That does solve the duplicate information problem but it makes updates
to node attributes (like weight) difficult. Let's say, I want to
assign the weight of each node to the average of its neighbors.
for(UndirectedGraphNode node : UndirectedGraph.getNodesList() ) {
double sum = 0;
int count = 0;
for(UndirectedGraphNodeReference neighbor :
node.getNeighborsList() ) {
sum += ????
count++;
}
node.setWeight(sum/count);
}
----- graph.proto -----
package graph;
option java_package = "graph";
option java_outer_classname = "UndirectedGraphType";
option optimize_for = CODE_SIZE;
message UndirectedGraphNodeReference {
required string id = 1;
required double weight = 2;
}
message UndirectedGraphNode {
required string id = 1;
repeated UndirectedGraphNodeReference neighbors = 2;
}
message UndirectedGraph {
repeated UndirectedGraphNode nodes = 1;
}
On Oct 22, 2:14 pm, Jeremy Leader <[EMAIL PROTECTED]> wrote:
> I was assuming all the properties of a node (weight, label, color,
> whatever) would be in UndirectedGraphNode; UndirectedGraphNodeReference
> would only have the id and nothing else.
>
> --
> Jeremy Leader
> [EMAIL PROTECTED]
>
> GDR wrote:
> > Thanks Jeremy. That worked!
> > But we now have information about the same node being replicated. For
> > instance, let's say we have a field 'weight' attached to each node as
> > shown below. This setup will replicate the weight information of a
> > node as many times as its degree. If the weight of a node changes, I
> > will have update all it's occurrences in the PB. Any way I can avoid
> > it?
>
> > package graph;
>
> > option java_package = "graph";
> > option java_outer_classname = "UndirectedGraphType";
> > option optimize_for = CODE_SIZE;
>
> > message UndirectedGraphNodeReference {
> > required string id = 1;
> > required double weight = 2;
> > }
>
> > message UndirectedGraphNode {
> > required string id = 1;
> > repeated UndirectedGraphNodeReference neighbors = 2;
> > }
>
> > message UndirectedGraph {
> > repeated UndirectedGraphNode nodes = 1;
> > }
>
> > On Oct 21, 6:37 pm, Jeremy Leader <[EMAIL PROTECTED]> wrote:
> >> Keep in mind that protobufs describe serialized data, and there's no
> >> concept of an object reference like Java uses. In your example, if A
> >> and B are neighbors, then in your proto, the data representing A
> >> contains the data representing B, and the data representing B contains
> >> the data representing A!
>
> >> One way around this is to implement your own form of references, perhaps
> >> using the node ids like this:
>
> >> package graph;
>
> >> option java_package = "graph";
> >> option java_outer_classname = "UndirectedGraph";
> >> option optimize_for = CODE_SIZE;
>
> >> message UndirectedGraphNodeReference {
> >> required string id = 0;
>
> >> }
>
> >> message UndirectedGraphNode {
> >> required string id = 0;
> >> repeated UndirectedGraphNodeReference neighbors;
>
> >> }
>
> >> message UndirectedGraph {
> >> repeated UndirectedGraphNode nodes;
>
> >> }
>
> >> --
> >> Jeremy Leader
> >> [EMAIL PROTECTED]
>
> >> GDR wrote:
> >>> Hi,
> >>> I'm wondering how would one go about implementing self-referential
> >>> data structures? As an exercise, I tried to implement a PB version of
> >>> the adjacency list representation of a graph. I'm having a hard time
> >>> getting it work. Any suggestions?
> >>> Thanks!
> >>> --- graph.proto ---
> >>> package graph;
> >>> option java_package = "graph";
> >>> option java_outer_classname = "UndirectedGraph";
> >>> option optimize_for = CODE_SIZE;
> >>> message UndirectedGraphNode {
> >>> required string id = 0;
> >>> repeated UndirectedGraphNode neighbors;
> >>> }
> >>> message UndirectedGraph {
> >>> repeated UndirectedGraphNode nodes;
> >>> }
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