       merc_y_s[i] = merc_y
     return [merc_x_s, merc_y_s]
 
-  project_xsys: (xs, ys) ->
+  _project_xsys: (xs, ys) ->
     merc_xs_s = []
     merc_ys_s = []
     for i in [0...xs.length]
-      [merc_x_s, merc_y_s] = @project_xy(xs[i], ys[i])
+      [merc_x_s, merc_y_s] = @_project_xy(xs[i], ys[i])
       merc_xs_s[i] = merc_x_s
       merc_ys_s[i] = merc_y_s
     return [merc_xs_s, merc_ys_s]


    @_map_data()

  project_xy: (x, y) ->
    merc_x_s = []
    merc_y_s = []
    for i in [0...x.length]


    if @plot_model.use_map
      if @_x?
        [@_x, @_y] = @_project_xy(@_x, @_y)
      if @_xs?
        [@_xs, @_ys] = @_project_xsys(@_xs, @_ys)

    if @glglyph?
      @glglyph.set_data_changed(@_x.length)
