如何填充零到我的多维数组在javascript

Question

我正在学习javascript。我对操作多维数组很困惑。

var myarr = [ 
       [ 7, 9, 10 ], 
       [ 6, 9 ], 
       [ 5, 9 ] 
  ]

我想这样插入0。在javascript

中做这个的聪明方法是什么?

       [ 
           [ 7, 9, 10 ], 
           [ 6, 9, 0 ], 
           [ 5, 9, 0 ] 
       ]

Answer 1

你可以先得到内部数组的最大长度，然后压入0，直到所有内部数组的长度相同。

var myarr = [[7, 9, 10], [6, 9], [5, 9]],
    length = myarr.reduce(function (r, a) { return Math.max(r, a.length); }, 0);
myarr.forEach(function (a) {
    while (a.length < length) {
        a.push(0);
    };
});
console.log(myarr);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

var myarr = [ 
       [ 7, 9, 10 ], 
       [ 6, 9 ], 
       [ 5, 9 ] 
  ]
for(var i = 0; i < myarr.length; i++) {    
    if(myarr[i].length < myarr.length){
       myarr[i].push(0);
    }
}
console.log(myarr);

Answer 3

这是一个解决方案。

var myarr = [
  [7, 9, 10],
  [6, 9],
  [5, 9]
];
var rows = myarr.length;
var cols = 0;
for (var i in myarr) {
  if (myarr[i].length > cols)
    cols = myarr[i].length;
}
for (i = 0; i < rows; i++) {
  for (j = 0; j < cols; j++) {
    if (myarr[i][j] == undefined)
      myarr[i][j] = 0;
  }
}
console.log(myarr);

Answer 4

最好的方法是首先计算出最长的子数组长度，然后将子数组填充到相同的长度。

下面包括一个计算最长长度的函数和一个执行填充的函数:

function getMax(arr) {
  var max = 0;
  for (var i = 0; i < arr.length; i++) {
    if (arr[i].length > max)
      max = arr[i].length;
  }
  return max;
}
function pad(arr, max) {
  for (var i = 0; i < arr.length; i++) {
    for (var j = arr[i].length; j < max; j++)
      arr[i].push(0);
  }
}
var myarr = [
  [7, 9, 10],
  [6, 9],
  [5, 9]
];
pad(myarr, getMax(myarr));
console.log(myarr);

Answer 5

似乎你需要一个2维数组的方阵，所以试试这个:

var myarr = [
  [7, 9, 10],
  [6, 9],
  [5, 9, 1, 2, 3, 4, 5, 6, 7] // <--- for example purpose
];
var rows = myarr.length;
var cols = 0;
for(var i = 0; i < myarr.length; i++){
  if(myarr[i].length > cols)
    cols = myarr[i].length;
}
var limit = rows > cols ? rows : cols;
for(var i = 0; i < limit; i++){
  if(myarr[i] == undefined)
    myarr[i] = new Array(limit);
  for(var j = 0; j < limit; j++){
    if(typeof myarr[i][j] == "undefined")
      myarr[i][j] = 0;
  }
}
for(var i = 0; i < limit; i++){
  console.log(JSON.stringify(myarr[i]));
}

Answer 6

var maxLength=0;
for(var i=0;i<myarr.length;i++){
   if(myarr[i].length>maxLength){
      maxLength=myarr[i].length
  }
}
for(var i=0;i<myarr.length;i++){
    if(myarr[i].length!=maxLength){
    fillZeros(myarr[i])
    }
  }
function fillZeros(child){
    while(child.length!=maxLength)
     {child.push(0);}
}

Answer 7

如果你的数组是一个只有数字的任意嵌套填充数组，你可以使用递归函数，像我这样:

function fillArray(array,  val){
  for(var i=0; i<array.length; i++){    
    if(typeof(array[i]) === 'number'){
        array[i] = val;
    }else{
        fillArray(array[i],  val);
    }
  } 
}
var test = [5,[3,8,-1,[3,4,5,2,1],[2] ],[[2,2],[3]],[[2,3],[4]],[[2,4],[5]]];
fillArray(test, 0);

Answer 8

using map function

var arr = [ 
           [ 7, 9, 10 ], 
           [ 6, 9], 
           [ 5, 9] 
       ]
       var arr1 = arr.map(function(e){
       var arr2 = [];
        if(e.length < 3)
            e.push(0);
         arr2.push(e);
         return arr2;
       });
      alert(arr1);