[R] pairs(), expression in label and color in text.panel

[Johannes Radinger]

Hello,

I'd like to add custom labels to my pair() plot. These
labels include math expression but they aren't correctly
displayed...

Further, I want that the boxes for the text.panel (diagonal)
have an other background color (grey80). Is that generally 
possible? If yes how do I have to set it?

What I've so far is:


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 <- 0.5/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, paste(txt,Signif), cex = 2)
}

#correlation pair plot
pairs(df, labels=c(expression(alpha),"text",expression(beta)), lower.panel=panel.smooth, upper.panel=panel.cor)


Maybe someone knows how to do that and can give some hints...

/Johannes

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