Width of edge of the bars in R plots

Question

Is there a way to set the width the the edge of the bars in R plots? For example when I set

test <- read.csv(file="test4.csv",sep=",",head=TRUE)
pdf(file="test.pdf", height=4, width=6)
barplot(as.matrix(test[,2:ncol(test)]), col=heat.colors(10), space=0.5)
dev.off()

I get this.

But the edges of all the bars are very thick compared to the width of the bars themselves, hence the high level of black at the bottom and in the smaller bars.

Answer 1

You can set the line width before plotting.

opar <- par(lwd = 0.3)

This will make thinner bars but not affect your axes (as they are set separately).