Order a matrix by multiple column in r

Question

I have a matrix

df<-matrix(data=c(3,7,5,0,1,0,0,0,0,8,0,9), ncol=2)
rownames(df)<-c(\"a\",\"b\",\"c\",\"d\",\"e\",\"f\")

[,1] [,2]
a    3    0
b    7          


        

Answer 1

The order function should do it.

df[order(df[,1],df[,2],decreasing=TRUE),]