Returns a duplicate table object, in column mode. This is handy for chaining in a single call without changing the table mode, but be aware that this method can consume a fair amount of memory for bigger data sets.
This method returns the duplicate table for chaining. Don’t chain destructive methods (like =()) this way though, since you are working with a duplicate.
# File lib/csv.rb, line 564 def by_col self.class.new(@table.dup).by_col! end