psych (version 2.6.1)

scatterHist: Draw a scatter plot with associated X and Y histograms, densities and correlation

Description

Draw a X Y scatter plot with associated X and Y histograms with estimated densities. Will also draw density plots by groups, as well as distribution ellipses by group. Partly a demonstration of the use of layout. Also includes lowess smooth or linear model slope, as well as correlation and Mahalanobis distances

Usage

scatterHist(x,y=NULL,smooth=TRUE,ab=FALSE, correl=TRUE,data=NULL, density=TRUE,means=TRUE, 
   ellipse=TRUE,digits=2,method="pearson",cex.cor=1,cex.point=1,
   title="Scatter plot + density",
   xlab=NULL,ylab=NULL,smoother=FALSE,nrpoints=0,xlab.hist=NULL,ylab.hist=NULL,grid=FALSE,
   xlim=NULL,ylim=NULL,x.breaks=11,y.breaks=11,
   x.space=0,y.space=0,freq=TRUE,x.axes=TRUE,y.axes=TRUE,size=c(1,2),
   col=c("blue","red","black"),legend=NULL,transparency=.5,pch=21, show.d=TRUE,
   x.arrow=NULL,y.arrow=NULL,d.arrow=FALSE,cex.arrow=1,
      line.col="blue",alpha = .05,ci=TRUE, ci.col="light blue",...)
 
scatter.hist(x,y=NULL,smooth=TRUE,ab=FALSE, correl=TRUE,data=NULL,density=TRUE,
  means=TRUE, ellipse=TRUE,digits=2,method="pearson",cex.cor=1,cex.point=1,
  title="Scatter plot + density",
  xlab=NULL,ylab=NULL,smoother=FALSE,nrpoints=0,xlab.hist=NULL,ylab.hist=NULL,grid=FALSE,
  xlim=NULL,ylim=NULL,x.breaks=11,y.breaks=11,
  x.space=0,y.space=0,freq=TRUE,x.axes=TRUE,y.axes=TRUE,size=c(1,2),
  col=c("blue","red","black"),legend=NULL,transparency=.5,pch=21, show.d=TRUE,
   x.arrow=NULL,y.arrow=NULL,d.arrow=FALSE,cex.arrow=1,
      line.col="blue",alpha = .05,ci=TRUE, ci.col="light blue",...)

Details

Just a straightforward application of layout and barplot, with some tricks taken from pairs.panels. The various options allow for correlation ellipses (1 and 2 sigma from the mean), lowess smooths, linear fits, density curves on the histograms, and the value of the correlation. ellipse = TRUE implies smooth = TRUE. The grid option provides a background grid to the scatterplot.

If using grouping variables, will draw ellipses (defaults to 1 sd) around each centroid. This is useful when demonstrating Mahalanobis distances.

Formula input allows specification of grouping variables as well. )

For plotting data for two groups, Mahalobnis differences between the groups may be shown by drawing an arrow between the two centroids. This is a bit messy and it is useful to use pch="." in this case.

See Also

pairs.panels for multiple plots, multi.hist for multiple histograms and histBy for single variables with multiple groups. Perhaps the best example is found in the psychTools::GERAS data set.

Examples

data(sat.act)
with(sat.act,scatterHist(SATV,SATQ))
scatterHist(SATV ~ SATQ,data=sat.act)  #formula input

#or for something a bit more splashy
scatterHist(sat.act[5:6],pch=(19+sat.act$gender),col=c("blue","red")[sat.act$gender],grid=TRUE)
#better yet
scatterHist(SATV ~ SATQ + gender,data=sat.act) #formula input with a grouping variable

#If using a factor for grouping, we must first convert it to numeric
iris.1 <- char2numeric(iris,flag=FALSE)
scatterHist(Sepal.Width ~ Petal.Length + Species,data=iris.1, show.d=FALSE,
   main="Fisher's Iris example") #see pairs.panels