如何按属性值的长度过滤重复项答案

【问题标题】：how to filter duplicates by the length of a property value如何按属性值的长度过滤重复项
【发布时间】：2020-04-16 20:52:25
【问题描述】：

我有一个重复的对象数组。它应该有重复，但它需要限制在其中一个属性值中的月数。

const DATA = [
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "WAYZETTA 67-2536H",
    "entityId": 31135395,
    "selectedColumn": "Mar",
    "selectedColumns": "Mar"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  }
]

const DESIRED_RESULT = [
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Jan",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "MARYS DRAW 461-2227H",
    "entityId": 31340479,
    "selectedColumn": "Feb",
    "selectedColumns": "Jan Feb"
  },
  {
    "wellName": "WAYZETTA 67-2536H",
    "entityId": 31135395,
    "selectedColumn": "Mar",
    "selectedColumns": "Mar"
  }
]

我已经给出了期望的结果。每个 wellName（例如 MARYS DRAW 461-2227H）都会有一个属性 selectedColumns 和一串月份。我需要将重复项限制为相同的月数，并且每个重复项都需要将 3 个月中的一个设置为 selectedColumn。

【问题讨论】：

什么具体表示重复，当遇到重复时会发生什么？拿第一个？最后一个？有关系吗？
根本不重要
您自己尝试过吗？结果如何？我们可以看到代码吗？
所以您要确保输出数组中没有两个对象具有相同的selectedColumn 和selectedColumns 值？
^^^ 还是只检查 entityId 就足够了？您需要具体检查哪些“重复”是否属实

标签： javascript jquery lodash

【解决方案1】：

这可能是您正在寻找的：

let result = [];
let filter = {};
let col, cols;

// Iterate through every element
data.forEach(datum => {
  col = datum.selectedColumn;
  cols = datum.selectedColumns;
  // Add selectedColumns value if not already tracked
  if (!filter[cols]) {
    filter[cols] = [];
  }
  // Make sure element with same selectedColumn value doesn't already exist
  if (filter[cols].indexOf(col) === -1) {
    filter[cols].push(col);
    result.push(datum);
  }
})

基本上，它所做的是跟踪找到的 selectedColumns 值，然后将每个值映射到存储 selectedColumn 值的数组，并确保它们在结果中不重复。

【讨论】：

如果这是正确的，那么entityId/wellName 字段根本不重要。但是在上面的 cmets 中，提到了MARY，这让我怀疑这会在不同的数据上失败，如果说我们用Jan Feb / Jan 附加了另一个实体（比如JOSEPHS DRAW）。这将被排除在第一个副本之外。我认为这不是我们想要的。
非常正确，这会是@texas697 的问题吗？
我的答案通过从数据生成密钥来解决它。这并不总是可能的，但是当它起作用时，我发现它比使用这种手动检查更简单。
@ScottSauyet 你是对的。我确实遇到了这个问题。但是我能够解决问题的根源，不再需要快速解决

【解决方案2】：

我解决此类问题的一种方法是将我的列表临时折叠到一个对象中，其中键由对象的重要部分组成，并且值（在这种情况下）是现有结果（如果存在的话）或当前结果。这只是一个reduce 然后我只取这个对象的值，忽略键，使用Object .values。

这是一种方法：

const dedupe = data => Object .values (data .reduce ((
  a, entry, _, __, 
  key = `${entry .entityId} | ${entry .selectedColumn} | ${entry .selectedColumns}`
) => ({...a, [key]: a [key] || entry}), {}))

const DATA = [{wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "WAYZETTA 67-2536H", entityId: 31135395, selectedColumn: "Mar", selectedColumns: "Mar"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Jan", selectedColumns: "Jan Feb"}, {wellName: "MARYS DRAW 461-2227H", entityId: 31340479, selectedColumn: "Feb", selectedColumns: "Jan Feb"}];

console .log (dedupe (DATA))

根据数据，我假设我们只需要匹配entityId，即wellName 和entityId 始终相关。如果这是错误的，那么很容易将井名添加到键中。

这段代码唯一有点棘手的地方是将参数内的key 分配给reduce。我喜欢这种方法，因为它使我的函数体成为一个单一的表达式。但是在这里，在reduce 回调中，由于reduce 提供给您的第三和第四个参数（索引和数组），这有点尴尬。我只是通过提供未使用的参数_ 和__ 来忽略它们。但也可以是i 和arr 或其他任何东西。

【讨论】：