Thank you. Yes, I did look at the help but could not get my expressions to work.

You used a data.frame with thematrix values I gave. Your solution also works when dealing with a matrix (this my be obvious to seasoned R users, but was no to me).

> x<-matrix(c(57,91,31,61,16,84,3,99,85,47,21,6,57,91,31,61,16,84,3,99), ncol=5, byrow=TRUE)
> #order by row
> order(x[,1])
[1] 3 1 4 2
> x[order(x[,1]),]
     [,1] [,2] [,3] [,4] [,5]
[1,]   21    6   57   91   31
[2,]   57   91   31   61   16
[3,]   61   16   84    3   99
[4,]   84    3   99   85   47
> #order by column
> order(x[1,])
[1] 5 3 1 4 2
> x[,order(x[1,])]
     [,1] [,2] [,3] [,4] [,5]
[1,]   16   31   57   61   91
[2,]   47   99   84   85    3
[3,]   31   57   21   91    6
[4,]   99   84   61    3   16
> 
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