I now know that those numbers to the left can be extracted using rowNames(). So how can I extract elements of B where rowNames = rowNames(A)? -- View this message in context: http://r.789695.n4.nabble.com/Extracting-Parts-of-Array-Index-Comparison-tp3753792p3753839.html Sent from the R help mailing list archive at Nabble.com.