[R] lattice xyplot: trouble about the use of yscale.components to start the yscale from zero

[Laurent Rhelp]

Thank you very much for the typo !! and the example about the 
consequences.  I did not know about the option warnPartialMatchDollar = 
TRUE, I tested it with my mistake it is very effective indeed. This 
option should be TRUE by default.

I edited my mistake but there is still the trouble, the labels do not 
appear on the y-axis if I keep ylim = c(0,max(lim)). But nevermind 
because your solution to use prepanel works very well and I will think 
next time to use prepanel.

Best regards
L.



Le 22/01/2023 à 18:43, Deepayan Sarkar a écrit :
>
>
> On Sun, Jan 22, 2023 at 6:48 PM Laurent Rhelp <LaurentRHelp using free.fr> 
> wrote:
>
>     Dear RHelp-list,
>
>       I want to choice my scale for every panel in a lattice graph
>     according to
>       the ylim range of every panel, with 10 ticks and with a start
>     from 0.
>     Also I want to plot a grid
>        according to the y ticks (I did that in the panel argument with
>     the
>     panel.abline function) .
>       So I decided to use the yscale.components argument and I write the
>     script below.
>       Before using the pretty function I introduce the 0 value in my
>     range but
>     it does not work : the labels are not displayed and the
>     panel.abline do
>     nothing. I am not able to understand why.
>        If I comment the line ylim <- c(0,max(lim)) the labels appear
>     but of
>     course they do not start from 0.
>
>
> You have mistyped
>
>   ans$left$ticks$at <- tick.at <http://tick.at>
>
> as
>
>   ans$left$tick$at <- tick.at <http://tick.at>
>
> You might think that partial matching will help you, but partial 
> matching doesn't work for assignment (for obvious reasons). Consider
>
> > foo <- list(ticks = list(at = 1:10))
> > foo$tick$at <- "bar"
> > str(foo)
> List of 2
>  $ ticks:List of 1
>   ..$ at: int [1:10] 1 2 3 4 5 6 7 8 9 10
>  $ tick :List of 1
>   ..$ at: chr "bar"
>
> I don't know if there is a good argument for this assignment to work 
> at all (other than that NULL and an empty list are conceptually 
> equivalent), but it is what it is.
>
> This is why I tend to set options(warnPartialMatchDollar = TRUE). In 
> this case it would give you an inaccurate warning, but at least it 
> will give you a warning.
>
> As for the range of the scales, these are determined by 'ylim' and 
> 'prepanel', so you would need to specify one of these.
>
> As you are using scales$axs = "i", you can simply provide ylim = c(0, 
> NA), which forces the lower limit to 0, and lets the upper limit be 
> decided as usual.
>
> For finer control, you can specify a prepanel function, e.g.,
>
> prepanel = function(x, y, ...) list(ylim = c(0, max(y)))
>
> Hope this helps,
>
> Best,
> -Deepayan
>
>
>     Thank you for your help.
>
>     Laurent
>
>
>       --------------------------o<----------------------------------------------->o-----------------------------------------
>     library(lattice)
>     library(zoo)
>     ##
>     ## Rq : mydata is a zoo object
>     ##
>     mydata <- structure(c(0.190991684047867, 0.186639474048368,
>     0.188562286982088,
>                  0.187781290093149, 0.188242724296645, 0.190412570465429,
>     0.188922969182772,
>                  0.194037520889193, 0.191973884842229, 0.197032138922638,
>     1.03204611806177,
>                  1.02831610106898, 1.0280323738983, 1.03595907392095,
>     1.03316162925952,
>                  1.04755124287765, 1.04403986225312, 1.05686325668364,
>     1.04672225664295,
>                  1.05462971668107), dim = c(10L, 2L), dimnames =
>     list(c("f1",
>               "f1", "f1", "f1", "f1", "f1", "f1", "f1", "f1", "f1"),
>     c("col1","col2"))
>               , index = c(1.27904891967773, 1.27909898757935,
>     1.27915000915527
>            , 1.27920007705688, 1.2792489528656, 1.27929902076721,
>     1.27935004234314
>            ,1.27939891815186, 1.27944993972778, 1.27950000762939),
>     class =
>     "zoo")
>
>     options(digits=17)
>
>     yscale.components.n.ticks <- function(lim,...){
>
>        ans <- yscale.components.default(lim = lim,...)
>        ylim <- lim
>        ## I want to start from 0
>        ylim <- c(0,max(lim))
>     tick.at <http://tick.at> <- pretty(ylim, n=10, min.n = 9)
>         cat("lim yscale : ",ylim,"\n")
>
>        mylabels_y <- formatC( tick.at <http://tick.at>
>                               , format = "f"
>                               , digits=3
>                               , width=9
>                               ,flag=" ")
>
>        print(cbind( mylabels_y = mylabels_y, tick.at_y = tick.at
>     <http://tick.at>))
>
>        ans$left$tick$at <- tick.at <http://tick.at>
>        ans$left$labels$at <- tick.at <http://tick.at>
>        ans$left$labels$labels <- mylabels_y
>        ans
>     }
>
>
>     xscale.components.n.ticks <- function(lim, ... ){
>
>        ans <- xscale.components.default(lim = lim,...)
>     tick.at <http://tick.at> <- pretty(lim,20,9)
>        mylabels_x <- formatC( tick.at <http://tick.at>
>                               , format = "f"
>                               , digits=6
>                               , width=9
>                               , flag=" ")
>
>        print(cbind( mylabels_x = mylabels_x, tick.at_x = tick.at
>     <http://tick.at>))
>
>        ans$bottom$tick$at <- tick.at <http://tick.at>
>        ans$bottom$labels$at <- tick.at <http://tick.at>
>        ans$bottom$labels$labels <- mylabels_x
>        ans
>     }
>
>     # to see the x values
>     time(mydata)
>
>     gr <- xyplot(  mydata
>                     , main = "title"
>                     , layout = c(1,2)
>                     , pch = 20
>                     , panel = function(...) {
>
>                       ylim <- current.panel.limits()$ylim
>                       xlim <- current.panel.limits()$xlim
>
>                       ## I create here the same ticks that those created
>                       ##  in xscale.components and yscale.components
>                      ylim <- c(0,max(ylim))
>                      cat("ylim panel : ",ylim,"\n")
>     y.tick.at <http://y.tick.at> <- pretty(ylim,10,9)
>                      print(cbind(y.tick.at.panel= y.tick.at
>     <http://y.tick.at>))
>
>     x.tick.at <http://x.tick.at> <- pretty(xlim,20,9)
>
>                      panel.abline( h = y.tick.at <http://y.tick.at>, v
>     = x.tick.at <http://x.tick.at>, col =
>     "lightgrey")
>
>                       panel.xyplot(...)
>                     }
>     ##               , ylim = c(0,1.5)
>                     , scales = list(
>                       y= list(   relation = "free"
>                                , axs="i"
>                                , rot = 45
>                                ),
>                       x = list(
>                                   axs="i"
>                                 , rot = 90
>                                )
>                     )
>                     , yscale.components = yscale.components.n.ticks
>                     , xscale.components = xscale.components.n.ticks
>
>     )
>
>     print(gr)
>
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