[R] lattice graph with free scales and reversed axis values

[David Winsemius]

> On Nov 5, 2016, at 3:59 PM, Naresh Gurbuxani <naresh_gurbuxani at hotmail.com> wrote:
> 
> I want to draw a lattice graph where different panels have different ranges AND the order of values is reversed.  I am struggling to achieve both at the same time.  Can you help?
> 
> Thanks,
> Naresh
> 
> # Create dummy data for illustration
> my.df <- data.frame(x = runif(100, min = -10, max = -5), name = "A")
> my.df <- rbind(my.df, data.frame(x = rnorm(100), name = "B"))
> my.df <- within(my.df, {y <- x + 0.2 * rnorm(200)})
> 
> # This works.  Both x and y axes show values in reverse order. 
> xyplot(y ~ x, groups = name, data = my.df, xlim = rev(range(my.df$x)), ylim = rev(range(my.df$y)), type = c("p", "g"))
> 
> # This works.  Both x and y axes show values in reverse order. 
> xyplot(y ~ x | name, data = my.df, xlim = rev(range(my.df$x)), ylim = rev(range(my.df$y)), type = c("p", "g"))
> 
> # This does not work as intended.  x and y values are in reverse order.  But both panels have the same and x and y ranges.  scales argument does not seem to have any effect.   
> xyplot(y ~ x | name, data = my.df, xlim = rev(range(my.df$x)), ylim = rev(range(my.df$y)), scales = list(x = "free", y = "free"), type = c("p", "g"))
> 
> # This does not work at all.  panel.xyplot does not see to take xlim or ylim arguments.  

But prepanel does ....

xyplot(y ~ x | name, data = my.df, scales = list(x = "free", y = "free"), panel = function(x,y,subscripts, ...) {
> 	panel.xyplot(x,y, ylim = rev(range(y[subscripts]), xlim = rev(range(x[subscripts]))))
> })

I used this posting to r-help from 2006 by xyplot's author, Sarkar, to solve the problem:

https://stat.ethz.ch/pipermail/r-help/2006-March/101248.html

 xyplot(y ~ x | name, data = my.df, 
    scales =    list(relation="free"),  
    prepanel= function(x,y, ...) { list(xlim=  rev(range(my.df$x)) , 
                                        ylim = rev(range(my.df$y)) )}, 
    type =     c("p", "g"))

-- 
David Winsemius
Alameda, CA, USA