def from_activerecord(relation, *fields)
        fields = relation.klass.column_names if fields.empty?
        fields = fields.map(&:to_sym)

        result = relation.pluck(*fields).transpose
        Daru::DataFrame.new(result, order: fields).tap(&:update)
      end
Load dataframe from AR::Relation

@param relation [ActiveRecord::Relation] A relation to be used to load the contents of dataframe

@return A dataframe containing the data in the given relation