Bioequivalence and Bioavailability Forum • TTT flawed in case of a lagtime…

TTT flawed in case of a lagtime… [🇷 for BE/BA]

posted by ElMaestro – Denmark, 2013-07-24 00:35 (4348 d 16:52 ago) – Posting: # 11043
Views: 9,080

Hi Helmut,

❝ Does anybody have a clever idea how I can find the lagtime in R without a loop? Essentially I would search backwards from t_max until I find the first NA.

Not thoroughly tested, but if I get your drift, then here's something to consider:
_{time=c(1,2,3,4,5,6,7,8,9,10)

conc=c(NA,NA,NA,5,19,56, 53,46,40, NA)

data=data.frame(time, conc)

d1=subset(data, !(is.na(conc))) ##d1 now holds everything not NA

Tmax=subset(d1, conc==max(d1[,2]))[1,1] ##records Tmax

d4=subset(data, (is.na(conc)) &(time<Tmax) ) ##takes all NA's observed until Tmax

Tlag=(subset(data, (is.na(conc))&&(time<Tmax)))[nrow(d4),1] ##Time of last observed NA before Tmax}

Not thoroughly tested though :PCchaos:

—
Pass or fail!
ElMaestro

Complete thread:

‘Automatic’ selection of time points for λz Helmut 2013-07-22 19:14
- New code Helmut 2013-07-23 02:06
  - TTT flawed in case of a lagtime… Helmut 2013-07-23 19:59
    - TTT flawed in case of a lagtime… martin 2013-07-23 20:22
    - TTT flawed in case of a lagtime…ElMaestro 2013-07-23 22:35
      - minimalistic R Helmut 2013-07-24 01:04
        
        Wow, very efficicient ElMaestro 2013-07-24 10:49
        
        R’s semantic riddles Helmut 2013-07-24 14:10