Example #1
0
// Take the list of station locations and fold them into the regions of a grid.
func BuildGrid(locs []*StationLoc, zips []*Zip, r image.Rectangle, c *GridConfig) *Grid {
	nx, ny := c.W, c.H
	regs := make([][]*Region, nx)
	for i := 0; i < nx; i++ {
		regs[i] = make([]*Region, ny)
	}

	// create all active rectangles
	for _, xy := range c.Active {
		i, j := xy[0], xy[1]
		regs[i][j] = &Region{
			I:    i,
			J:    j,
			Rect: image.Rect(i*c.Size, j*c.Size, (i+1)*c.Size, (j+1)*c.Size),
		}
	}

	// assign stations to their region
	for _, loc := range locs {
		ix, iy := int(loc.X/float64(c.Size)), int(loc.Y/float64(c.Size))
		r := regs[ix][iy]
		if r == nil {
			continue
		}
		r.Stations = append(r.Stations, loc)
	}

	// assign zips to their region
	for _, zip := range zips {
		ix, iy := int(zip.X/float64(c.Size)), int(zip.Y/float64(c.Size))
		if ix >= c.W || ix < 0 || iy >= c.H || iy < 0 {
			continue
		}
		r := regs[ix][iy]
		if r == nil {
			continue
		}
		r.Zips = append(r.Zips, zip)
	}

	grid := &Grid{
		W:    nx,
		H:    ny,
		Grid: regs,
	}

	for _, xy := range c.Active {
		i, j := xy[0], xy[1]
		regs[i][j].Nearest = NearestN(c, grid, regs[i][j], 20)
		city := LabelFor(grid, i, j)
		regs[i][j].City = city
	}

	return grid
}