#sort dataframe by col
sort.df <- with(df, df[order(sortbythiscolumn) , ])
#can also sort by more than one variable: sort by col1 and then by col2
sort2.df <- with(df, df[order(col1, col2) , ])
#sort in reverse order
sort2.df <- with(df, df[order(col1, -col2) , ])