Problems with scatterplot error bars in ggplot2

Question

I have a question about how I can do a scatterplot with error bars. I´m working with stable isotopes so I have data on D13C and D15N for faunal samples. I want to obtain a plot like this one (without convex hulls) attached (target)target.png

But on the contrary I obtain a plot like this (CNPlot)CNPlot.png I´m using this script :

a<-read.table("Means.txt", header = TRUE)
theme_set(theme_classic(base_size = 16))
ggplot(a, aes(x=D13C, y=D15N)) +
geom_errorbar(aes(ymax=D13C+D13C.ds, ymin=D13C-D13C.ds), width=0.15,alpha=.8)+
geom_errorbarh(aes(xmax=D15N+D15N.ds, xmin=D15N-D15N.ds), height=0.15,alpha=.8)+  
  geom_point(aes(shape=Species),fill="white",size=4) +
  geom_point(aes(color=Species,fill=Species,shape=Species),size=4, alpha = .5) +
  scale_color_manual(values=c("black","dodgerblue1","coral4","darkorchid"))+
  scale_fill_manual(values=c("black","dodgerblue1","coral4","darkorchid"))+
  scale_shape_manual(values=c(21,23,22,24))+
 labs(title=NULL,
       subtitle=NULL,
       caption=NULL,
       x=expression(paste(delta^{13}, "Ccol(‰)")),      
       y=expression(paste(delta^{15}, "N(‰)")))

and I have two datasets but I´m using the one named Means but I have another one named CN_fauna where I included the raw data

Means:

Species    D13C    D13C.ds    D15N    D15N.ds
Bird    -16.4    7.1    7.6    1.5
SH    -18.5    1.7    5.5    2.7
CH    -14.8    2.9    8.8    0.6
Deer    -19.2    0.7    4.8    1.04

CN_fauna:

taxa    D13C    D15N
Bird    -24.1    7.9
Bird    -9.9    9
Bird    -15.2    5.9
SH    -17.0    9.6
SH    -16.6    7.3
SH    -20.3    4.6
SH    -20.3    2.6
SH    -20.3    2.7
SH    -18.6    6.6
CH    -16.9    9.4
CH    -11.5    8.2
CH    -16.1    8.8
Deer    -18.6    3.0
Deer    -19.1    6.0
Deer    -18.3    5.4
Deer    -17.9    5.4
Deer    -19.2    5.6
Deer    -20.4    5.6
Deer    -19.5    6.1
Deer    -20.3    5.9
Deer    -18.7    5.4
Deer    -19.7    3.8
Deer    -19.2    3.4
Deer    -19.9    4.1
Deer    -18.4    4.3
Deer    -20.1    4.1

I do not understand why the scales of the error barplots are different in my plot, any help is more than welcome.

Answer 1

Not to take away from the sage advice that @stefan provided (reproducible questions get better responses faster)...

I could be wrong, but I think your errorbar data is on the wrong axis. Is that what you were trying to create?

If so, you need to change your xmin to ymin and so on for the two errorbar layers. It would look something like this:

ggplot(Means, aes(x = D13C, y = D15N)) +
  geom_errorbar(aes(xmax = D13C + D13C.ds, 
                    xmin = D13C - D13C.ds), width=0.15,alpha=.8)+
  geom_errorbar(aes(ymax = D15N + D15N.ds, 
                    ymin = D15N - D15N.ds), height=0.15,alpha=.8)+  
  geom_point(aes(shape=Species),fill="white",size=4) +
  geom_point(aes(color=Species,fill=Species,shape=Species),size=4, alpha = .5) +
  scale_color_manual(values=c("black","dodgerblue1","coral4","darkorchid"))+
  scale_fill_manual(values=c("black","dodgerblue1","coral4","darkorchid"))+
  scale_shape_manual(values=c(21,23,22,24))+
  labs(title=NULL,
       subtitle=NULL,
       caption=NULL,
       x=expression(paste(delta^{13}, "Ccol(‰)")),      
       y=expression(paste(delta^{15}, "N(‰)")))