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Showing posts from April, 2017

Creating dummy variables in R

Randy Zwitch has a blog entry on creation of dummy variables from factor levels. example <- span=""> as.data.frame ( c ( "A" , "A" , "B" , "F" , "C" , "G" , "C" , "D" , "E" , "F" )) names ( example ) <- span=""> "strcol" #For every unique value in the string column, create a new 1/0 column #This is what Factors do "under-the-hood" automatically when passed to function requiring numeric data for ( level in unique ( example $ strcol )){ example [ paste ( "dummy" , level , sep = "_" )] <- span=""> ifelse ( example $ strcol == level , 1 , 0 ) } view raw Often you encounter special characters in which case you can use gsub and regular expressions example <- span=""> as.data.frame ( c ( "AÆ" , "AÆ" , "B" , "FÅ&quo