plotrix (version 2.4-6)

taylor.diagram: Taylor diagram

Description

Display a Taylor diagram.

Usage

taylor.diagram(ref,model,add=FALSE,col="red",pch=19,pos.cor=TRUE,
  xlab="",ylab="",main="Taylor Diagram",show.gamma=TRUE,ref.sd=FALSE,
  pcex=1,normalize=FALSE,...)

Arguments

ref

numeric vector - the reference values.

model

numeric vector - the predicted model values.

add

whether to draw the diagram or just add a point.

col

the color for the points displayed.

pch

the type of point to display.

pos.cor

whether to display only positive (TRUE) or all values of correlation (FALSE).

xlab,ylab

plot axis labels.

main

title for the plot.

show.gamma

whether to display standard deviation arcs around the reference point (only for pos.cor=TRUE).

ref.sd

whether to display the arc representing the reference standard deviation.

pcex

character expansion for the plotted points.

normalize

whether to normalize the models so that the reference has a standard deviation of 1.

...

Additional arguments passed to plot.

Value

• The values of par that preceded the function. This allows the user to add points to the diagram, then restore the original values. This is only necessary when using the 0 to 1 correlation range.

Details

The Taylor diagram is used to display the quality of model predictions against the reference values, typically direct observations. A diagram is built by plotting one model against the reference, then adding alternative model points. If normalize=TRUE when plotting the first model, remember to set it to TRUE when plotting additional models. Two displays are available. One displays the entire range of correlations from -1 to 1. Setting pos.cor to FALSE will produce this display. The -1 to 1 display includes a radial grid for the correlation values. When pos.cor is set to TRUE, only the range from 0 to 1 will be displayed. The gamma lines and the arc at the reference standard deviation are optional in this display.

References

Taylor, K.E. (2001) Summarizing multiple aspects of model performance in a single diagram. Journal of Geophysical Research, 106: 7183-7192.

Examples

# fake some reference data
 ref<-rnorm(30,sd=2)
 # add a little noise
 model1<-ref+rnorm(30)/2
 # add more noise
 model2<-ref+rnorm(30)
 # display the diagram with the better model
 oldpar<-taylor.diagram(ref,model1)
 # now add the worse model
 taylor.diagram(ref,model2,add=TRUE,col="blue")
 # get approximate legend position
 lpos<-1.5*sd(ref)
 # add a legend
 legend(lpos,lpos,legend=c("Better","Worse"),pch=19,col=c("red","blue"))
 # now restore par values
 par(oldpar)
 # show the "all correlation" display
 taylor.diagram(ref,model1,pos.cor=FALSE)
 taylor.diagram(ref,model2,add=TRUE,col="blue")