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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Not sure whether the following is an intended behavior with data.table. Perhaps it is something idiosyncratic with factors.<o:p></o:p></p><p class=MsoNormal>It is different than what one gets with data.frame<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.df <- data.frame(X=letters[1:10], Y=rnorm(10))<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.dt <- data.table(X=letters[1:10], Y=rnorm(10))<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.df$X <- "Something Different"<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.dt$X <- "Something Different"<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'>Error in `[<-.data.table`(x, j = name, value = value) : <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'> Some or all RHS not present in factor column levels<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.df <- data.frame(X=letters[1:10], Y=rnorm(10))<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.dt <- data.table(X=letters[1:10], Y=rnorm(10))<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.df[["X"]] <- "Something Different"<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>test.dt[["X"]] <- "Something Different"<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal>Damian Betebenner<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal>Center for Assessment<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal>PO Box 351<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal>Dover, NH 03821-0351<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal><span style='color:navy'> <o:p></o:p></span></p><p class=MsoNormal>Phone (office): (603) 516-7900<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal>Phone (cell): (857) 234-2474<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal>Fax: (603) 516-7910<span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal><span style='color:navy'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:navy'><a href="mailto:dbetebenner@nciea.org"><span style='color:blue'>dbetebenner@nciea.org</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:navy'><a href="http://www.nciea.org/"><span style='color:blue'>www.nciea.org</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:navy'><o:p> </o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>