Question

I have looked here: Example code Description

NetLogo project with vector map data

I am using vector map where is roads. Then i draw links where road is. In image where starting point is, that is capital city (Riga) of Latvia. To left side is city Ventspils, witch is about 200 kilometers from Riga. to top is Latvia/Estonia border and also about 200 km. To bottom is about 100 km.

What i want is calculate where i need to place electricity charging station for cars. With average green car can drive 50 kilometers with full battery. So. I know that to Ventspils is about 200 km. We need 4 charging stations on that road.

Idea No 1 is just after every 50 kilometrs to all directions from starting point place charging station. (tree symbols on picture). At this moment charging stations (trees) i am placing at random location:

to setup-stacijas
  set-default-shape boats "tree"
  create-boats num-boats [
    set speed 0 ; min-speed + random-float (max-speed - min-speed)
    let l one-of links
    set size 18
    set-next-stacija-link l [end1] of l
  ]
end 

to set-next-stacija-link [l n] ;; boat proc
  set cur-link l
  move-to n
  ifelse n = [end1] of l [set to-node [end2] of l] [set to-node [end1] of l]
  face to-node
end

Questions:

How i can calculate distance xx kilometers to all directions?

Answer 1

An AGENT (a patch or a turtle) can use the DISTANCE primitive along with the MOD operator to find other AGENTS that are multiples of 50 “miles” away.

I assume that 1 patch = 1 mile in our simulation.
I assume that the “links” are connected to turtles of breed “node”.
I assume that START is a variable that contains a “node”.

;; get all nodes that are multiples of 50 miles from start
let stations no-turtles
ask start [ set stations nodes with [ (floor distance myself) MOD 50 = 0 ]

This isn’t perfect for many reasons.

• It assumes all links are 1 unit or less long.
• Roads that run across or along the arc at 50 miles will ALL be included, so they will ALL have stations.
• Other odd stuff I haven’t thought off.

Some other iterative methods suggest themselves:

1. Setting “travelers” on the roads to “drop” charging stations every 50 (or so) miles.

   • At intersections, traveler splits into new travelers to travel each branch
   • when traveler meets a traveler, if the total distance from each traveler to its last “station” is more than 50 miles, a station is created. In any case, both travelers die.
   • when a traveler finds an existing station, it dies.

   In this way, stations will be placed all along all roads.

2. Fill the patches with stations, in a hex-grid, 25 or something miles in radius. Let them migrate.

   • Make the stations not on roads move toward the nearest road.
   • One all stations have found a road, make stations move away from stations < 50 miles away, moving along roads (break tie by moving away from center of map).
   • stations that hit the edge will “fall off” (die)
   • so, stations will space themselves out, and extra staions will fall off the edges of map.

   This might actually work.

3. Overfil with stations, then destroy until there is only just enough

   • Create a station on every mile of road.
   • pick one station
   • ## ask all other stations in 49 mile radius to die – mark it
   • pick one of the stations 50 miles away.
   • repeat from ## unil all stations are marked.

   That one probably is not optimal.

4. Simulate cars on your roads–create stations where they die.

   • Put cars randomly on your roads (starting from cities). Cars can travel about 50 miles before needing recharge (dying)
   • there are no stations
   • simulate cars driving randomly on the roads.
   • when a car hits a station it recharges fully
   • if a car runs out of charge, it dies, and the counter for that patch/node/location is increased
   • repeat
   • when the counter in a patch exceeds some value, put a station there.
   • when a station is created, the counters for all patches in a 50 mile radius are reduced–to 0 nearest the station, and by 0 furthest, in a gradular fashion.

   Eventually, stations will pop-up where they are needed. This one will be fun to watch.

~~James