[R] simple plot in ggplot2, wrong error bars

[ONKELINX, Thierry]

Dear Beto,

The code below gives a correct result.

library(ggplot2)
df <- data.frame(
	trt = factor(c("intact", "intact", "removed", "removed")),
	coon = c(0.093, 0.06, 0.057, 0.09), 
	group = factor(c("veget", "fruit", "veget", "fruit")), 
	se = c(0.01, 0.01, 0.02, 0.026))
ggplot(df, aes(x=trt, y=coon, fill = group, ymax = coon + se, ymin =
coon - se)) + geom_bar(position = "dodge", stat="identity") +
geom_errorbar(position = "dodge")


------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen
Belgium

Research Institute for Nature and Forest
team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium

tel. + 32 54/436 185
Thierry.Onkelinx op 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 op r-project.org 
> [mailto:r-help-bounces op r-project.org] Namens hpdutra
> Verzonden: vrijdag 12 maart 2010 2:16
> Aan: r-help op r-project.org
> Onderwerp: [R] simple plot in ggplot2, wrong error bars
> 
> 
> I was wondering if anyone  could help me with this, simple problem. 
> 
> I am essentially following the example on Hadley's  webpage
> (http://had.co.nz/ggplot2/geom_errorbar.html), but it still 
> doesn't make any
> sense to me. 
> 
> 
> df <- data.frame(trt = factor(c("intact", "intact", 
> "removed", "removed")),
> coon = c(0.093, 0.06, 0.057, 0.09), group = factor(c("veget", "fruit",
> "veget", "fruit")), se = c(0.01, 0.01, 0.02, 0.026))
>  limits <- aes(ymax = coon + se, ymin=coon - se)
>  p<-ggplot(df, aes(fill=group, y=coon, x=trt))
> p+geom_bar(position="dodge",stat="identity")
> dodge <- position_dodge(width=0.9)
> > p + geom_bar(position="dodge") + geom_errorbar(limits,
> position="dodge",
> > width=0.5)
> 
> as you noticed the code above gets the error bars in the 
> wrong columns. 
> So I used the code below (I replaced position_dodge w/ a 
> negative value and
> geom_errorbarr with dodge no quote marks)
> 
> df <- data.frame(trt = factor(c("intact", "intact", 
> "removed", "removed")),
> coon = c(0.093, 0.06, 0.057, 0.09), group = factor(c("veget", "fruit",
> "veget", "fruit")), se = c(0.01, 0.01, 0.02, 0.026))
> limits <- aes(ymax = coon + se, ymin=coon - se)
> p<-ggplot(df, aes(fill=group, y=coon, x=trt))
> p+geom_bar(position="dodge",stat="identity")
> dodge <- position_dodge(width=-0.9)
> > p + geom_bar(position="dodge") + geom_errorbar(limits,
> position=dodge,
> > width=0.5)
> 
> 
> Why do I need to use negative values to get the right 
> errorbar structure,
> why do I need use doge without quote marks?
> Thanks
> 
> Beto
> 
> 
> 
> -- 
> View this message in context: 
> http://n4.nabble.com/simple-plot-in-ggplot2-wrong-error-bars-t
> p1589994p1589994.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

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