[R] decrease amount of ticks on y axis in lattice levelplot

[Bram Kuijper]

Hi all,

How can I decrease the number of ticks on the y-axis in a lattice 
levelplot()? I have as many ticks displayed on the y-axis as I have 
columns of data (1000 columns), how can I decrease this amount of ticks, 
while still properly displaying all the data?

Note that I get my data from a matrix object, in which the z-values of 
the levelplot are the actual values in the matrix, whereas the row and 
column names are the x and y ticks (and thus character data). I guess 
that is character data is the root of the problem, but I don't know how 
to solve it.

I tried to change the amount of ticks using yscale.components, but this 
doesn't work:

yscale.components.myY <- function(...) {
	Y <- yscale.components.default(...)
	Y$left$ticks$at <- pretty(1,n=10)
	Y$left$labels$at <- pretty(1,n=10)

	return(Y)
}
print(levelplot(my_matrix),cuts=100,yscale.components=yscale.components.myY)

My full code can be found on pastebin:
http://pastebin.com/m16b267f9

thanks in advance for any help on this,

Bram Kuijper