[R] boxplot of subset of factors, in an order of my choice [B roadcast]

[Liaw, Andy]

1. Use something like 

      with(testResults, boxplot(score[test == "rTest"]))

2. testResults$test <- factor(as.character(testResults$test),
                              levels=c("rTest", "gTest", "fTest"))

[Substitute any order you like in the last line.]

Andy

From: Sumitrajit Dhar
> 
> Hi Folks,
> 
> Say I am working with the following data set:
> testResults:
> 	stud		test		score
> 1	1		fTest	43
> 2	1		rTest	39
> 3	1		gTest	43
> 4	2		fTest	23
> 5	2		rTest	33
> 6	2		gTest	41
> .
> .
> .
> N	n		gTest	47
> 
> I would like to generate a boxplot of rTest only. Here is 
> what I have done after reading the data in and attaching the object.
> 
> test <- factor(test)
> 
> Now when I try
> 
> boxplot(score ~ test, subset = test=="rTest")
> 
> 1. I still see the tick marks for the other factors on the 
> x-axis although no data are plotted. Can I eliminate these 
> extra markers (and the space for these faactors) and just 
> have the tick marker and the label for "rTest"?
> 
> 2. I would also like to be able to rearrange the tests as 
> they appear from left to right on the graph. I read the hints 
> and help about reorder.factor but it does not seem to be the 
> solution in this case.  
> I am wanting to re-order the boxes without any logic 
> (statistical anyways). Can this be done?
> 
> Thanks in advance,
> Sumit
> 
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