Question

I’ve a zoo object, with a yearqtr index, covering about 50 years. When plotted the x-axis shows labels every 10 years, which feels a bit barren:

b=zoo(1:200,as.yearqtr(1900+seq(1,200)/4))
plot(b)

Some study got me this:

plot(b,xaxt="n");axis(1,time(b))

Which feels like swinging from one extreme to the other, as the x-axis is a blur of ticks, with ugly fractional labels. Is there an easy way to have it just show years? (What I was looking for initially was a way to say: “lower the x-axis label spacing a bit”, but there seems nothing like that? cex.axis just alters the font-size.)

Answer 1

Did you read help(axis)?

Here is one way, just creating a simple index every four quarters:

R> ind <- seq(1, length(b), by=4)

and using it to index the axis placement and labels:

R> plot(b,xaxt="n")
R> axis(1,time(b)[ind], format(time(b)[ind]), las=2, cex.axis=0.5)

I used las=2 and the lower cex value to make this fit. Once every year may still be too plenty.

Computing “good” axis labels is really hard.