prof brian ripley ripleystatsoxacuk wed 6 aug 2008 faheem mitha wrote hi consider following x c12 c34 dataframecbindxy dx 1 1 2 dx 1 1 2 foo functionval returndval bar function returndx foox null bar 1 1 2 im little surprised r accepts form dx dx im mostly wondering foox doesnt work work returns dval instructed help usage xname name literal character string name possibly backtick quoted see version dataframe little surprised function works described help page please explain us conclusion think looking help page thanks faheem brian ripley ripleystatsoxacuk professor applied statistics httpwwwstatsoxacukripley university oxford tel 44 1865 272861 self 1 south parks road 44 1865 272866 pa oxford ox1 3tg uk fax 44 1865 272595 ______________________________________________ rhelprprojectorg mailing list httpsstatethzchmailmanlistinforhelp please read posting guide httpwwwrprojectorgpostingguidehtml provide commented minimal selfcontained reproducible code wed 06 aug 2008 173935 0100 r subsetting column name string