box plot

par(mai=c(2,1.5,1.5,.5))
par(mgp=c(5, 0.5, 0))

b = boxplot(log2(mat.sel$HL)~mat.sel$type, xlab = "pA_type", ylab = "HL (hr)", las = 3, cex.axis=0.7, varwidth=T)
boxplot(log2(mat.sel$HL)~mat.sel$type, xlab = "pA_type", ylab = "HL (hr)", las = 3, cex.axis=0.7, varwidth=T, names=paste(b$names, "(n=", b$n, ")"))