SimpleWeightedGraph<String, DefaultWeightedEdge> g = new SimpleWeightedGraph<>(DefaultWeightedEdge.class);
String v1 = "v1";
String v2 = "v2";
String v3 = "v3";
// add the vertices
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
// add edges to create a path
g.addEdge(v1, v2);
g.addEdge(v2, v3);
I use the JGraphT library to create a graph containing a path from v1 to v3 via v2. How can I check if v1 is connected with v3?
Many ways to do it. The way I would use is to check for a shortest path. Just use the following -
DijkstraShortestPath dijk = new DijkstraShortestPath(g, startNode, endNode);
GraphPath<Integer, WeightedEdge> shortestPath = dijk.getPath();
Here g is the graph. The types in GraphPath are the same as that of g. If there is a connection, shortestPath contains the shortest path between them. If not, then shortestPath is equal to null.
Related
i am using a lefleat tile layer with xyz system to query a list of postgis layers,i use a geotools jdbc datastore to fetch layers from database ,but i have to work with bbox or a geotools refernce envelope,how i can transform xyz coordinate to a bbox or a refernce envelope,so i can pass it later to my datastore feature source so i can find geometries or elements in a given bbox ,my coordinate system is EPSG:4326.
You can use the code in gt-tile-client to work with XYZ services.
I think the following should work for you.
String ref = "7/61/53";
String[] parts = ref.split("/");
int z = Integer.valueOf(parts[0]);
int x = Integer.valueOf(parts[1]);
int y = Integer.valueOf(parts[2]);
OSMTile tile = new OSMTile(x, y, new WebMercatorZoomLevel(z), new OSMService("name", "url"));
System.out.println(tile.getExtent());
which gives
ReferencedEnvelope[-8.4375 : -5.625, 27.05912578437406 : 29.535229562948455]
I have an Array of [Long, Q] and would like to make a binary search on it. I tried below :
import scala.collection.Searching._
class Q (val b:Double, val a:Double)
val myArray = Array(5L -> new Q(1,2), 6L-> new Q(6,9), 7L-> new Q(7,6))
val i = myArray.search(6L).insertionPoint
but had this error
No implicit Ordering defined for Any
Unspecified value parameter ord.
I understand that I need to specify an odering rule for this collection Array[(Long,Q)] but can't figure this out myself.
Please help
Signature of search is search[B >: A](elem: B)(implicit ord: Ordering[B]). You've got an array of type [Long, Q]. So in order for the compiler to infer Ordering correctly, you'd have to invoke search like that:
myArray.search(6L-> q/*Q(6,9)*/)(Ordering.by(_._1)) //ordering by the first value in a tuple.
and what you're doing is: myArray.search(6L). If I understand correctly what you're trying to do, it's probably to find both value and position in the array.
You could solve it by using two separate data structures:
keys could be stored in the array, like this:
val myArray = Array(5L, 6L, 7L).toList
myArray.search(6L).insertionPoint
and if you'd need values, you could use map which would work as a dictionary:
val dictionary = Map(
5L -> new Q(1,2),
6L-> new Q(6,9),
7L-> new Q(7,6)
)
EDIT:
Actually, I noticed something like that would work:
val dummy = new Q(0,0) //any instance of Q
myArray.search(6L-> dummy)(Ordering.by(_._1)).insertionPoint //1
It works since for lookup of the insertion point Ordering is used and no equality test is performed.
I am trying to add information from a map received through an http call to a list of objects in Dart. For example, the list of objects are Tools that have the toollocation property:
Tool(
{this.make,
this.model,
this.description,
this.tooltype,
this.toollocation,
this.paymenttype,
this.userid});
I am also using the google distance matrix api to gather the distance from the user that the tool is.
Future<DistanceMatrix> fetchDistances() async {
await getlocation();
latlongdetails = position['latitude'].toString() +
',' +
position['longitude'].toString();
print(latlongdetails);
print('still running');
final apiresponsepc = await http
.get(
'https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins=$latlongdetails&destinations=$postcodes&key=xxx');
distanceMatrix =
new DistanceMatrix.fromJson(json.decode(apiresponsepc.body));
return distanceMatrix;
}
What I have been doing in the past is calling a future and just getting the distance once I have returned the original results for the tool. However I want to be able to sort the tool results by distance, so I need to iterate through each tool in the list and add the distance for each of them.
So far I have been trying a foreach loop on the tools list:
finalresults.forEach((tool){ tool.toollocation = distanceMatrix.elements[0].distance.text;});
but clearly this will only add the first distance measurement to every one of the tools.
Is there any way I can iterate through each tool and then add the distance from the distance matrix map? Each distance will be in sequence with each tool in the list.
I think this is what you wanted to do
finalResults.forEach((tool) {
distanceMatrix.elements.forEach((element){
tool.toolLocation = element.distance.text;
});
});
If elements is also a List then you can use the foreach syntax to iterate through it.
I have resolved this with the following code:
int number = 0;
finalresults.forEach((tool) {
tool.toollocation = distanceMatrix.elements[number].distance.text;
number = number + 1;
});
In the library of the .fla file I have a square exported as Class "cuad" on frame 1
I want to create an Array with 100 squares so as to move them later
So I do like this:
for (var i:uint = 0; i<100;i++)
{
var cuad_mc = new cuad();
addChild(cuad_mc);
myArray.push("cuad_mc");
trace(myArray[i]);
}
I have a runtime error
The error you experience is
Error #1069: Did not find alpha propiety in the String and there is not any value predetermined
The problem comes from your line
myArray.push("cuad_mc");
What you are doing here is pushing a String Object into your Array, not the cuad Object you want. String Objects don't have Alpha values, or x values.
What you want to do is
myArray.push(cuad_mc);
cuad_mc (without the " quotation marks) is a reference to the object you just created.
This should solve your problem. I also recommend using Vectors instead of Array if you only need to store one type of Object. Like this:
var myArray:Vector<cuad> = new Vector<cuad>();
for(var i:int=0;i<100;i++){
var cuad_mc:cuad = new cuad();
addChild(cuad_mc);
myArray.push(cuad_mc);
trace(myArray[i]);
}
Vectors are just like Arrays, but they only allow one specific type, so that a situation like yours doesn't occur.
I have 4 CGPoints that form an irregular figure. How can I rotate that figure 90-degrees and get the new CGPoints?
FWIW, I was able to "fake" this when the figure is a CGRect by swapping origin.x and origin.y, and width and height. Will I need to do something similar (calculating distance/direction between points) or is there a AffineTransform I can apply to a CIVector?
Hints and/or pointers to tutorials/guides welcome.
Skippable Project Background:
Users will take pictures of documents and the app will OCR them. Since users have a great deal of trouble getting a non-skewed image, I allow them to create a 4-point figure around the text body and the app skews that back to a rectangle. The camera images coming in are CIImages and so have their origin already in lower-left, so the 4-point figure must be rotated from the UIView to match...
For the record, I used CGAffineTransforms to rotate the points:
CGAffineTransform t1 = CGAffineTransformMakeTranslation(0, cropView.frame.size.height);
CGAffineTransform s = CGAffineTransformMakeScale(1, -1);
CGAffineTransform r = CGAffineTransformMakeRotation(90 * M_PI/180);
CGAffineTransform t2 = CGAffineTransformMakeTranslation(0, -cropView.frame.size.height);
CGPoint a = CGPointMake(70, 23);
a = CGPointApplyAffineTransform(a, t1);
a = CGPointApplyAffineTransform(a, s);
a = CGPointApplyAffineTransform(a, r);
a = CGPointApplyAffineTransform(a, t2);
&c. for the other points.