使用Javascript / Typescript从1D数组创建3D数组

Question

I would like to create 3D array of 1D I have

  let a = ['hello', 'my', 'friend']

And I tried to create 3D array like this

b = [[['h'], ['e'], ['l'], ['l'], ['o']], [['m'], ['y']], [['f'], ['r'], ['i'] ,['e'], ['n'], ['d']]]

but nothing works..

How could I do something like this?

Answer 1

This uses the spread operator to implicitly invoke String#[@@iterator]() for each word and then map() s each character to a unit-length array:

 let a = ['hello', 'my', 'friend']; let b = a.map(word => [...word].map(c => [c])); console.log(JSON.stringify(b)); 

If you are attempting to run this using Typescript as a preprocessor, you'll need to call the generically implemented Array#slice() on each word instead, since they are Array-like objects (and for some reason Typescript doesn't recognize that):

 let slice = Function.call.bind(Array.prototype.slice); let a = ['hello', 'my', 'friend']; let b = a.map(word => slice(word).map(c => [c])); console.log(JSON.stringify(b)); 

Answer 2

Using map twice works just fine.

let a = ['hello', 'my', 'friend'];

let result = a.map((word) => word.split('')
.map((letter) => [letter]))

console.log(result)

Answer 3

here is a more rudimentary option

function convertStringIntoArray(str){
    var arr = [];
    var words = str.split(" ");
    for(var j=0; j<words.length; j++){
        var word = words[j];
        var innerArr = [];
        for(var i=0; i<word.length; i++){
            innerArr.push([word.charAt(i)]);
        }
        arr.push(innerArr);
    }
    return arr;
} 

Answer 4

The map command returns an array - so by calling it once you will get an array characters.

a.map(function(item) { return [ item.split('') ]; })
// [[["h","e","l","l","o"]],[["m","y"]],[["f","r","i","e","n","d"]]]

If you call map a second time for each character, you can wrap each item in an array.

let b = a.map(function(item) { 
    return item.split('').map(function(inner) { 
                                    return [ inner ]; 
                                }); 
})
// [[["h"],["e"],["l"],["l"],["o"]]],[[["m"],["y"]]],[[["f"],["r"],["i"],["e"],["n"],["d"]]]