version 0.1-6

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: kulife
-Version: 0.1-5
+Version: 0.1-6
 Title: Data sets and functions from the Faculty of Life Sciences,
         University of Copenhagen
 Author: Claus Ekstrom <ekstrom@life.ku.dk>, Ib M. Skovgaard
@@ -9,6 +9,6 @@ Enhances: XML
 Description: Provides various functions and data sets from experiments
         at the Faculty of Life Sciences, University of Copenhagen
 License: GPL-2
-Packaged: 2011-04-11 19:17:53 UTC; claus
+Packaged: 2011-06-25 23:32:25 UTC; claus
 Repository: CRAN
-Date/Publication: 2011-04-12 06:22:23
+Date/Publication: 2011-06-26 05:25:08

R/auc.r

@@ -0,0 +1,13 @@
+auc <- function(x, y, from=min(x), to=max(x), ...) {
+
+  if (length(x) != length(y))
+    stop("x and y must have the same length")
+
+  if (length(unique(x))<2)
+    return(NA)
+
+  values <- approx(x, y, xout=sort(unique(c(from, to, x))),...)
+
+  res <- .5*sum(diff(values$x)*(values$y[-1]+values$y[-length(values$y)]))
+  res
+}

man/auc.Rd

@@ -0,0 +1,73 @@
+\name{auc}
+\alias{auc}
+\title{
+  Compute the area under the curve for two vectors.
+}
+\description{  
+    Compute the area under the curve using linear interpolation for two
+    vectors where one corresponds to the x values and the other
+    corresponds to the y values.    
+}
+\usage{
+auc(x, y, from = min(x), to = max(x), ...)
+}
+\arguments{
+  \item{x}{a numeric vector of x values.
+}
+  \item{y}{a numeric vector of y values of the same length as x.
+}
+  \item{from}{The value from where to start calculating the area under
+    the curve. Defaults to the smallest x value.
+}
+\item{to}{
+  The value from where to end the calculation of the area under
+    the curve. Defaults to the smallest y value.
+}
+  \item{\dots}{
+additional arguments passed on to approxfun. In particular rule can be
+set to determine how values outside the range of x is handled.
+}
+}
+\details{
+  auc is implemented using the approx function together with
+  the composite trapezoid rule.  approx creates a function that performs the linear
+  interpolation between points and the trapezoid rule calculates the numerical
+  integral, and by combining these we can handle unsorted time values,
+  missing observations, ties for the time values, and integrating over
+  part of the area or even outside the area. 
+}
+\value{The value of the area under the curve.
+}
+%\references{
+%% ~put references to the literature/web site here ~
+%}
+\author{
+Claus Ekstrom \email{ekstrom@life.ku.dk}
+}
+%\note{
+%%  ~~further notes~~
+%}
+
+%% ~Make other sections like Warning with \section{Warning }{....} ~
+
+\seealso{
+\code{\link{approxfun}} and \code{\link{integrate}}
+}
+\examples{
+x <- 1:4
+y <- c(0, 1, 1, 5)
+auc(x, y)
+
+# AUC from 0 to max(x) where we allow for extrapolation
+auc(x, y, from=0, rule=2)    
+
+# Use value 0 to the left
+auc(x, y, from=0, rule=2, yleft=0)
+
+# Use 1/2 to the left
+auc(x, y, from=0, rule=2, yleft=.5)
+}
+% Add one or more standard keywords, see file 'KEYWORDS' in the
+% R documentation directory.
+\keyword{ ~kwd1 }
+\keyword{ ~kwd2 }% __ONLY ONE__ keyword per line