以下 PiP 搜索是为一个项目构建的，该项目允许用户通过地址或纬度/经度 ( http://staging.placeanddisplaced.org ) 找到他们的纽约市政府区。它可以工作，但有点慢，尤其是在搜索具有复杂多边形的区域时。谁能给我一些关于优化此代码的建议？
我的一个想法是运行 point_in_polygon？每个多边形的简化版本上的方法，即更少的坐标。这意味着更少的处理时间，但也降低了准确性..想法？
class DistrictPolygonsController < ApplicationController
def index
...
if coordinates?
@district_polygons = DistrictPolygon.
coordinates_within_bounding_box(params[:lat], params[:lng]).
find(:all, :include => :district, :select => select).
select { |dp| dp.contains_coordinates?(params[:lat], params[:lng]) }
else
@district_polygons = DistrictPolygon.find(:all, :include => :district, :select => select)
end
...
end
end
class DistrictPolygon < ActiveRecord::Base
named_scope :coordinates_within_bounding_box, lambda { |lat,lng| { :conditions => ['min_lat<? AND max_lat>? AND min_lng<? AND max_lng>?', lat.to_f, lat.to_f, lng.to_f, lng.to_f] } }
named_scope :with_district_type, lambda { |t| { :conditions => ['district_type=?', t] } }
before_save :get_bounding_box_from_geometry
def get_bounding_box_from_geometry
# return true unless self.new_record? || self.geometry_changed? || self.bounds_unknown?
self.min_lat = all_lats.min
self.max_lat = all_lats.max
self.min_lng = all_lngs.min
self.max_lng = all_lngs.max
true # object won't save without this return
end
def bounds_unknown?
%w(min_lat max_lat min_lng max_lng).any? {|b| self[b.to_sym].blank? }
end
def bounds_known?; !bounds_unknown?; end
# Returns an array of XML objects containing each polygons coordinates
def polygons
Nokogiri::XML(self.geometry).search("Polygon/outerBoundaryIs/LinearRing/coordinates")
end
def multi_geometric?
Nokogiri::XML(self.geometry).search("MultiGeometry").size > 0
end
# Returns an array of [lng,lat] arrays
def all_coordinates
pairs = []
polygons.map do |polygon|
polygon.content.split("\n").map do |coord|
# Get rid of third 'altitude' param from coordinate..
pair = coord.strip.split(",")[0..1].map(&:to_f)
# Don't let any nils, blanks, or zeros through..
pairs << pair unless pair.any? {|point| point.blank? || point.zero? }
end
end
pairs
end
# All latitudes, regardless of MultiPolygonal geometry
def all_lats
all_coordinates.map(&:last).reject{|lat| lat.blank? || lat.zero?}
end
# All longitudes, regardless of MultiPolygonal geometry
def all_lngs
all_coordinates.map(&:first).reject{|lng| lng.blank? || lng.zero?}
end
# Check to see if coordinates are in the rectangular bounds of this district
def contains_coordinates?(lat, lng)
return false unless coordinates_within_bounding_box?(lat.to_f, lng.to_f)
polygons.any? { |polygon| DistrictPolygon.point_in_polygon?(all_lats, all_lngs, lat.to_f, lng.to_f) }
end
def coordinates_within_bounding_box?(lat, lng)
return false if (max_lat > lat.to_f == min_lat > lat.to_f) # Not between lats
return false if (max_lng > lng.to_f == min_lng > lng.to_f) # Not between lngs
true
end
# This algorithm came from http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
def self.point_in_polygon?(x_points, y_points, x_target, y_target)
num_points = x_points.size
j = num_points-1
c = false
for i in 0...num_points do
c = !c if ( ((y_points[i]>y_target) != (y_points[j]>y_target)) && (x_target < (x_points[j]-x_points[i]) * (y_target-y_points[i]) / (y_points[j]-y_points[i]) + x_points[i]) )
j = i
end
return c
end
end