def delete_vector vector
      raise IndexError, "Vector #{vector} does not exist." unless @vectors.include?(vector)

      @data.delete_at @vectors[vector]
      @vectors = Daru::Index.new @vectors.to_a - [vector]

      self
    end
def delete_vector vector
      raise IndexError, "Vector #{vector} does not exist." unless @vectors.include?(vector)

      @data.delete_at @vectors[vector]
      @vectors = Daru::Index.new @vectors.to_a - [vector]

      self
    end
:nocov:
 Delete a vector