From array of paths to object using reduce and recursion

Question

I need to convert an array of paths:

const paths = [
  "test1",
  "test1.test1children"
]

to an object with the following structure:

{
  name: "test1",
  id: "test1",
  children: [...test1 children],
}

I try with a reducer and a recursive function per array item, it is works but is pretty slow. Any suggestions to improve this code are welcome. Thanks in advance.

  const iterRow = (row, obj) => {
    if (Array.isArray(row) && row.length !== 0) {
      const [name, ...pathStack] = row;
      const found = (n) => obj.children.find((i) => i.name === n);

      if (obj.name === name) {
        iterRow(pathStack, obj);
      } else {
        const newLeaf = {
          name,
          id: `${obj.id}.${name}`,
          children: [],
        };
        if (!found(name)) {
          obj.children.push(newLeaf);
        }
        iterRow(pathStack, found(name));
      }
    }
  };
  
const argOptionsProcessed = (rows) => rows.reduce((acc, row) => {
    const path = row.split('.');
    const found = () => acc.find((item) => path[0] === item.name);
    if (!found()) {
      acc.push({ name: path[0], id: path[0], children: [] });
    }
    iterRow(path, found());
    return acc;
  }, []);
  
  
  
const paths = [
"test1",
"test1.test1children",
"test1.test1children.test1subchildren",
"test1.test1children.test1subchildren.test1subsubchildren",
"tets2",
"test2.test2children",
]


console.log(argOptionsProcessed(paths));

This question may be better suited for codereview.stackexchange.com — kai
– kai, Commented Jun 25, 2020 at 8:05
Btw i am not sure if your code is working. I get back 3 instead of 2 objects. The object with id test2 is contained twice. — kai
– kai, Commented Jun 25, 2020 at 8:08
And better provide an abstract explanation of the algorithm you used, so people can help you improving this algorithm and have not to understand your whole code. — kai
– kai, Commented Jun 25, 2020 at 8:10

Nenad Vracar · Accepted Answer · 2020-06-25 08:16:52Z

3

You could do this without recursion using forEach and reduce methods and one object to keep nested levels.

const paths = [
  "test1",
  "test1.test1children",
  "test1.test1children.test1subchildren",
  "test1.test1children.test1subchildren.test1subsubchildren",
  "test2",
  "test2.test2children",
]

const result = []
const levels = { result }

paths.forEach(path => {
  let id = '';

  path.split('.').reduce((r, name, i, a) => {
    id += (id ? '.' : '') + name;

    if (!r[name]) {
      r[name] = { result: [] }
      r.result.push({ name, id, children: r[name].result })
    }

    return r[name]
  }, levels)
})

console.log(result)

answered Jun 25, 2020 at 8:16

Nenad Vracar

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1 Comment

David Over a year ago

You are right! thank you very much! ill try in my own code thanks again

Nina Scholz · Accepted Answer · 2020-06-25 08:40:46Z

0

You could take a shorter approach by reducing the array and the path and search for same name.

const
    getTree = data => data.reduce((tree, path) => {
        path.split('.').reduce((t, name, i, a) => {
            let temp = t.find(q => q.name === name);
            if (!temp) t.push(temp = { name, id: a.slice(0, i + 1).join('.'), children: [] });
            return temp.children;
        }, tree);
        return tree;
    }, []),
    paths = ["test1", "test1.test1children", "test1.test1children.test1subchildren", "test1.test1children.test1subchildren.test1subsubchildren", "tets2", "test2.test2children"]

console.log(getTree(paths));

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answered Jun 25, 2020 at 8:40

Nina Scholz

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Comments

KooiInc · Accepted Answer · 2020-06-25 08:58:42Z

Here's another solution.

const paths = [
  "test1",
  "test1.test1children",
  "test1.test1children.test1subchildren",
  "test1.test1children.test1subchildren.test1subsubchildren",
  "test2",
  "test2.test2children",
];

console.log(untangle(paths));

function untangle(paths) {
  return paths.reduce( (a, v) => {
    const path = v.split(".");
    if (path.length < 2) {
      const l0 = path[0];
      let level0 = {name: l0, id: l0, children: []};
      let tryChildren = paths
        .filter( p => ~p.indexOf(".") && p.startsWith(l0) )
      if (tryChildren.length) {
        tryChildren = tryChildren.map( p => p.substr( p.indexOf(".")+1 ) );
        level0.children = level0.children.concat(untangle(tryChildren));
      }
      a.push(level0);
    }
    return a;
  }, []);
}

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