How to get row index number for particular name(s)?

r rows rowname
Roger picture Roger · Dec 18, 2013 · Viewed 11.5k times · Source

How can one determine the row index-numbers corresponding to particular row names? I have a vector of row names, and I would like to use these to obtain a vector of the corresponding row indices in a matrix.

I tried row() and as.integer(rownames(matrix.object)), but neither seems to work.

Answer

A5C1D2H2I1M1N2O1R2T1 picture A5C1D2H2I1M1N2O1R2T1 · Dec 18, 2013

In addition to which, you can look at match:

m <- matrix(1:25, ncol = 5, dimnames = list(letters[1:5], LETTERS[1:5]))
vec <- c("e", "a", "c")
match(vec, rownames(m))
# [1] 5 1 3

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