Frequency histogram with negative value.

frequency histogram.r

d.class <- seq(25, 200, by=25) # DBH class
class <- c()
for(i in 1 : (length(d.class) - 1)){
	class <- append(class, paste(d.class[i], "-" ,d.class[i + 1], "cm"))
}

imm.class1 <- c(30, 20, 10, 5, 0, 0, 0)
imm.class2 <- c(0, 0, 5, 10, 5, 0, 0)
imm.class3 <- c(0, 0, 0, 0, 5, 2, 0)
immature <- matrix(
	rbind(imm.class1, imm.class2, imm.class3),
	nrow=3
)
#rownames(immature) <- c("class1", "class2", "class3")
#colnames(immature) <- c(class)

mat.class1 <- c(0, 0, 0, 0, 0, 0, 0)
mat.class2 <- c(0, 0, 5, 10, 8, 5, 0)
mat.class3 <- c(0, 0, 2, 10, 15, 20, 20)
mature <- matrix(
	rbind(mat.class1, mat.class2, mat.class3),
	nrow=3
)
#rownames(mature) <- c("class1", "class2", "class3")
#colnames(mature) <- c(class)

yrange <- c(-40, 40)
COL <- c("tomato", "turquoise", "purple")

par(mar=c(7, 4, 4, 2))
barplot(
	immature,
	ylim=yrange,
	las=2,
	space=0,
	names.arg=class,
	col=COL,
	ylab="# ind.")
par(new=T)
barplot(
	-mature,
	ylim=yrange,
	space=0,
	axes=F,
	las=2,
	col=COL)