UsageGraphError: Graph.addNode: the "Jessica" node already exist in the graph.

[mooijtech]

Hello again,

I'm having trouble getting ForceAtlas2 to work.

The following code works:

import React from "react";
import {useSigma} from "react-sigma-v2";
import {random} from "graphology-layout"

export const NetworkGraph = ({nodes, links}) => {
    const sigma = useSigma();
    const graph = sigma.getGraph();

    graph.addNode("Jessica", { label: "Jessica", x: 0, y: 1, color: "#FF0", size: 10 });
    graph.addNode("Truman", { label: "Truman", x: 1, y: 0, color: "#00F", size: 10 });
    graph.addEdge("Jessica", "Truman", { color: "#CCC", size: 1 });

    random.assign(graph);

    return null;
}

But calling https://graphology.github.io/standard-library/layout-forceatlas2.html after the random assign doesn't:

forceAtlas2.assign(graph);

UsageGraphError: Graph.addNode: the "Jessica" node already exist in the graph.

Do you know what could be the issue?

[mooijtech]

It seems to work when I do a check for if the graph has the node:

  if (!graph.hasNode("Jessica")) {
        graph.addNode("Jessica", { label: "Jessica", x: 0, y: 1, color: "#FF0", size: 10 });
    }

Not sure why it's not removing the nodes on unmount.

[sim51]

The graph stays the same, event on unmount, it is stored on the SigmaContainer component.

FYI, graphology has some merge functions to add or update nodes/edges.

BTW, I don't know why your component should be remounted, ... generally the properties of the SigmaContainer are pretty much immutable, so the tree should not be re-rendered ...

What are the nodes & links props ?

[mooijtech]

Thanks for the explanation, I appreciate your feedback as always.
I didn't know the state was persisted, I have added a useEffect when adding nodes and this works.

Thanks for this library.

EDIT: The nodes and links props are my actual data but I was using your example as a demo, I will update the code to add nodes from these props.