Hi again,

one of the little problems when you want to do these travel directions within cities is that the documentation only shows how to calculate TravelDirections between cities and/or landmark buildings.museums etc. For house to house (or street to street) directions you need the exact geolocations of the start and endpoint.

This little function might come in handy:

location[str_String] :=
GeoPosition@(ToExpression[{StringSplit[#, {"<lat>", "</lat>"}][[2]], StringSplit[#, {"<lng>", "</lng>"}][[2]]}] & @
    StringJoin@Flatten@Import["https://maps.googleapis.com/maps/api/geocode/xml?address=" <> StringReplace[str, " " -> "+"]]) 

With it you can enter two addresses as strings like so:

loc1 = location["21 Union Street Aberdeen UK"]; 
loc2 = location["University of Aberdeen UK"];

Then you can -as always- use:

TravelDirections[{loc1, loc2}]["Dataset"]

to get:

Or else:

TravelDirections[{loc1, loc2}]["TravelDistance"]
(*Quantity[1.98282, "Miles"]*)

Cheers,

Marco

Wow! Nicely done using Opacity!! I just made a very similar post here! I was curious about the roads to the city I live in. I really wanted to change the thickness, so it took some more lines of code...

Hi Marco, I'm really sorry to hear that. I should have warn you about the difficulty of rendering 3.96GB of travel directions data in a single GeoGraphics. My suggestion is to decrease the resolution of the GeoPaths. Here is a simple example that tries to find all the travel directions to Rome from all the other capitals of the World. 131 out of 239 capital cities can be reached by car from Rome, being Singapore the capital that takes the longest to reach ( 671220 seconds, almost 8 days driving straight ).

directions=TravelDirections[{CountryData[#,"CapitalCity"],Entity["City",{"Rome","Lazio","Italy"}]}]&/@DeleteCases[CountryData[],Entity["Country","Italy"]];
directions = DeleteCases[directions, _Symbol];
(* Merge the GeoPaths, decrease the resolution by taking a point every 500 points, and color the paths with VertexColors normalized according to the longest travel time: 671220 seconds *)
paths=GeoPath[GeoPosition[pts=Take[Flatten[#["TravelPath"][[1,1]],1],{1,-1,500}]],VertexColors->Table[ColorData["Rainbow"][QuantityMagnitude[#["TravelTime"],"Seconds"]/671220-i/Length[pts]],{i,Length[pts]}]]&/@directions;
(* Render the colored geopaths in GeoGraphics *)
GeoGraphics[{Inset[BarLegend[{"Rainbow",{0,8}},LegendLayout->"Row",LegendLabel->Style["Days",Black,Bold,12],LegendMarkerSize->300],GeoPosition[{-11.45,77.13}]],Thickness[.003],paths,Red,PointSize[.008],Point[Entity["City",{"Rome","Lazio","Italy"}]]},GeoProjection->"Mercator",GeoBackground->GeoStyling["StreetMapNoLabels"],ImageSize->1000]

Attached is the notebook with the colored paths exported as an m file.

Attachments:

Great tip, thanks!

Sander, that's really well-executed! Benoit Mandelbrot would be happy to see that not only nature but human-made roads can generate beautiful fractals.

You might have to use a fast equivalent of GeoDistance, as the earth is curved rather than flat: Norm[{lat1,lon1}-{lat2,lon2}] probably won't give nice results. I'm not sure how to do Voronoi tesselations (quickly) with different norms (Manhattan norm for example).

Hi Marco,

Thanks for the reply; In fact it IS a Voronoi diagram! The measure is just not the usual Euclidean norm, but the a custom norm (TravelDistance)! Given the great profusion of roads throughout Europe, I think the 'normal' Voronoi (using GeoDistance) and custom Voronoi (Using TravelDistance) will be quite the same in those places that are not bordered by masses of water. There is not a lot of CPU necessary right? Memory and internet connection is more crucial I think...

A more general question about TravelDirections: Does it use shortest distance, fastest time, most economic, a mix?