问对JavaScript中除一个元素以外的数组进行排序
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Stack Overflow用户

提问于 2018-07-27 19:39:41

回答 7查看 16.1K关注 0票数 38

我有一个数组，我正在对它进行排序，但我需要对数组中除一个元素以外的所有元素进行排序。

我的数组是：

var Comparison = [
    {key: "None", value: "None"},
    {key:"Geographical Area", value:"Geographical_Area"},
    {key:"Forests", value:"Forests"},
    {key:"Barren Unculturable Land", value:"Barren_Unculturable_Land"},
    {key:"Land put to Non agricultural use", value:"Land_put_to_Non_agricultural_use"},
    {key:"Land Area", value:"Land_Area"},
    {key:"Water Area", value:"Water_Area"},
    {key:"Culturable Waste", value:"Culturable_Waste"},
    {key:"Permanent Pastures", value:"Permanent_Pastures"},
    {key:"Land under Tree Crops", value:"Land_under_Tree_Crops"},
    {key:"Fallow Land excl Current Fallow", value:"Fallow_Land_excl_Current_Fallow"},
    {key:"Current Fallow", value:"Current_Fallow"},
    {key:"Total Unculturable Land", value:"Total_Unculturable_Land"},
    {key:"Net Sown Area", value:"Net_Sown_Area"},
    {key:"Gross Sown Area", value:"Gross_Sown_Area"},
    {key:"Cropping Intensity", value:"Cropping_Intensity"} ];

我使用下面的代码对这个数组进行排序：

var Comparison_sort = this.Comparison.sort(function (a, b) {
  if (a.key < b.key)
      return -1;
  if (a.key > b.key)
      return 1;
  return 0;
});

这对我的数组进行了完美的排序，但我希望我的一个元素在顶部，这意味着我的元素None应该在顶部，并对所有其他元素进行排序。

例如，我得到这样的结果：

   {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}
   {key: "Cropping Intensity", value: "Cropping_Intensity"}
   {key: "Culturable Waste", value: "Culturable_Waste"}
    ....
   {key: "None", value: "None"}

但我想要这样的结果：

   {key: "None", value: "None"}
   {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}
   {key: "Cropping Intensity", value: "Cropping_Intensity"}
   {key: "Culturable Waste", value: "Culturable_Waste"}
    ....

我看到了一个答案，，但我无法使用这个答案来解决我的问题。

javascript

arrays

sorting

回答 7

Stack Overflow用户

回答已采纳

发布于 2018-07-27 19:42:50

var Comparison_sort = this.Comparison.sort(function (a, b) {
  if(a.key == b.key) return 0;
  if (a.key == 'None') return -1;
  if (b.key == 'None') return 1;

  if (a.key < b.key)
      return -1;
  if (a.key > b.key)
      return 1;
  return 0;
});

告诉“进行常规排序，除非键是none，这意味着它必须首先排序。”

票数 41

Stack Overflow用户

发布于 2018-07-27 20:51:18

或者，您可以过滤掉none，并对其他元素进行排序。然后在最后将它们连接回彼此。

const comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

const result = comparison
               .filter(e => e.key === 'None')
               .concat(
                 comparison.filter(e => e.key !== 'None')
                           .sort((a, b) => a.key.localeCompare(b.key))
               );
               
console.log(result);

解释：

const comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

// fetch all elements with the key 'None'
const nones = comparison.filter(e => e.key === 'None');
// fetch all elements with the key not 'None'
const others = comparison.filter(e => e.key !== 'None')
// sort the elements in the array by key
                         .sort((a, b) => a.key.localeCompare(b.key));
// concatenate the 2 arrays together
const result = nones.concat(others);

console.log(result);

这要归功于Pac0s answer。在写完我的解决方案后，我发现我基本上做了他的解释的一个工作版本。我已经来不及在他的答案中添加我的例子了，因为这是目前两个答案中支持率最高的。

对于较大的数组，在同一数组上使用两次filter()并使用相反的谓词(检查回调)可能会有点低效。您可以选择引入像partition()这样的辅助函数来帮助减少必须完成的迭代量。

function partition(forEachable, callback) {
  const partitions = { "true": [], "false": [] };
  forEachable.forEach((...args) => partitions[!!callback(...args)].push(args[0]));
  return [partitions[true], partitions[false]];
}

let comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

const [nones, others] = partition(comparison, e => e.key === "None");
others.sort((a, b) => a.key.localeCompare(b.key));
const result = nones.concat(others);
console.log(result);

票数 10

Stack Overflow用户

发布于 2018-07-27 20:06:07

您可以使用reduce来实现所需的输出：

var Comparison = [{key:"Geographical Area", value:"Geographical_Area"},   {key:"Forests", value:"Forests"},   {key:"Barren Unculturable Land", value:"Barren_Unculturable_Land"}, {key: "None", value: "None"},  {key:"Land put to Non agricultural use", value:"Land_put_to_Non_agricultural_use"}, {key:"Land Area", value:"Land_Area"},   {key:"Water Area", value:"Water_Area"}, {key:"Culturable Waste", value:"Culturable_Waste"}, {key:"Permanent Pastures", value:"Permanent_Pastures"}, {key:"Land under Tree Crops", value:"Land_under_Tree_Crops"},   {key:"Fallow Land excl Current Fallow", value:"Fallow_Land_excl_Current_Fallow"},   {key:"Current Fallow", value:"Current_Fallow"}, {key:"Total Unculturable Land", value:"Total_Unculturable_Land"},   {key:"Net Sown Area", value:"Net_Sown_Area"},   {key:"Gross Sown Area", value:"Gross_Sown_Area"},   {key:"Cropping Intensity", value:"Cropping_Intensity"},]

var Comparison_sort = Comparison
                      .sort((a, b) => a.key.localeCompare(b.key))
                      .reduce((acc, e) => {
                        e.key === 'None' ? acc.unshift(e) : acc.push(e);
                        return acc;
                      }, []);

console.log(Comparison_sort);

使用reduce版本-2进行排序：

let comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

var {Comparison_sort} = comparison.reduce((acc, obj, idx, arr) => {
                                  obj.key === 'None' ? acc['first'].push(obj) : acc['last'].push(obj)
                                  if (idx === arr.length - 1) (acc['last'].sort((a, b) => a.key.localeCompare(b.key)), acc['Comparison_sort'] = [...acc['first'], ...acc['last']])
                                  return acc
                                }, {first: [], last: [], Comparison_sort: []})

console.log(Comparison_sort);

票数 4

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/51557177

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