I am trying to use traverse to explore multiple orders of edges away from a specific starting node. For example, using the Grateful Dead graph, I call this command:
traverse bothE('followed_by') from #15:8 while $depth<3
I expect this to get two orders of edges. However, all the edges are ones that include the starting node. If instead I use both('followed_by') it appears to visit all the desired vertices, but it doesn't report the edges. What should I do?
The in edge on #15:8 record is called followed_by, and the out are sung_by, written_by, followed_by, so you can't use followed_by name and get also out edges, even if you use both in your query:
This one should do it:
traverse bothE() from #15:8 while $depth<3
Related
In this example I select two rectangular nodes in order to copy and paste it.When i do it, the order of the nodes is not correct (see figure).How do i put them sequentially and automatically(node1,node2,node3,mode4)? thanks
If you want to have a sequential list of any object, you put them into a LinkedList.
In your case, have a LinkedList<Node> or use an AnyLogic "Collection" element, set it to LinkedList and the object type to Node.
Then, check how they work, it is standard Java stuff (independent of AnyLogic). QUite useful data type :)
I have a query which returns a number of ways. I want to find nodes matching certain criteria which appear within those ways. Note that the nodes I'm interested in do not form part of the way itself, but do appear within the bounds of the way. Also, the ways do not all have corresponding areas, so using the area search doesn't work in all cases.
I've got a minimal example which finds way 95677318, and I want to be able to find node 1552949334:
(
way({{bbox}})["man_made"="lighthouse"];
)->.searchArea;
/*doesn't work:*/
/*node(area.searchArea)["seamark:name"];*/
/*recur down and find node directly, just for the purpose of this question*/
(
.searchArea;>;
node({{bbox}})["seamark:name"];
);
out;
(Try it on https://overpass-turbo.eu/s/EpV)
This feature is not yet available as of release 0.7.55. In case there's no corresponding area available on the Overpass server, this kind of query is simply not feasible.
See https://github.com/drolbr/Overpass-API/issues/77 for details.
I created an HasAddress edge between an User and an Address vertex.
If I remove the HasAddress edge, the User vertex still shows the HasAddress connection, just empty.
Any way of removing it? Is this just a GUI thing?
this doesn't seem to work UPDATE User REMOVE HasAddress
It's not properly a GUI thing, but you can ignore it.
When you create an edge and connect it to a vertex, OrientDB creates a collection of links (a RIDBAG) as a property of the vertex. When you delete edges, the edge pointer is removed from the collection, but the collection itself is not removed.
If you really don't like that, you can run an
UPDATE User REMOVE in_HasAddress
/* or out_HasAddress if you want to remove the outgoing edges collection */
but PLEASE, make sure that the collections are EMPTY, otherwise you will break the graph consistency (you are using a document API to manipulate the graph).
My advice is to avoid it in general.
I'm using OrientDB Community Edition 2.1.16.
This is the graph of my data:
I'm trying to retrieve all paths for given node using:
select $path from (traverse out('E1') from #13:5)
But what I get it's quite strange:
I would have expected that every path passing through second level nodes (#13:1,#13:2,#13:3) would have reached the root node (#13:0).
Something like:
(#13:5).out[0](#13:4).out[0](#13:1).out[0](#13:0)
(#13:5).out[0](#13:4).out[1](#13:2).out[0](#13:0)
(#13:5).out[0](#13:4).out[2](#13:3).out[0](#13:0)
It's that correct or what?
If yes, is there the possibility to get this result?
I mean to have a complete path from #13:5 to #13:0 passing through the second levels' nodes.
Thanks
The result you get depends on the strategy has the traverse, you can set two types: DEPTH_FIRST, the default, and BREADTH_FIRST. I think maybe you interests of the two strategies. For more info you can look at this link.
DEPTH_FIRST strategy
This is the default strategy used by OrientDB for traversal. It explores as far as possible along each branch before backtracking. It's implemented using recursion. To know more look at Depth-First algorithm. Below the ordered steps executed while traversing the graph using DEPTH_FIRST strategy:
Depth-first-tree
BREADTH_FIRST strategy
It inspects all the neighboring nodes, then for each of those neighbor nodes in turn, it inspects their neighbor nodes which were unvisited, and so on. Compare BREADTH_FIRST with the equivalent, but more memory-efficient iterative deepening DEPTH_FIRST search and contrast with DEPTH_FIRST search. To know more look at Breadth-First algorithm. Below the ordered steps executed while traversing the graph using BREADTH_FIRST strategy:
Breadth-first-tree
using your query
select $path from (traverse out('E1') from #13:5)
you get the path relative to every result of the traverse, you can verify that by adding the *
select *,$path from (traverse out('E') from #9:5)
In this way you get all the vertexes traversed and the path to get there from starting node.
I want to query the Overpass Api to find out the distance of special relations (railways). The request is fine, and returns me all relation, way and node objects I'm interested in. Example for Hamburg:
[out:json];(rel(53.55224324163863, 10.006766589408304, 53.55314275836137, 10.008081410591696)["route"="train"];>;);out body;
In Overpass, each relation object has members defining this relation. For way objects you can resolve the lat/lon of its node attributes and calculate the distance for that way. If you sum up all the way distances it seems to be reasonable.
However, there are members from that relation of the type node (most of the time, they have a role of "stop") which seem to represent the right order of stops from that relation. But instead being in between the members, they are roughly at the end.
If I try to look the stops up inside the ways, they are not all present. How am I supposed to calculate the distance between two particular stops?
There seems to be a misconception about relations. Relation members don't necessarily have to be sorted. Consequently you might have to sort the members yourself, if necessary at all.
You can take a look at JOSM which has a neat sorting algorithm for various types of relations. But I don't think it is able to place members with the role stop at the correct position. This isn't always possible because a way doesn't necessarily have to be split at each node with the stop role. This also means a single way can contain more than one node with a stop role, making it impossible to sort the relation members correctly. Unless you do some pre-processing for splitting each way accordingly.
For calculating the distance between each stop it seems unnecessary to sort the elements. Just follow the way by iterating over all each nodes and check for each node if it has a stop role in the corresponding relation. When reaching the end of the way continue with the one which shares the same node at its start or end and which is also member of the relation.