从平面数组创建树对象

Question

I am a little stuck on this. I want to create a tree structure from a flat array. Say I have this input:

var input = [
    ["a","b","c"],
    ["a", "b","d"],
    ["e","f","g"],
];

I want to create a tree structure looking like the following:

// output:
[
    {
        id: "a",
        children: [
            {id: "b", children: [
                {id: "c", children: []},
                {id: "d", children: []}
            ]},
        ] 
    },
    { 
        id: "e",
        children: [
          {
              id: "f",
              children: [{ id: "g", children: []}]
          },
        ]
    }
]

One way I was thinking of doing this was having a map of all of the parent and iterate through the input array to set the parent to child mappings. But I come to problems when trying to actually construct the tree object from that map and avoiding duplicates. Any pointers are appreciated, thanks!

Answer 1

I found the solution to a problem that is similar to your question.

_makeTree

If you have data that looks like this:

_makeTree({ q:
    [
        {"id": 123, "parentid": 0, "name": "Mammals"},
        {"id": 456, "parentid": 123, "name": "Dogs"},
        {"id": 214, "parentid": 456, "name": "Labradors"},
        {"id": 810, "parentid": 456, "name": "Pugs"},
        {"id": 919, "parentid": 456, "name": "Terriers"}
    ]
});

Parameters:

• q (Array): A query result (see example below)
• id (String): The name of the id column (Default: "id")
• parentid (String): The name of the ParentItemID column (Default: "parentid")
• children (String): The name of the "children" array to be created in rows that have children (Default: "children")

Then result should be something like the following structure:

[
    {
        "id": 123,
        "parentid": 0,
        "name": "Mammals",
        "children": [
            {
                "id": 456,
                "parentid": 123,
                "name": "Dogs",
                "children": [
                    {
                        "id": 214,
                        "parentid": 456,
                        "name": "Labradors"
                    },
                    {
                        "id": 810,
                        "parentid": 456,
                        "name": "Pugs"
                    },
                    {
                        "id": 919,
                        "parentid": 456,
                        "name": "Terriers"
                    }
                ]
            }
        ]
    }
]

Now, _makeTree codes:

 var _makeTree = function(options) { var children, e, id, o, pid, temp, _i, _len, _ref; id = options.id || "id"; pid = options.parentid || "parentid"; children = options.children || "children"; temp = {}; o = []; _ref = options.q; for (_i = 0, _len = _ref.length; _i < _len; _i++) { e = _ref[_i]; temp[e[id]] = e; if (temp[e[pid]] != null) { if (temp[e[pid]][children] == null) { temp[e[pid]][children] = []; } temp[e[pid]][children].push(e); } else { o.push(e); } } return o; }; 

References:

I need to create a custom tree data-structure using JavaScript

Creating trees from SQL queries in Javascript

_makeTree library