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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>I’m taking advantage of a feature in data.table which lets me get away with naming columns with characters that would not survive a call to make.names(), e.g.:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> DT1 = data.table(a=letters[1:5], "Illegal(name%)"=1:5, key="a")<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> DT1<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'> a Illegal(name%)<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>1: a 1<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>2: b 2<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>3: c 3<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>4: d 4<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>5: e 5<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>(The the dcast function from the reshape2 package will also create columns named “illegally”.)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>But when using merge.data.table, I get two side-effects; either the merge works, but the column names appear to be run through make.names(), or the merge fails in setcolorder():<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> DT1 = data.table(a=letters[1:5], "Illegal(name%)"=1:5, key="a")<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> DT2 = data.table(a=letters[1:5], b=6L, key="a")<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> merge(DT1,DT2)<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'> a Illegal.name.. b<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>1: a 1 6<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>2: b 2 6<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>3: c 3 6<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>4: d 4 6<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>5: e 5 6<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> merge(DT2,DT1)<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>Error in setcolorder(dt, c(setdiff(names(dt), end), end)) :<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'> neworder is length 4 but x has 3 columns.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>I can’t get to datatable.r-forge.r-project.org – getting a 504.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>So… should I NOT rely on being able to use special characters in column names?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Thanks<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>George<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>> sessionInfo()<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>R version 2.15.0 (2012-03-30)<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>Platform: x86_64-unknown-linux-gnu (64-bit)<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>[1] data.table_1.8.2<o:p></o:p></span></p></div></body></html>