#	matplotを簡単に使えるようにした関数
matplot2 <- function(df, lg.x=0.65, lg.y=1.0, col=1:6){
	tb.y <- tapply(df[,2], list(as.numeric(rownames(df)), df[,3]), mean)
	tb.x <- matrix(rep(df[,1], ncol(tb.y)), ncol=ncol(tb.y))
	matplot(tb.x, tb.y, col=col, xlab=colnames(df)[1], ylab=colnames(df)[2])
	legend(max(df[,1])*lg.x, max(df[,2])*lg.y,
	paste(1:ncol(tb.y), colnames(tb.y), sep="："), text.col=col)
}

#	matplotもどき
matplot3 <- function(df, ...){
	col <- as.numeric(df[[3]])
	pch <- as.character(col)
	plot(df[[1]], df[[2]], pch=pch, col=col)
}

# 使用方法
data(iris)
data <- data.frame(iris[,1], iris[,3], iris[,5])
matplot2(data)
matplot3(data)