Lengthen tick marks in ggplot2

Question

Simple question I am trying to lengthen the tick marks in ggplot2 on the axis - how?

plot <- plot + theme(axis.ticks = element_line(colour = "black", size =2))

If increase the size it only seems to increase the width of them, not the length?

Answer 1

You need axis.ticks.length, i.e.

plot + theme(axis.ticks.length = unit(1, "cm"))