[R] lattice: how to use a log scale on the x-axis with the bwplot function

[Deepayan Sarkar]

On Sun, Dec 11, 2022 at 11:05 PM Laurent Rhelp <LaurentRHelp using free.fr> wrote:
>
> Excellent, it works.
>
> But, may you please explain me how xyplot knows that it has to apply
> panel.bwplot on every groups according to the groups factor ? Because
> there is only one panel. I introduced the groups argument in order to
> apply the bwplot function only on the values of every group.

xyplot() doesn't know that, but panel.bwplot() does. It chooses one of
the variables as the grouping variable (depending on
horizontal=TRUE|FALSE); see ?panel.bwplot.

Best,
-Deepayan

>
>
> Le 11/12/2022 à 17:48, Deepayan Sarkar a écrit :
> > On Sun, Dec 11, 2022 at 2:33 PM Laurent Rhelp <LaurentRHelp using free.fr> wrote:
> >> I understand the idea but I did not succeed.
> >>
> >> Here is what I tried:
> >>
> >> ## 1.    middles of classes calculation
> >>
> >> m <- tapply(DF$x, groups, mean)
> >>
> >> ## 2.     create a new factor columns with the levels deduced from
> >> ##         the values of the middles of the classes
> >> ##
> >>
> >> DF$m <- DF$groups
> >> levels(DF$m) <- as.character(m)
> >> DF$m <- as.numeric(levels(DF$m))[DF$m]
> >>
> >> ## 3. I verify with xyplot
> >>
> >> xyplot(   y ~ m
> >>             , type = "p"
> >>             , data=DF
> >>             , scales = list(
> >>               y = list(log=T)
> >>               , x = list(log=T)
> >>
> >>             )
> >> )
> >> ## 4. I use the panel.groups and panel.bwplot to display the boxplots
> >> without success
> >>
> >> xyplot(   y ~ m
> >>             , groups = groups
> >>             , type = "p"
> >>             , data=DF
> >>             , scales = list(
> >>               y = list(log=T)
> >>               , x = list(log=T)
> >>               , panel = panel.superpose
> >>               ,  panel.groups=function(x,y, group.number,...){
> >>                 panel.xyplot(x,y,...)
> >>                 panel.bwplot(x,y,...)
> >>               }
> >>               , horizontal = FALSE
> >>               , box.width = .0001
> >>             )
> >> )
> > You have a typo here: x = list(log=T) should be followed by a
> > close-paren to complete scales.
> >
> > But I don't understand from your specification why you need groups and
> > panel.superpose etc. What is wrong with
> >
> > xyplot( y ~ m
> >       ## , groups = groups # why?
> >       , data=DF
> >       , scales = list(
> >             y = list(log=T)
> >           , x = list(log=T)
> >         )
> >       , panel = panel.bwplot
> >       , horizontal = FALSE
> >       , box.width = .0001
> >         )
> >
> > ?
> >
> > And sorry for my wrong calculation of m earlier, but you can simplify
> > your version to
> >
> > m <- tapply(DF$x, groups, mean)
> > DF$m <- as.vector(m[DF$groups])
> >
> > Best,
> > -Deepayan
> >
> >>
> >> thx
> >>
> >>
> >>
> >> Le 10/12/2022 à 17:02, Deepayan Sarkar a écrit :
> >>> Log-scales for the "factor" variable in bwplot() is not allowed.
> >>>
> >>> You could, however, use the panel function panel.bwplot() with
> >>> xyplot(num ~ num). The potential problem with that is the box widths,
> >>> which panel.bwplot() will not know how to compute.
> >>>
> >>> See if the following gives you a reasonable starting point:
> >>>
> >>> DF <- within(DF, m <- tapply(y, groups, mean))
> >>> xyplot(y ~ m, DF, scales = list(log = TRUE),
> >>>          panel = panel.bwplot, horizontal = FALSE,
> >>>          box.width = .0001)
> >>>
> >>> Best,
> >>> -Deepayan
> >>>
> >>> On Sat, Dec 10, 2022 at 7:46 PM Laurent Rhelp <LaurentRHelp using free.fr> wrote:
> >>>> Dear R-Help list,
> >>>>
> >>>>       I would like to use bwplot from the lattice package with a log scale
> >>>> both on
> >>>> the x-axis and the y-axis but I do not know how to do that because I do
> >>>> not know
> >>>> how to change the factor x-axis in a numeric x-axis.
> >>>>
> >>>>     Here is my example:
> >>>>
> >>>>
> >>>> library(lattice)
> >>>>
> >>>> # the mock data
> >>>> y <- runif(100000,min=0, max=500)
> >>>> x <- seq(0,500,length=length(y))
> >>>> # I cut the x variable to create a factor variable in order to calculate
> >>>> the boxes
> >>>> groups <- cut(x,10,ordered_result = TRUE)
> >>>> # creating the dataframe for the lattice functions
> >>>> DF <- data.frame( x= x , y = y, groups = groups)
> >>>>
> >>>>
> >>>> ## ok for xyplot
> >>>> xyplot(   y ~ x
> >>>>              , data=DF
> >>>>              , scales = list(
> >>>>                y = list(log=T)
> >>>>                , x = list(log=T)
> >>>>
> >>>>              )
> >>>> )
> >>>>
> >>>> ## ok for bwplot with the log scale for the y-axis
> >>>> bwplot( y ~ groups
> >>>>              , data=DF
> >>>>              , scales = list(
> >>>>                y = list(log=T)
> >>>>                #     , x = list(log=T)
> >>>>
> >>>>              )
> >>>> )
> >>>>
> >>>>
> >>>>
> >>>> ## Non ok for bwplot with the log scale for the x-axis
> >>>> bwplot( y ~ groups
> >>>>            , data=DF
> >>>>            , scales = list(
> >>>>                  y = list(log=T)
> >>>>                , x = list(log=T)
> >>>>
> >>>>            )
> >>>> )
> >>>> which gives an error because the x-axis is a factor, I would like to
> >>>> replace it
> >>>> for the display by the meddle of every class for example and put a log
> >>>> scale on the x-axis.
> >>>>
> >>>> Thank you for your help
> >>>> Best regards
> >>>> Laurent
> >>>>
> >>>>
> >>>>
> >>>> --
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> >>>>
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> >>
> >>
> >> --
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>
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