[R] BoxPlot Adding Mean and Median Values

[S Ellison]

> Here is the code I have tried.
The code has to work to be useful.
including the data read - which, because it is on your D: drive, clearly can't be read..

But here are some comments and some base graphics code that should get you started;

> As I mentioned below, would like to add the data labels into each box of mean
> value
	#You'll need to calculate the mean values separately. A standard boxplot doesn't include them

> AmbientTr <- read.csv("AmbientBatchbox.csv", stringsAsFactors = TRUE)
	#Not possible

> str(AmbientTr)
> summary(AmbientTr)
	#Not possible
> install.packages("ggplot2")
	#Don;t need to do this every time
> library(ggplot2)
	#And you don’t need it at all: you are using 'boxplot', which is in base graphics

> boxplot(RTF~Batch,data=AmbientTr, ylim = c(0,30), main="RTF By Batch",
> xlab="Batch", ylab="RTF", col ="blue")
	#Try assigning the result of boxplot to a variable, such as
bw.data <-  boxplot(RTF~Batch,data=AmbientTr, ylim = c(0,30), main="RTF By Batch",
	 xlab="Batch", ylab="RTF", col ="blue")

#Then you csan use that data to place labels etc. because boxplot returns the stats for the boxes, and the locations 
#are (by default) at 1:length()bw.data$names.

#For example, after the above plot:
with(bw.data, text(1:length(names), stats[3,], names, pos=1) #labels just below the medians

#And for placing means on the plot:
RTFmeans <- with(AmbientTr, tapply(RTF, batch, mean))
points(1:length(RTFmeans), RTFmeans, pch=19)
text(1:length(RTFmeans), RTFmeans, paste(round(RTFmeans,0)), pos=3) #labels just above the points 

#... or something like that. 

For a ggplot equivalent, you could try the ggplot mailing list; Google it to find it.

S Ellison


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