将数组拆分为大块

JavaScript

逆天卡卡西

2020-03-12

假设我有一个如下所示的Javascript数组:

["Element 1","Element 2","Element 3",...]; // with close to a hundred elements.

什么方法适合将数组分块(拆分)为更小的数组,最多可以有10个元素?

第1293篇《将数组拆分为大块》来自Winter(https://github.com/aiyld/aiyld.github.io)的站点

24个回答
飞云斯丁GO 2020.03.12

Here is neat & optimised implemention of chunk() function. Assuming default chunk size is 10.

var chunk = function(list, chunkSize) {
  if (!list.length) {
    return [];
  }
  if (typeof chunkSize === undefined) {
    chunkSize = 10;
  }

  var i, j, t, chunks = [];
  for (i = 0, j = list.length; i < j; i += chunkSize) {
    t = list.slice(i, i + chunkSize);
    chunks.push(t);
  }

  return chunks;
};

//calling function
var list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
var chunks = chunk(list);
Pro番长 2020.03.12

EDIT: @mblase75 added more concise code to the earlier answer while I was writing mine, so I recommend going with his solution.

You could use code like this:

var longArray = ["Element 1","Element 2","Element 3", /*...*/];
var smallerArrays = []; // will contain the sub-arrays of 10 elements each
var arraySize = 10;
for (var i=0;i<Math.ceil(longArray.length/arraySize);i++) {
    smallerArrays.push(longArray.slice(i*arraySize,i*arraySize+arraySize));
}

Change the value of arraySize to change the maximum length of the smaller arrays.

卡卡西Harry 2020.03.12

Here is a non-mutating solution using only recursion and slice().

const splitToChunks = (arr, chunkSize, acc = []) => (
    arr.length > chunkSize ?
        splitToChunks(
            arr.slice(chunkSize),
            chunkSize,
            [...acc, arr.slice(0, chunkSize)]
        ) :
        [...acc, arr]
);

Then simply use it like splitToChunks([1, 2, 3, 4, 5], 3) to get [[1, 2, 3], [4, 5]].

Here is a fiddle for you to try out: https://jsfiddle.net/6wtrbx6k/2/

斯丁米亚Green 2020.03.12

Use chunk from lodash

lodash.chunk(arr,<size>).forEach(chunk=>{
  console.log(chunk);
})
ProGreen 2020.03.12

ES6 spreads functional #ohmy #ftw

const chunk =
  (size, xs) => 
    xs.reduce(
      (segments, _, index) =>
        index % size === 0 
          ? [...segments, xs.slice(index, index + size)] 
          : segments, 
      []
    );

console.log( chunk(3, [1, 2, 3, 4, 5, 6, 7, 8]) );

阿飞Harry小胖 2020.03.12

This is the most efficient and straight-forward solution I could think of:

function chunk(array, chunkSize) {
    let chunkCount = Math.ceil(array.length / chunkSize);
    let chunks = new Array(chunkCount);
    for(let i = 0, j = 0, k = chunkSize; i < chunkCount; ++i) {
        chunks[i] = array.slice(j, k);
        j = k;
        k += chunkSize;
    }
    return chunks;
}
Jim老丝L 2020.03.12

ES6 one-line approach based on Array.prototype reduce and push methods:

const doChunk = (list, size) => list.reduce((r, v) =>
  (!r.length || r[r.length - 1].length === size ?
    r.push([v]) : r[r.length - 1].push(v)) && r
, []);

console.log(doChunk([0,1,2,3,4,5,6,7,8,9,10,11,12], 5));
// [[0, 1, 2, 3, 4], [5, 6, 7, 8, 9], [10, 11, 12]]
达蒙西里 2020.03.12

以下ES2015方法无需定义函数即可直接在匿名数组上工作(例如,块大小为2):

[11,22,33,44,55].map((_, i, all) => all.slice(2*i, 2*i+2)).filter(x=>x.length)

如果要为此定义一个函数,可以按以下步骤进行操作(改进K._Blazemonger的回答的评论):

const array_chunks = (array, chunk_size) => array
    .map((_, i, all) => all.slice(i*chunk_size, (i+1)*chunk_size))
    .filter(x => x.length)
Sam神奇A 2020.03.12

ES6 Generator version

function* chunkArray(array,size=1){
    var clone = array.slice(0);
    while (clone.length>0) 
      yield clone.splice(0,size); 
};
var a = new Array(100).fill().map((x,index)=>index);
for(const c of chunkArray(a,10)) 
    console.log(c);
宝儿猴子 2020.03.12
results = []
chunk_size = 10
while(array.length > 0){
   results.push(array.splice(0, chunk_size))
}
Me无敌小哥 2020.03.12
in coffeescript:

b = (a.splice(0, len) while a.length)

demo 
a = [1, 2, 3, 4, 5, 6, 7]

b = (a.splice(0, 2) while a.length)
[ [ 1, 2 ],
  [ 3, 4 ],
  [ 5, 6 ],
  [ 7 ] ]
斯丁理查德 2020.03.12

为此https://www.npmjs.com/package/array.chunk创建了一个npm包

var result = [];

for (var i = 0; i < arr.length; i += size) {
  result.push(arr.slice(i, size + i));
}
return result;

使用TypedArray时

var result = [];

for (var i = 0; i < arr.length; i += size) {
  result.push(arr.subarray(i, size + i));
}
return result;
小小Stafan宝儿 2020.03.12

我认为这是使用ES6语法的不错的递归解决方案:

const chunk = function(array, size) {
  if (!array.length) {
    return [];
  }
  const head = array.slice(0, size);
  const tail = array.slice(size);

  return [head, ...chunk(tail, size)];
};

console.log(chunk([1,2,3], 2));

JinJin凯梅 2020.03.12

使用发电机

function* chunks(arr, n) {
 for(let i = 0; i < arr.length; i += n) {
     yield(arr.slice(i, i+n));
     }
}
let someArray = [0,1,2,3,4,5,6,7,8,9]
console.log([...chunks(someArray, 2)]) // [[0,1],[2,3],[4,5],[6,7],[8,9]]

Sam飞云 2020.03.12

我的目标是在纯ES6中创建一个简单的非变异解决方案。javascript中的特殊性使得有必要在映射前填充空数组:-(

function chunk(a, l) { 
    return new Array(Math.ceil(a.length / l)).fill(0)
        .map((_, n) => a.slice(n*l, n*l + l)); 
}

这个带有递归的版本看起来更简单,更引人注目:

function chunk(a, l) { 
    if (a.length == 0) return []; 
    else return [a.slice(0, l)].concat(chunk(a.slice(l), l)); 
}

ES6的荒谬的数组功能令人困惑:-)

ProGO 2020.03.12

有很多答案,但这是我使用的:

const chunk = (arr, size) =>
  arr
    .reduce((acc, _, i) =>
      (i % size)
        ? acc
        : [...acc, arr.slice(i, i + size)]
    , [])

// USAGE
const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
chunk(numbers, 3)

// [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]]

首先,检查索引除以块大小时是否有余数。

如果还有余数,则只返回累加器数组。

如果没有余数,则索引可以被块大小整除,因此从原始数组中获取一个切片(从当前索引开始),然后将其添加到累加器数组中。

因此,针对reduce的每次迭代返回的累加器数组如下所示:

// 0: [[1, 2, 3]]
// 1: [[1, 2, 3]]
// 2: [[1, 2, 3]]
// 3: [[1, 2, 3], [4, 5, 6]]
// 4: [[1, 2, 3], [4, 5, 6]]
// 5: [[1, 2, 3], [4, 5, 6]]
// 6: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
// 7: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
// 8: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
// 9: [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]]
乐米亚 2020.03.12

好吧,让我们从一个相当紧的开始:

function chunk(arr, n) {
    return arr.slice(0,(arr.length+n-1)/n|0).
           map(function(c,i) { return arr.slice(n*i,n*i+n); });
}

像这样使用:

chunk([1,2,3,4,5,6,7], 2);

然后我们有这个紧密的reducer函数:

function chunker(p, c, i) {
    (p[i/this|0] = p[i/this|0] || []).push(c);
    return p;
}

像这样使用:

[1,2,3,4,5,6,7].reduce(chunker.bind(3),[]);

由于小猫绑定this到数字时会死亡,因此我们可以像这样手动手动计算:

// Fluent alternative API without prototype hacks.
function chunker(n) {
   return function(p, c, i) {
       (p[i/n|0] = p[i/n|0] || []).push(c);
       return p;
   };
}

像这样使用:

[1,2,3,4,5,6,7].reduce(chunker(3),[]);

然后,仍然非常紧凑的功能可以一次性完成所有工作:

function chunk(arr, n) {
    return arr.reduce(function(p, cur, i) {
        (p[i/n|0] = p[i/n|0] || []).push(cur);
        return p;
    },[]);
}

chunk([1,2,3,4,5,6,7], 3);
古一老丝宝儿 2020.03.12

如今,您可以使用lodash的块函数将数组拆分为更小的数组https://lodash.com/docs#chunk不再需要弄乱循环了!

小宇宙路易 2020.03.12

ECMA 6中的一线

const [list,chuckSize] = [[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], 6]

new Array(Math.ceil(list.length / chuckSize)).fill().map(_ => list.splice(0,chuckSize))
ASamJim 2020.03.12

我更喜欢使用拼接方法:

var chunks = function(array, size) {
  var results = [];
  while (array.length) {
    results.push(array.splice(0, size));
  }
  return results;
};
TomProSam 2020.03.12

旧问题:新答案!实际上,我正在研究此问题的答案,并且有一位朋友对此进行了改进!所以这里是:

Array.prototype.chunk = function ( n ) {
    if ( !this.length ) {
        return [];
    }
    return [ this.slice( 0, n ) ].concat( this.slice(n).chunk(n) );
};

[1,2,3,4,5,6,7,8,9,0].chunk(3);
> [[1,2,3],[4,5,6],[7,8,9],[0]]
阳光樱前端 2020.03.12

我在jsperf.com中测试了不同的答案。结果在此处可用:https : //web.archive.org/web/20150909134228/https : //jsperf.com/chunk-mtds

最快的功能(可从IE8使用)是这一功能:

function chunk(arr, chunkSize) {
  var R = [];
  for (var i=0,len=arr.length; i<len; i+=chunkSize)
    R.push(arr.slice(i,i+chunkSize));
  return R;
}
理查德Stafan 2020.03.12

如果您不知道谁在使用您的代码(第三方,同事,您自己等),请尝试避免与原生原型(包括Array.prototype)混为一谈。

有一些方法可以安全地扩展原型(但不是在所有浏览器中),并且可以安全地使用从扩展的原型创建的对象,但是更好的经验法则是遵循“最不惊奇原则”并完全避免这些做法。

如果您有时间,请观看Andrew Dupont在JSConf 2011上的演讲“一切都允许:扩展内置插件”,以获取有关此主题的精彩讨论。

但是回到问题所在,尽管上述解决方案可以工作,但它们过于复杂,需要不必要的计算开销。这是我的解决方案:

function chunk (arr, len) {

  var chunks = [],
      i = 0,
      n = arr.length;

  while (i < n) {
    chunks.push(arr.slice(i, i += len));
  }

  return chunks;
}

// Optionally, you can do the following to avoid cluttering the global namespace:
Array.chunk = chunk;
西里小哥 2020.03.12

array.slice方法可以从一开始,中间,或自己需要的任何目的数组的结束提取切片,在不改变原来的数组。

var i,j,temparray,chunk = 10;
for (i=0,j=array.length; i<j; i+=chunk) {
    temparray = array.slice(i,i+chunk);
    // do whatever
}

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