Don't do calplot and lod for linear models from weighted

regression any more, since this is not supported (PR#8877).



git-svn-id: http://kriemhild.uft.uni-bremen.de/svn/chemCal@13 5fad18fb-23f0-0310-ab10-e59a3bee62b4

1 files changed, 16 insertions, 3 deletions

diff --git a/R/lod.R b/R/lod.R
index 39ce7b3..54618c8 100644
--- a/R/lod.R
+++ b/R/lod.R
@@ -10,7 +10,18 @@ lod.default <- function(object, ..., alpha = 0.05, beta = 0.05)
 
 lod.lm <- function(object, ..., alpha = 0.05, beta = 0.05)
 {
+  if (length(object$weights) > 0) {
+    stop(paste(
+      "\nThe detemination of a lod from calibration models obtained by",
+      "weighted linear regression requires confidence intervals for",
+      "predicted y values taking into account weights for the x values",
+      "from which the predictions are to be generated.",
+      "This is not supported by the internally used predict.lm method.",
+      sep = "\n"
+    ))
+  }
   xname <- names(object$model)[[2]]
+  yname <- names(object$model)[[1]]
   newdata <- data.frame(0)
   names(newdata) <- xname
   y0 <- predict(object, newdata, interval="prediction", 
@@ -28,7 +39,9 @@ lod.lm <- function(object, ..., alpha = 0.05, beta = 0.05)
   }
   lod.x <- optimize(f,interval=c(0,max(object$model[[xname]])))$minimum
   newdata <- data.frame(x = lod.x)
-  names(lod.x) <- xname
-  lod.y <-  predict(object, newdata = lod.x)
-  return(list(x = lod.x, y = lod.y))
+  names(newdata) <- xname
+  lod.y <-  predict(object, newdata)
+  lod <- list(lod.x, lod.y)
+  names(lod) <- c(xname, yname)
+  return(lod)
 }