R Draw All Axis Labels (Prevent Some From Being Skipped)

Question

When I manually add the following labels with (axis(1, at=1:27, labels=labs[0:27])):

> labs[0:27]
 [1] \"0\\n9.3%\"  \"1\\n7.6%\"  \"2\\n5.6%         


        

Answer 1

I had a similar problem where I wanted to stagger the labels and get them to print without losing some. I created two sets of ticks showing second set below the other to make it look as if it staggers.

xaxis_stagger = function(positions,labels) {
  odd=labels[seq(1,length(labels),2)]
  odd_pos=positions[seq(1,length(positions),2)]
  even=labels[seq(2,length(labels),2)]  
  even_pos=positions[seq(2,length(positions),2)]
  axis(side=1,at=odd_pos,labels=odd)
  axis(side=1,at=even_pos,labels=even,padj=1.5)
}

So you give the positions where you want the ticks to be and the labels for those ticks and this would then re-organise it into two sets of axis and plot them on the original plot. Original plot would be done with xaxt="n".

Answer 2

Although there are some good answers here, the OP didn't want to resize the labels or change anything about the plot besides fitting all of the axis labels. It's annoying, since often there appears to be plenty of room to fit all of the axis labels.

Here's another solution. Draw the plot without the axis, then add ticks with empty labels. Store the positions of the ticks in an object, so then you can go through each one and place it in the correct position on the axis.

plot(1:10, 1:10, yaxt = "n") axis_ticks = axis(2, axTicks(2), labels = rep("", length(axTicks(2)))) for(i in axis_ticks) axis(2, i)

Answer 3

?axis tells you that:

The code tries hard not to draw overlapping tick labels, and so will omit labels where they would abut or overlap previously drawn labels. This can result in, for example, every other tick being labelled. (The ticks are drawn left to right or bottom to top, and space at least the size of an ‘m’ is left between labels.)

Play with cex.axis so that labels are small enough to fit without overlapping

labs <-c("0\n9.3%","1\n7.6%","2\n5.6%","3\n5.1%","4\n5.7%","5\n6.5%","6\n7.3%",
         "7\n7.6%","8\n7.5%","9\n7%", "10\n6.2%","11\n5.2%","12\n4.2%",12:27)
plot(1:27,xaxt = "n")
axis(side=1, at=1:27, labels=labs[0:27],cex.axis=0.35)

If you widen you graph (manually by dragging or programmatically), you can increase the size of your labels.

Answer 4

If you really want to force all labels to display, even when they are very close or overlapping, you can "trick" R into displaying them by adding odd and even axis labels with separate commands, as follows:

labs <-c("0\n9.3%","1\n7.6%","2\n5.6%","3\n5.1%","4\n5.7%","5\n6.5%","6\n7.3%",
         "7\n7.6%","8\n7.5%","9\n7%", "10\n6.2%","11\n5.2%","12\n4.2%",13:27)
n=length(labs)
plot(1:28, xaxt = "n")
axis(side=1, at=seq(1,n,2), labels=labs[seq(1,n,2)], cex.axis=0.6)
axis(side=1, at=seq(2,n,2), labels=labs[seq(2,n,2)], cex.axis=0.6)

You can play with cex.axis to get the text size that you want. Note, also, that you may have to adjust the number of values in at= and/or labels= so that they are equal.

I agree with @PLapointe and @joran that it's generally better not to tamper with R's default behavior regarding overlap. However, I've had a few cases where axis labels looked fine even when they weren't quite a full "m-width" apart, and I hit on the trick of alternating odd and even labels as a way to get the behavior I wanted.

Answer 5

Perhaps draw and label one tick at a time, by calling axis repeatedly using mapply...

For example, consider the following data:

x = runif(100)*20
y = 10^(runif(100)*3)

The formula for y might look a bit odd; it gives random numbers distributed across three orders of magnitude such that the data will be evenly distributed on a plot where the y axis is on a log scale. This will help demonstrate the utility of axTicks() by calculating nice tick locations for us on a logged axis.

By default:

plot(x, y, log = "y")

returns:

Notice that 100 and 1000 labels are missing.

We can instead use:

plot(x, y, log = "y", yaxt = "n")
mapply(axis, side = 2, at = axTicks(2), labels = axTicks(2))

which calls axis() once for each tick location returned by axTicks(), thus plotting one tick at a time. The result:

What I like about this solution is that is uses only one line of code for drawing the axis, it prints exactly the default axis R would have made, except all ticks are labeled, and the labels don't go anywhere when the plot is resized:

I can't say the axis is useful in the resized example, but it makes the point about axis labels being permanent!

For the first (default) plot, note that R will recalculate tick locations when resizing.

For the second (always labeled) plot, the number and location of tick marks are not recalculated when the image is resized. The axis ticks calculated by axTicks depend upon the size of the display window when the plot is first drawn.

If you want want to force specific tick locations, try something like:

plot(x, y, log = "y", yaxt = "n")
mapply(axis, side = 2, at = c(1,10,100, 1000), labels = c("one", "ten", "hundred", "thousand"))

which yields:

Answer 6

@PLapointe just posted what I was going to say, but omitted the bonus answer.

Set padj = 0.5 in axis to move the labels down slightly.