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I have a matrix M > dim(M) [1] 30380   561 I have another list L contains , that contains some row names of matrix M str (L)  chr [1:21037] Now I want to extract the submatrix subM (21037    ,    561)  from the matrix M by matching the rownames (M) to the 21037 rownames o f L How do I do that ? Thanks and regards, Pankaj Barah   Pankaj Barah Department of Biology  Norwegian University