[R] ggplot2: proper use of facet_grid inside a function

[baptiste auguie]

Hi,

Whether or not what follows is to be recommended I don't know, but it
seems to work,

p <- ggplot(diamonds, aes(carat, ..density..)) +
  geom_histogram(binwidth = 0.2)

x = quote(cut)
facets = facet_grid(as.formula(bquote(.~.(x))))
p + facets

HTH,

baptiste

2009/10/5 Bryan Hanson <hanson at depauw.edu>:
> Thanks Thierry for the work-around.  I was out of ideas.
>
> I had looked around for the facet_grid() analog of aes_string(), and
> concluded there wasn't one.  The only thing I found was the notion of
>
> facet_grid("...") but apparently it is intended for some other use, as it
> doesn't work as I thought it would (like a hypothetical
> facet_grid_string()).
>
> Thanks so much.  Bryan
>
>
> On 10/5/09 4:12 AM, "ONKELINX, Thierry" <Thierry.ONKELINX at inbo.be> wrote:
>
>> Dear Bryan,
>>
>> In the ggplot() function you can choose between aes() and aes_string().
>> In the first you need to hardwire the variable names, in the latter you
>> can use objects which contain the variable names. So in your case you
>> need aes_string().
>>
>> Unfortunatly, facet_grid() works like aes() and not like aes_string().
>> That is why you are getting errors.
>>
>> A workaround would be to add a dummy column to your data.
>>
>> library(ggplot2)
>> data <- mpg
>> fac1 <- "cty"
>> fac2 <- "drv"
>> res <- "displ"
>> data$dummy <- data[, fac2]
>> ggplot(data, aes_string(x = fac1, y = res)) + geom_point() +
>> facet_grid(.~dummy)
>>
>> HTH,
>>
>> Thierry
>>
>>
>> ------------------------------------------------------------------------
>> ----
>> ir. Thierry Onkelinx
>> Instituut voor natuur- en bosonderzoek / Research Institute for Nature
>> and Forest
>> Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
>> methodology and quality assurance
>> Gaverstraat 4
>> 9500 Geraardsbergen
>> Belgium
>> tel. + 32 54/436 185
>> Thierry.Onkelinx at inbo.be
>> www.inbo.be
>>
>> To call in the statistician after the experiment is done may be no more
>> than asking him to perform a post-mortem examination: he may be able to
>> say what the experiment died of.
>> ~ Sir Ronald Aylmer Fisher
>>
>> The plural of anecdote is not data.
>> ~ Roger Brinner
>>
>> The combination of some data and an aching desire for an answer does not
>> ensure that a reasonable answer can be extracted from a given body of
>> data.
>> ~ John Tukey
>>
>> -----Oorspronkelijk bericht-----
>> Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
>> Namens Bryan Hanson
>> Verzonden: vrijdag 2 oktober 2009 17:21
>> Aan: <R Help
>> Onderwerp: [R] ggplot2: proper use of facet_grid inside a function
>>
>> Hello Again R Folk:
>>
>> I have found items about this in the archives, but I'm still not getting
>> it right.  I want to use ggplot2 with facet_grid inside a function with
>> user specified variables, for instance:
>>
>>     p <- ggplot(data, aes_string(x = fac1, y = res)) + facet_grid(. ~
>> fac2)
>>
>> Where data, fac1, fac2 and res are arguments to the function.  I have
>> tried
>>
>>     p <- ggplot(data, aes_string(x = fac1, y = res)) + facet_grid(. ~
>> as.name(fac2))
>>
>> and
>>
>>     p <- ggplot(data, aes_string(x = fac1, y = res)) + facet_grid(". ~
>> fac2")
>>
>> But all of these produce the same error:
>>
>> Error in `[.data.frame`(plot$data, , setdiff(cond, names(df)), drop =
>> FALSE) :
>>   undefined columns selected
>>
>> If I hardwire the true identity of fac2 into the function, it works as
>> desired, so I know this is a problem of connecting the name with the
>> proper value.
>>
>> I'm up to date on everything:
>>
>> R version 2.9.2 (2009-08-24)
>> i386-apple-darwin8.11.1
>>
>> locale:
>> en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
>>
>> attached base packages:
>> [1] grid      datasets  tools     utils     stats     graphics
>> grDevices methods
>> [9] base
>>
>> other attached packages:
>>  [1] Hmisc_3.6-0        ggplot2_0.8.3      reshape_0.8.3
>> proto_0.3-8
>>  [5] mvbutils_2.2.0     ChemoSpec_1.1      lattice_0.17-25
>> mvoutlier_1.4
>>  [9] plyr_0.1.8         RColorBrewer_1.0-2 chemometrics_0.4   som_0.3-4
>>
>> [13] robustbase_0.4-5   rpart_3.1-45       pls_2.1-0          pcaPP_1.7
>>
>> [17] mvtnorm_0.9-7      nnet_7.2-48        mclust_3.2
>> MASS_7.2-48
>> [21] lars_0.9-7         e1071_1.5-19       class_7.2-48
>>
>> loaded via a namespace (and not attached):
>> [1] cluster_1.12.0
>>
>> Thanks for any help!  Bryan
>> *************
>> Bryan Hanson
>> Professor of Chemistry & Biochemistry
>> DePauw University, Greencastle IN USA
>>
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