Bioequivalence and Bioavailability Forum

Hi ElMaestro,

❝ age taking its toll on your eyes? Go visit the veterinarian.

Sure. I’m a regular guest at my pet doctor. Where do you think I’m getting my pills from?

❝ -I had to read the online documentation to understand what which.max actually does.

Yeah, some of R’s functions are very efficient but difficult to comprehend. Martin once provided me with a framework full of lapply(), sweep(), aggregate(), simplify2array(), with(), etc. as a wrapper to functions used in sim’s. Speeded up the code at least 10fold. But: I read Cuneiform script more fluent than this gibberish.

In my code I use obscure one-liners only in sim’s where speed prevails over clarity.

❝ I wonder, how would Tmax be defined in cases of e.g.

❝ time <- c( 0,  1,  1.5,  2,  4,  5,  6,  7,  8,  9)

❝ conc <- c(NA, NA, 0.01, NA, 19, 56, 53, 46, 40, NA)

My code gives:
Tmax = 5
Tlag = 1
I’m happy with that. Or would you prefer to flag the 0.01 as crap and come up with a lagtime of 2? BTW, your code comes up with 1.5.

❝ - something like that is not entirely uncommon with OIPs, …

Not only with OIPs. We have discussed this issue occasionally (here and there).

❝ … some CROs are really spanking the 5500

Interesting hobby.

❝ … and manipulating the low QC integrations

They should not practice BDSM with their machines, but receive bastinado themselves. As a cap’tain you are familiar with the cat o’ nine tails.

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Edit: If time[1] is not given and no NAs occur before t_max, my code returns numeric(0), which cannot be used in further calculations.

1. No lag-time, zero as NA:
   time <- c( 0, 1, 1.5, 2,  4,  5,  6,  7,  8,  9)
conc <- c(NA, 1,   3, 5, 19, 56, 53, 46, 40, NA)
data <- data.frame(time, conc)
Tmax <- data$time[which(data$conc == max(data$conc[complete.cases(data)]))]
Tlag <- data$time[which.max(complete.cases(data))-1] cat("Tmax =", Tmax, "\nTlag =", Tlag, "\n")
Tmax = 5
Tlag = 0
   
2. No lag-time, zero time point not given:
   time <- c(1, 1.5, 2,  4,  5,  6,  7,  8,  9)
conc <- c(1,   3, 5, 19, 56, 53, 46, 40, NA)
data <- data.frame(time, conc)
Tmax <- data$time[which(data$conc == max(data$conc[complete.cases(data)]))]
Tlag <- data$time[which.max(complete.cases(data))-1] cat("Tmax =", Tmax, "\nTlag =", Tlag, "\n")
Tmax = 5
Tlag =
   Oops!
   
3. As above + workaround:
   if(length(Tlag) == 0) Tlag <- 0
cat("Tmax =", Tmax, "\nTlag =", Tlag, "\n")
Tmax = 5
Tlag = 0