如何获取 JavaScript 中两个数组之间的差异，包括移动的项目

Question

我有两个数组，代表同一个数组的两个版本，我想知道它们之间的区别。

与earlier questions不同，我还想了解仅移动的项目。如果一个项目在两个数组中，但它在不同的地方，我想知道它。此外，我不希望结果差异中的项目只是因为添加或删除了其他项目而移动，这当然会导致所有后续项目更改索引。我只认为项目已经移动，如果它们改变了彼此的相对位置。

let old = [ "b", "c", "d", "e", "f", "g", "h", "i", "j" ];
let news = [ "a", "d", "c", "e", "f", "h", "i", "j" ];

// algo should result in
let added = [ "a" ];
let removed = [ "b", "g" ];
let moved = [ "d", "c" ];

Answer 1

let old = [ "b", "c", "d", "e", "f", "g", "h", "i", "j" ];
let news = [ "a", "d", "c", "e", "f", "h", "i", "j" ];

let added = news.filter(item => !old.includes(item));
let removed = old.filter(item => !news.includes(item));
// find items that only changed place
let oldCommon = old.filter(item => news.includes(item));
let newCommon = news.filter(item => old.includes(item));
let moved = newCommon.filter((item, i) => item != oldCommon[i]);

console.log("added", added);
console.log("removed", removed);
console.log("moved", moved);

Answer 2

此解决方案还处理重复问题。

let oldArray = [ "b", "c", "d", "e", "f", "g", "h", "i", "j" ];
let newArray = [ "a", "d", "c", "e", "f", "h", "i", "j" ];

let added = newArray.filter(function(item) {
  return oldArray.indexOf(item) === -1;
});
let removed = oldArray.filter(function(item) {
  return newArray.indexOf(item) === -1;
});
let moved = newArray.filter(function(item) {
  return oldArray.indexOf(item) !== -1 &&
    newArray.indexOf(item) !== -1 &&
    oldArray.indexOf(item) !== newArray.indexOf(item);
});
console.log(added);
console.log(removed);
console.log(moved);

Answer 3

添加和删除的元素应该清楚。对于移动的元素，我们必须根据添加和删除的元素跟踪索引。

我遍历 newArray，如果我找到一个添加的元素，我将它的索引标记为 -1，然后我将在我离开的地方继续索引，即：[0, 1, -1, 2, 3]

在删除元素的情况下，如果我找到删除的索引，那么我将增加当前索引和以下所有索引，即：如果删除的索引为 5，则 [0,1,2,3,4 ,5,6,7,8] 变为 [0,1,2,3,4,6,7,8,9]。

最后我只是遍历 newWithIndexes 并将索引（我计算的）与 oldArrays 索引进行比较。

let oldArray = [ "b", "c", "d", "e", "f", "g", "h", "i", "j" ];
let newArray = [ "a", "d", "c", "e", "f", "h", "i", "j" ];

let added = newArray.filter(item => oldArray.indexOf(item) == -1);
let removed = oldArray.filter(item => newArray.indexOf(item) == -1);

var removedIndexes = [];
for (let removedItem of removed) {
  removedIndexes.push(oldArray.indexOf(removedItem));
}

let newWithIndexes = [];
var addedCount = 0;
let i = 0;
for (let item of newArray) {
  if (added.includes(item)) {
    newWithIndexes.push({el: item, index: -1});
    addedCount++;
  } else {
    newWithIndexes.push({el: item, index: i - addedCount});
  }
  i++;
}

var removedCount = 0;
for (let newWithIndex of newWithIndexes) {
  if (removedIndexes.includes(newWithIndex.index + removedCount)) {
    removedCount++;
  }

  if (newWithIndex.index != -1) {
    newWithIndex.index += removedCount;
  }
}

let moved = [];
for (let newWithIndex of newWithIndexes) {
  if (newWithIndex.index != oldArray.indexOf(newWithIndex.el)) {
    moved.push(newWithIndex.el);
  }
}

console.log(added);
console.log(removed);
console.log(moved);

如何获取 JavaScript 中两个数组之间的差异，包括移动的项目

How to get the differences between two arrays in JavaScript, including moved items

javascript

arrays

algorithm

diff

difference