How to specify the actual x axis values to plot as x axis ticks in R

Question

I am creating a plot in R and I dont like the x axis values being plotted by R.

For example:

x <- seq(10,200,10)
y <- runif(x)

plot(x,y)

This plots a graph with the following values on the X axis:

50, 100, 150, 200

However, I want to plot the 20 values 10,20, 30 ... 200 stored in variable x, as the X axis values. I have scoured through countless blogs and the terse manual - after hours of searching, the closest I've come to finding anything useful is the following (summarized) instructions:

1. call plot() or par(), specifying argument xaxt='n'
2. call axis() e.g. axis(side = 1, at = seq(0, 10, by = 0.1), labels = FALSE, tcl = -0.2)

I tried it and the resulting plot had no x axis values at all. Is it possible that someone out there knows how to do this? I can't believe that no one has ever tried to do this before.

Answer 1

You'll find the answer to your question in the help page for ?axis.

Here is one of the help page examples, modified with your data:

Option 1: use xaxp to define the axis labels

plot(x,y, xaxt="n")
axis(1, xaxp=c(10, 200, 19), las=2)

Option 2: Use at and seq() to define the labels:

plot(x,y, xaxt="n")
axis(1, at = seq(10, 200, by = 10), las=2)

Both these options yield the same graphic:

---

PS. Since you have a large number of labels, you'll have to use additional arguments to get the text to fit in the plot. I use las to rotate the labels.