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

[Laurent Rhelp]

Ok for the labels but the x-axis is not displayed in log scale ?



Le 10/12/2022 à 22:36, Bert Gunter a écrit :
> ... and here's a version where the x variable is different than y. 
> It's basically the same.
>
>
> set.seed(123)
> y <- runif(40,min=0, max= 10)
> x <- seq(0,10, length = 40)
> ## 5 equally spaced groups labeled by log10 of the center
> ## of the intervals
> xrng <- range(x)
> eps <- .0001*c(-1,1)*diff(xrng) ## see ?cut
> xrng <-xrng + eps
> delta <- diff(xrng)/5 # 5 = number of intervals
> brks <- seq(xrng[1], xrng[2],length.out =6)
> labs <- round(log10(brks[-1] - delta/2), 2) ## log10 (centers)
> groups <- cut(x,breaks = brks, ordered_result = TRUE,
>               labels = paste0('10^',labs))
> # creating the dataframe for the lattice functions
> DF <- data.frame( y = y, groups = groups)
>
> bwplot( y ~ groups
>         , data=DF
>         , scales = list(
>            y = list(log=T)
>         ),
> )
>
> On Sat, Dec 10, 2022 at 10:20 AM Bert Gunter <bgunter.4567 using gmail.com> 
> wrote:
>
>     If Deepayan's suggestion does not suit and especially *if* I
>     understand what you want to do correctly, then it seems to me that
>     it is straightforward to create the groups and group labels manually:
>
>     ## in verbose detail to hopefully improve clarity
>     set.seed(123) ## for reprex
>     y <- runif(40,min=0, max= 10)  ##*small* reprex
>     ## cut y into 5 equally spaced groups labeled by log10 of the center
>     ## of the intervals
>     yrng <- range(y)
>     eps <- .0001*c(-1,1)*diff(yrng) ## see ?cut
>     yrng <-yrng + eps
>     delta <- diff(yrng)/5 # 5 = number of intervals
>     brks <- seq(yrng[1], yrng[2],length.out =6)
>     labs <- round(log10(brks[-1] - delta/2), 2) ## log10 (centers)
>     groups <- cut(y,breaks = brks,
>                   labels = paste0('10^',labs))
>     # creating the dataframe for the lattice functions
>     DF <- data.frame( y = y, groups = groups)
>
>     bwplot( y ~ groups
>             , data=DF
>             , scales = list(
>                y = list(log=T)
>             ),
>     )
>
>     ## Of course, ignore if I have misunderstood.
>
>     Cheers,
>     Bert
>
>     On Sat, Dec 10, 2022 at 8:03 AM Deepayan Sarkar
>     <deepayan.sarkar using gmail.com> wrote:
>
>         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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>
>         ______________________________________________
>         R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>         https://stat.ethz.ch/mailman/listinfo/r-help
>         PLEASE do read the posting guide
>         http://www.R-project.org/posting-guide.html
>         <http://www.R-project.org/posting-guide.html>
>         and provide commented, minimal, self-contained, reproducible code.
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