[R] dataframe: visualization as tiles(?)

[Itay Furman]

Dear R users,

I remember seeing somewhere a method of visualizing a set of 
observations on two variables x and y in the following way

	   x=0       x=1

	|-------| |-------|
  y=-1	|	| |	  |
	|-------| |	  |
	 	  |	  |
	|-------| |	  |
	|	| |-------|
  y=0	|	|
	|	| |-------|
	|-------| |	  |
	 	  |-------|
	|-------|
  y=1	|       | |-------|
	|-------| |-------|

where x = 0 or 1; y = -1, 0, 1. The 'tile' area represents 
the count of observations with corresponding x and y values.

Now, I don't remember what is the name of the functions that 
support such plots.

I tried help.search("*tile*"); I skimmed the documentation of 
the 'lattice' package. Both seem not to be what I remembered.

Please send me pointers.

	Thanks in advance
	Itay