[R] Faceted bar plot shows wrong counts (ggplot2)

[R. Michael Weylandt]

You get the "good" behavior with

base + aes(x = cut) + facet_wrap(~ color, ncol = 5)

so this seems buggy to me.

If someone here doesn't step forward with more insight, I'd forward it
to the ggplot list to see if one of the developers there can give an
explanation or possibly make the official call that it's a bug.

There was another report of a possible bug in facet_grid() today that
could be related:
https://groups.google.com/group/ggplot2/browse_thread/thread/5213ac35da6b36d4

Michael

On Mon, Mar 12, 2012 at 7:16 AM, Helios de Rosario
<helios.derosario at ibv.upv.es> wrote:
> I have encountered a problem with faceted bar plots. I have tried to
> create something like the example explained in the ggplot2 book (see pp.
> 126-128):
>
> library(ggplot2)
> mpg4  <-  subset(mpg,  manufacturer  %in%
> c("audi",  "volkswagen",  "jeep"))
> mpg4$manufacturer  <-  as.character(mpg4$manufacturer)
> mpg4$model  <-  as.character(mpg4$model)
>
> base  <-  ggplot(mpg4,  aes(fill  =  model))  +
> geom_bar(position  =  "dodge")  +
> opts(legend.position  =  "none")
> base  +  aes(x  =  model)  +
> facet_grid(.  ~  manufacturer)
>
> That example works fine; the bar heights are just the same as the
> counts in the table:
>
> table(mpg4[,1:2])
>          model
> manufacturer a4 a4 quattro a6 quattro grand cherokee 4wd gti jetta new
> beetle
>  audi        7          8          3                  0   0     0
>    0
>  jeep        0          0          0                  8   0     0
>    0
>  volkswagen  0          0          0                  0   5     9
>    6
>          model
> manufacturer passat
>  audi            0
>  jeep            0
>
> But in other cases this does not occur. For instance, take a small
> subset of data(diamonds):
>
> diamonds25 <- droplevels(diamonds[1:25,2:3])
> table(diamonds25)
>           color
> cut         E F H I J
>  Fair      1 0 0 0 0
>  Good      1 0 0 1 4
>  Very Good 1 0 3 1 4
>  Premium   3 1 0 1 0
>  Ideal     1 0 0 1 2
>
> And change the variables mapped in the previous plot:
>
> base  <-  ggplot(diamonds25,  aes(fill  =  cut))  +
> geom_bar(position  =  "dodge")  +
> opts(legend.position  =  "none")
> base  +  aes(x  =  cut)  +
> facet_grid(.  ~  color)
>
> I see all bars with height = 1.
> I have ovserved this problem (wrong bar heights, but not always = 1),
> in other cases when all counts are very small or zero.
> What's wrong here?
>
> Regards,
> Helios
>
> sessionInfo()
> R version 2.14.2 (2012-02-29)
> Platform: i386-pc-mingw32/i386 (32-bit)
>
> locale:
> [1] LC_COLLATE=Spanish_Spain.1252  LC_CTYPE=Spanish_Spain.1252
> [3] LC_MONETARY=Spanish_Spain.1252 LC_NUMERIC=C
> [5] LC_TIME=Spanish_Spain.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] ggplot2_0.9.0
>
> loaded via a namespace (and not attached):
>  [1] colorspace_1.1-1   dichromat_1.2-4    digest_0.5.1
> grid_2.14.2
>  [5] MASS_7.3-17        memoise_0.1        munsell_0.3
> plyr_1.7.1
>  [9] proto_0.3-9.2      RColorBrewer_1.0-5 reshape2_1.2.1
> scales_0.2.0
> [13] stringr_0.6
>
>
>
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