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rdataframematrixsubset

I have a subset matrix extracted from a data frame, how can I get the corresponding row names?

A=data.frame(Lat=(1:5),long=(6:10))
rownames(A)<-c("a","b","c","d","e")
B=matrix(c(2,7,4,9),nrow=2,ncol=2, byrow=TRUE)

How can I get the corresponding row names "b" and "d" for matrix B from data frame A?

Solution

  • You can use the function row.match in the package prodlim, which is very easy to use. It returns a vector with the row numbers of (first) matches and NA otherwise. You can use that vector (m in this example) to identify the rownames of A for which a match was found in B. 

    library(prodlim)
m <- row.match(A, B)
rownames(A)[!is.na(m)]
#[1] "b" "d"