line2route with unroutable lines about stplanr HOT 4 CLOSED

This would slow down line2route. It already fails well and indicates so in the data. I suggest creating a function that can re-route straight lines generated by line2route using a snap to route algorithm. Note that I tested CycleStreets.net's 'snap to route' algorithm and found it is already used internally so instead we should use another one, e.g. Google's or OSRM's, both of which are documented in stplanr I believe.

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I would suggest a wrapper script around line2route that runs the process you suggest. You would then get a function that does:

1. Call line2route normally
2. Select a subset of the SpatialLinesDataFrame that contains only the routes that failed in the initial call.
3. Snap each of the coordinates to the nearest point on the route network using another algorithm
4. Run line2route with the subset with updated coordinates
5. Replace the failed routes with the new ones.

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Sounds like a good suggestion @richardellison I'm up for giving it a bash. We need it anyway for our work. (Context: @nikolai-b is working on the development of the Propensity to Cycle Tool for which line2route was originally written.)

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First I wanted to check if this has been fixed upstream
Here is a csv file (github wanted me to rename it as a text file...) with the points that were failing and now Cyclestreets seems able to route them.

Looks like it has been fixed upstream!

Ruby code used to check the newer nearest point api:

require 'httparty'
require 'rgeo/geo_json'

class CycleStreetNearest
  include HTTParty
  base_uri 'https://api.cyclestreets.net/'
  attr_reader :token, :dir

  def initialize(token = ENV['CYCLESTREET'], dir = 'data-sources')
    @token, @dir = token, dir
  end

  def query
    file = File.read(File.join(dir, "failing-points.geojson"))
    unsnappable = RGeo::GeoJSON.decode(file, json_parser: :json)
    nearestpoints = unsnappable.map do |feature|
      lng = feature.geometry.x
      lat = feature.geometry.y
      [feature.properties['geo_code'], lng, lat] + api_call(lng, lat)
    end
    CSV.open(File.join(dir, "snapped.csv"), "wb") do |csv|
      nearestpoints.each { |point| csv << point }
    end
  end

  private

  def api_call(lng, lat)
    self.class.get('/v2/nearestpoint', query: {
      key: token,
      lonlat: "#{lng},#{lat}"
    })['features'][0]['geometry']['coordinates']
  end
end

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