In R, how to set the breaks of x-axis?

Question

Say here is my code:

plot(data ylab="x", xlab="y", xlim=c(1, 13))

But the x-axis of the plot presented like this:

As you see, the x-axis presented from 2 to 12 by 2. However, I want it shown from 1 to 13 by 1 step, how can I realize that?

Answer 1

You've defined the limits for your axis; however, R is inserting the "default" values for it.

To alter them, you need to

1. "Override" the creation of the axis with xaxt='n'
2. Define a custom axis

So, let's get it done!

plot(data, ylab="x", xlab="y", xlim=c(1, 13), xaxt='n')
# Now, define a custom axis
axis(side = 1, at=1:13)

This will give you what you want.

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From the documentation, axis():

Description

Adds an axis to the current plot, allowing the specification of the side, position, labels, and other options.

Usage

axis(side, at = NULL, labels = TRUE, tick = TRUE, line = NA, pos = NA, outer = FALSE, font = NA, lty = "solid", lwd = 1, lwd.ticks = lwd, col = NULL, col.ticks = NULL, hadj = NA, padj = NA, ...)

Some of the most used arguments are:

• side (integer) 1=below, 2=left, 3=above and 4=right.
• at (vector) position of the tick marks
• labels (vector) labels for the tick marks. The vector must be the same size of at. If ommited, the values of at will be used. FALSE hides any labels

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Useful reference:

• The Quick-R tutorial | Axes and text