基于匹配键合并两个多维数组？

Question

所以目前我正在生成应该组合在一起形成以下 JSON 的记录：

{
  "Monday": [{
      "Index": "1",
      "To": "200",
      "From": "1200"
    },
    {
      "Index": "2",
      "To": "1300",
      "From": "1400"
    }
  ],
  "Tuesday": [{
      "Index": "1",
      "To": "100",
      "From": "200"
    },
    {
      "Index": "2",
      "To": "1000",
      "From": "1200"
    },
    {
      "Index": "3",
      "To": "1300",
      "From": "1500"
    }
  ]
}

但目前，输出看起来更像这样：

如您所见，正在创建两条共享相同“索引”值的记录——这主要是因为我还没有弄清楚如何使用where index = <index> insert 来处理查找具有匹配索引的记录并添加属性给它。

目前，代码如下-

var controlsJson;
//Assume two loops are running through different sets of values for "type". setting them to "To" and "From" pragmatically.
//Array building
if (controlsJson == null) {
  controlsJson = [];
}
if (controlsJson[date] == null) {
  controlsJson[date] = [];
}
var pusher = [];
pusher["Index"] = index;
pusher[type] = time;
controlsJson[date].push(pusher);

除了解决匹配索引键的问题之外，我还有其他方法可以改进吗？

Answer 1

如果您改为以以下格式表示您的数据，这将更容易遍历：

let state = {
  Monday: {
    1: {
      To: 200,
      From: 1200
    },
    2: {
      To: 1300,
      From: 1400
    }
  },
  Tuesday: {
    1: {
      To: 100,
      From: 200
    },
    2: {
      To: 1000,
      From: 1200
    },
    3: {
      To: 1300,
      From: 1500
    }
  }
}

state = { ...state, Tuesday: { ...state.Tuesday, 2: { To: 1500, From: 1400 } } }

console.log(state)

如果您不关心不变性，以下方法也可以：

let state = {
  Monday: {
    1: {
      To: 200,
      From: 1200
    },
    2: {
      To: 1300,
      From: 1400
    }
  },
  Tuesday: {
    1: {
      To: 100,
      From: 200
    },
    2: {
      To: 1000,
      From: 1200
    },
    3: {
      To: 1300,
      From: 1500
    }
  }
}

state["Tuesday"][2] = { To: 1500, From: 1400 };

console.log(state)

Answer 2

正如 cchamberlain 所指出的，我处理索引的方式比真正需要的要复杂得多。

我将我的代码修改为以下内容并使用不可变的方法（我认为这就是所谓的），只需使用索引就可以实用地添加记录！

//Array building
if (controlsJson == null) {
    controlsJson = [];
}
if (controlsJson[date] == null) {
    controlsJson[date] = [];
}

if (controlsJson[date][index] == null) {
    controlsJson[date][index] = [];
}

controlsJson[date][index][type] = time;
}

另外请注意，如果您希望使用 JSON.Stringify，您需要将 = [] 更改为 = {}

再一次——如果你摔倒了，我可以进一步改进这段代码，请告诉我。

Answer 3

如果每天的索引都从 0 开始，这个小 sn-p 应该可以解决问题：

// your object that you start with
var days = {
    'Monday': [
        {Index: 0, Start: 330},
        {Index: 0, End: 1330},
        {Index: 1, Start: 330},
        {Index: 1, End: 1330},
        {Index: 2, Start: 330},
        {Index: 2, End: 1330},
    ],
    'Tuesday': [
        {Index: 0, Start: 330},
        {Index: 0, End: 1330},
        {Index: 1, Start: 330},
        {Index: 1, End: 1330},
        {Index: 2, Start: 330},
        {Index: 2, End: 1330},
        {Index: 3, Start: 330},
        {Index: 3, End: 1330},
    ],
};

// create an array of indexes. For each index, filter days by that Index,
// then pass those to Object.assign to merge the 2 items together.
var i, dayMaxIndex;
for (i in days) {
    if (days.hasOwnProperty(i)) {
        dayMaxIndex = Math.max.apply(null, days[i].map(function(d) { return d.Index; }));
        days[i] = Array.from({length: dayMaxIndex+1}, (v, i) => i).map(function(d) {
            return Object.assign.apply(null, days[i].filter(function(day) {
                return day.Index == d;
            }));
        });
    }
}
console.log(days);

您可以准备更多关于 Object.assign here。

我发现这篇文章有点令人困惑：

Array.from({length: dayMaxIndex+1}, (v, i) => i)

它生成一个序列号数组，从 0 开始，到 dayMaxIndex 结束。 Here's 我在哪里找到了这个例子。