ordering a boxplot

There may be more concise ways to do this - but you are 99% there with your approach:
try:

boxplot(mydata[,names(sort(apply(mydata,2,median)))])

B.


On Mar 21, 2015, at 6:49 PM, Antonio Silva <aolinto.lst at gmail.com> wrote:

Thanks Bill and David

Here goes an example

SP1<-c(9,6,7,8,5,8,7,5,9,7)
SP2<-c(1,3,4,2,4,2,5,3,2,1)
SP3<-c(4,6,7,5,7,8,7,6,5,4)
SP4<-c(5,4,3,5,2,3,4,3,4,2)
mydata<-data.frame(SP1,SP2,SP3,SP4)
rownames(mydata)<-c("ST1","ST2","ST3","ST4","ST5","ST6","ST7","ST8","ST9","ST10")
mydata
boxplot(mydata)

Note that this data frame does not have the format Response ~ Group. In my
real matrix I have up to 40 species.

Is there any way to have the species ordered by their median abundance (or
other parameter?)

The desired order is given by names(sort(apply(mydata,2,median)))

Thanks once more,

Antonio Olinto
Fisheries Institute
Sao Paulo, Brazil

2015-03-21 15:13 GMT-03:00 William Dunlap <wdunlap at tibco.com>:

You can use the reorder() function to reorder the grouping vector's
factor levels according to a function of the data in each group.  E.g.,
compare the following two plots:

 d <- data.frame(Response=cos(1:15), Group=rep(c("A","B","C"),c(6,5,4)))
 par(mfrow=c(1,2))
 boxplot(Response ~ Group, data=d)
 boxplot(Response ~ reorder(Group, X=Response, FUN=median), data=d)


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Fri, Mar 20, 2015 at 2:20 PM, Antonio Silva <aolinto.lst at gmail.com>
wrote:

Hello

I'm using a dataframe (mydata) where row names are sampling points and
column names are species in a multivariate analysis.

If I write boxplot(mydata) I'll have boxplots for each species abundance
in
alphabetical order.

How to get the boxes orderer by the median?

Usually for this I write

boxplot(value~category,at=rank(tapply(mydata$value,mydata$category,median)))
but for this to work I need a column for the categories and another column
for the values.

Thanks in advance, best regards.

Antonio Olinto

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