[R] ggplot2 boxplot confusion

[ONKELINX, Thierry]

Chris,

You need to specify position = "identity"

library(ggplot2)
series <- c('C2','C4','C8','C10','C15','C20')
series <- factor(series, levels = series)
ids <- c('ID1','ID2','ID3')
mydata <-
data.frame(SERIES=rep(series,30),ID=rep(ids,60),VALUE=rnorm(180), dummy
= factor(1))
ggplot(mydata, aes(y = VALUE, x = dummy)) + geom_boxplot(position =
"identity") + facet_grid(SERIES ~ ID)

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 op inbo.be 
www.inbo.be 

Do not put your faith in what statistics say until you have carefully
considered what they do not say.  ~William W. Watt
A statistical analysis, properly conducted, is a delicate dissection of
uncertainties, a surgery of suppositions. ~M.J.Moroney

-----Oorspronkelijk bericht-----
Van: r-help-bounces op r-project.org [mailto:r-help-bounces op r-project.org]
Namens Chris Friedl
Verzonden: woensdag 27 februari 2008 23:55
Aan: r-help op r-project.org
Onderwerp: Re: [R] ggplot2 boxplot confusion


Thierry

1.

ggplot(mydata, aes(y = VALUE, x = SERIES)) + geom_boxplot() +
facet_grid(.~
ID)

creates a grid with three ID columns (ID1, ID2, ID3) and six SERIES
columns
within each ID column with two boxplots in each ID column (C10, C2)
(C15,
C4), (C20, C8). I was aiming for a grid with ID columns and SERIES rows.

However if I try something like this:

ggplot(mydata, aes(y = VALUE, x = factor(1))) + geom_boxplot() +
facet_grid(SERIES ~ ID)

I get an error: 

Error: position_dodge requires the following missing aesthetics: x

Yet this works fine for a single boxplot (as you showed previously) if I
remove the facet_grid() command.

Any ideas?

Or perhaps my only recourse is to build this up programmtically, such
as:

(pseudo-ish code)
for id, ser in ids, series:
  dat <- subset(mydata, (id %in% ids & ser %in% series)
  boxplot(dat) in grid position id, ser

Can I specify grid plotting grid by grid with ggplot or do I need to
look at
lattice graphics? (I'd like to stick with ggplot if I can)





ONKELINX, Thierry wrote:
> 
> Chris,
> 
> 1.
> This will make more sense.
> 
> ggplot(mydata, aes(y = VALUE, x = SERIES)) + geom_boxplot() +
> facet_grid(.~ ID) 
> 
> 2.
> Now I think I understand want you want. I'm affraid that won't be easy
> because you're trying to mix continuous variables with categorical
ones
> on the same scale. A density plot has two continuous scales: VALUE and
> it's density. The boxplot has a continuous scale (VALUE) and the other
> is categorical. Maybe Hadley knows a solution for your problem.
> 
> Thierry
> 
> 

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