
  addl = NULL,
  ii = NULL,
  amt = "AMT",
  id = "ID",
  dig = 2
)

Arguments

data	data frame to perform the calculations on
datetime	character identifying the date/time variable (POSIXct) within the data frame
evid	character identifying the event ID (EVID) within the data frame
addl	character identifying the additional dose levels (ADDL) within the data frame
ii	character identifying the interdose interval (II) within the data frame
amt	character identifying the amount variable (only needed if evid is not provided)
id	character identifying the ID or subject variable
dig	numeric indicating with how many digits the resulting times should be available

Details

The function calculates the TIME, TALD (time after last dose) and TAFD (time after first dose). The different time variables are calculated in hours, where a POSIXct for the datetime variable is expected. The function takes into account ADDL and II records when provided, to correctly identify the TALD. One must be cautious however when having ADDL/II and a complex dosing schedule (e.g. alternating dose schedules, more than 1 dose per day, multiple compounds administration). In general it is good practice to double check the output for multiple subjects in case of complex designs including ADDL/II.

Value

a data frame with the calculated times

Author(s)

Richard Hooijmaijers

Examples

dfrm <- data.frame(ID=rep(1,5), dt=Sys.time() + c(0,8e+5,1e+6,2e+6,3e+6),
                   AMT=c(NA,10,NA,0,NA), II=rep(24,5),EVID=c(0,1,0,1,0))
time_calc(dfrm,"dt","EVID")

amp.dm documentation built on March 13, 2026, 5:08 p.m.