minor axis ticks in trellis graphics?

Dear Martin,

Mea culpa! I screwed up. I was answering (not well, at that) a
different question and somehow managed to make it a response to
your request.

Here's what may be a solution to your problem.
(see also this post by ilai:
<<https://stat.ethz.ch/pipermail/r-help/attachments/20120718/7133b673/attachment.pl>>)

We define appropriate locations for the x-ticks to go with
suitably defined labels and corresponding tick lengths.

## data:
    d <- data.frame(x = 1:11, y = rnorm(11))

## Where to put ticks and labels
    myat  <- 1:11
    mylab <- head(c(rbind(LETTERS[1:6], "")), -1)
       # putting letters at every second tick

## lengths of ticks
    mytck <- head(c(rbind(rep(1,6), .5)), -1)

## myat, mylab, mytck should all be same length

## plot
    xyplot(y ~ x, data = d, xlab="",
      scales = list(x = list(
                 at = myat, labels = mylab)),
      par.settings = list(
                 axis.components = list(
                    bottom = list(tck = mytck))))

## Try it with different myat etc to see how it works

    myat  <- seq(1, 11, by = 2/3)
    mylab <- head(c(rbind(LETTERS[1:6], "", "")), -2)
    mytck <- head(c(rbind(rep(2,6), .5, .5)), -2)

    myat  <- seq(1, 11, by = 1/2)
    mylab <- head(c(rbind(LETTERS[1:6], "", "", "")), -3)
    mytck <- head(c(rbind(rep(2,6), .5, 1, .5)), -3)

The trick is in constructing suitable vectors myat, mylab,
and mytck which you can do any way you like but I would
check that the lengths are equal (recycling works fine
for simple cases but always seems to trip me up in more
complicated cases).

Peter Ehlers

Dear Peter,

Thank You very much for your suggestion. However, it seems to me to make a completely new notation to the x axis. While I just need to add minor ticks to the axis, that is smaller ticks inbetween the basic ticks.
The other option would be to say which ticks to be small and which big, but I have no idea how.

Any suggestions will be appreciated.

Best regards,

Martin

<< embarassing junk from P. Ehlers cut >>