Five ways to visualize your pairwise comparisons
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In data analysis it is often nice to look at all pairwise combinations of continuous variables in scatterplots. Up until recently, I have used the function splom in the package lattice, but ggplot2 has superior aesthetics, I think anyway.
Here a few ways to accomplish the task:
# load packages
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require(lattice) require(ggplot2)1) Using base graphics, function “pairs”
pairs(iris[1:4], pch = 21)
splom(~iris[1:4])
plotmatrix(iris[1:4])
ggcorplot( data = iris[1:4], var_text_size = 5, cor_text_limits = c(5,10))
panel.cor <- function(x, y, digits=2, prefix="", cex.cor)
{
usr <- par("usr"); on.exit(par(usr))
par(usr = c(0, 1, 0, 1))
r <- abs(cor(x, y))
txt <- format(c(r, 0.123456789), digits=digits)[1]
txt <- paste(prefix, txt, sep="")
if(missing(cex.cor)) cex <- 0.8/strwidth(txt)
test <- cor.test(x,y)
# borrowed from printCoefmat
Signif <- symnum(test$p.value, corr = FALSE, na = FALSE,
cutpoints = c(0, 0.001, 0.01, 0.05, 0.1, 1),
symbols = c("***", "**", "*", ".", " "))
text(0.5, 0.5, txt, cex = cex * r)
text(.8, .8, Signif, cex=cex, col=2)
}
pairs(iris[1:4], lower.panel=panel.smooth, upper.panel=panel.cor)
> system.time(pairs(iris[1:4])) user system elapsed 0.138 0.008 0.156 > system.time(splom(~iris[1:4])) user system elapsed 0.003 0.000 0.003 > system.time(plotmatrix(iris[1:4])) user system elapsed 0.052 0.000 0.052 > system.time(ggcorplot( + data = iris[1:4], var_text_size = 5, cor_text_limits = c(5,10))) user system elapsed 0.130 0.001 0.131 > system.time(pairs(iris[1:4], lower.panel=panel.smooth, upper.panel=panel.cor)) user system elapsed 0.170 0.011 0.200
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