gaschrom {ptw} | R Documentation |
The object gaschrom
contains 16 calibration GC traces, measured
at 5,000 time points. A peak-picked version is available as object
gaschrom.st
(see example).
data(gaschrom)
Claire Boucon, Unilever
Eilers, P.H.C. (2004) "Parametric Time Warping", Analytical Chemistry, 76 (2), 404 – 411.
data(gaschrom) ## the gaschrom.st object has been generated in the following way: ## Not run: pick.peaks <- function(x, span) { span.width <- span * 2 + 1 loc.max <- span.width + 1 - apply(embed(x, span.width), 1, which.max) loc.max[loc.max == 1 | loc.max == span.width] <- NA pks <- loc.max + 0:(length(loc.max)-1) pks <- pks[!is.na(pks)] pks.tab <- table(pks) pks.id <- as.numeric(names(pks.tab)[pks.tab > span]) cbind(rt = pks.id, I = x[pks.id]) } gaschrom <- t(apply(gaschrom, 1, baseline.corr)) gaschrom.st <- lapply(1:nrow(gaschrom), function(ii) pick.peaks(gaschrom[ii,], span = 11)) ## remove peaks with an intensity below 10 gaschrom.st <- lapply(gaschrom.st, function(pk) pk[pk[,2] >= 10,]) ## End(Not run) plot(gaschrom[1,], type = "l", xlim = c(3000, 3500), ylim = c(0, 200)) abline(h = 10, lty = 2, col = 2) abline(v = gaschrom.st[[1]], col = 4)