Recursively make a nested object given an array of objects and array of children?-CodePudding

I am trying to create a nested object recursively. Here is the sample data:

 "reactions": [
    {
      "name": "Ester amidation",
      "target": "Data #1",
      "sources": ["Data #2", "Data #3"],
    },
    {
      "name": "Buchwald-Hartwig amination with amide",
      "target": "Data #4",
      "sources": ["Data #5", "Data #1"], // BECAUSE Data #1 is a target AND in sources for Data #4, we should nest it as a child of Data #4
    }
  ]

Given the target, I was trying to have something that will output something like:

{
    name: "My Route 1",
    children: [
      {
        name: "Data #4",
        children: [
          {
            name: "Data #5",
            children: []
          },
          {
            name: "Data #1",
            children: [
                {
                    name: "Data #2",
                    children: []
                },
                {
                    name: "Data #3",
                    children: []
                }
                
            ]
          },
        ],
      },
    ],
  };

I have tried something like this but I get confused when it comes to handling arrays:

function createNestedTree(objects, target = null) {
    const children = objects.filter(o => o.target === target);
    if (!children.length) {
        return null;
    }
    return children.map(child => ({
        ...child,
        children: createNestedTree(objects, child.id)
    }));
}

Anyone have an idea of how to create an algorithm for this? Much appreciated!

CodePudding user response：

You could first iterate the data to create the target objects (with empty children arrays), and reference them in a Map keyed by name. Then iterate the data to populate those children arrays, and at the same time mark children as not being a root. Return the remaining root(s).

Here is a possible implementation:

function makeTree(reactions) {
    const map = new Map(reactions.flatMap(({target, sources}) => 
        [target, ...sources].map(name => [name, { name, children: [] }])
    ));
    const roots = new Map(map);
    for (const {target, sources} of reactions) {
        for (const source of sources) {
            map.get(target).children.push(map.get(source));
            roots.delete(source);
        }
    }
    return [...roots.values()];
}

const reactions = [{"name": "Ester amidation","target": "Data #1","sources": ["Data #2", "Data #3"],},{"name": "Buchwald-Hartwig amination with amide","target": "Data #4","sources": ["Data #5", "Data #1"]}];  
const result = makeTree(reactions);
console.log(result);