如何使用索引符号访问对象[重复]

Question

我正在尝试使用表格数据制作一个对象

 var cond = [
        { 
    "locality": "Dwarka",
    "Created ->OFP": "4.73",
    "OFP -> Picked": "2.16",
    "Picked - > Delivery": "14.91",
    "Over_All_TAT": "22.65",
    "Total_Order": "159" 
  },
  {
    "locality": "IIT & AIIMS",
    "Created ->OFP": "2.56",
    "OFP -> Picked": "9.74",
    "Picked - > Delivery": "19.41",
    "Over_All_TAT": "32.61",
    "Total_Order": "54"
  },
  {
    "locality": "Gk1 & Nehru Place",
    "Created ->OFP": "2.39",
    "OFP -> Picked": "6.87",
    "Picked - > Delivery": "14.06",
    "Over_All_TAT": "24.13",
    "Total_Order": "31"
  },
  {
    "locality": "Mayur Vihar",
    "Created ->OFP": "3.52",
    "OFP -> Picked": "1.24",
    "Picked - > Delivery": "15.3",
    "Over_All_TAT": "21.03",
    "Total_Order": "33"
  },
  {
    "locality": "Snapdeal_Mundhka",
    "Created ->OFP": "17.32",
    "OFP -> Picked": "4.65",
    "Picked - > Delivery": "100.32",
    "Over_All_TAT": "123.16",
    "Total_Order": "31"
  }
  ]

我知道键名不符合规则，但那些是列名。我可以访问第二列说 Created -> OFP using index（例如cond[0][1]）。

我只能访问 cond[i] 我如何访问内部块元素。

当我使用 R 时，json 对象是使用 jsonlite 包创建的，所以，我有限制。

Answer 1

您可以像这样访问内部块：

cond[i]['Created ->OFP']

循环示例：

var cond = [{
  "locality": "Dwarka",
  "Created ->OFP": "4.73",
  "OFP -> Picked": "2.16",
  "Picked - > Delivery": "14.91",
  "Over_All_TAT": "22.65",
  "Total_Order": "159"
}, {
  "locality": "IIT & AIIMS",
  "Created ->OFP": "2.56",
  "OFP -> Picked": "9.74",
  "Picked - > Delivery": "19.41",
  "Over_All_TAT": "32.61",
  "Total_Order": "54"
}, {
  "locality": "Gk1 & Nehru Place",
  "Created ->OFP": "2.39",
  "OFP -> Picked": "6.87",
  "Picked - > Delivery": "14.06",
  "Over_All_TAT": "24.13",
  "Total_Order": "31"
}, {
  "locality": "Mayur Vihar",
  "Created ->OFP": "3.52",
  "OFP -> Picked": "1.24",
  "Picked - > Delivery": "15.3",
  "Over_All_TAT": "21.03",
  "Total_Order": "33"
}, {
  "locality": "Snapdeal_Mundhka",
  "Created ->OFP": "17.32",
  "OFP -> Picked": "4.65",
  "Picked - > Delivery": "100.32",
  "Over_All_TAT": "123.16",
  "Total_Order": "31"
}]
var val;
cond.forEach(function(el) {
  val = el['Created ->OFP'];
  console.log(val);
});

Answer 2

据我了解，您希望能够做的事情是：

cond[0][1];   // "4.73"

您不能这样做，因为cond[0] 是和对象，并且不能保证对象中键的顺序。因此，仅仅因为Created ->OFP 是您输入的第二个键 并不意味着它实际上是对象中的第二个键。您可以查看Object.keys(cond[0])，密钥可能会以相同的顺序返回，但您不能依赖此。

听起来您需要做的是将数组中的对象（不是其他人指出的 JSON）转换为数组本身。所以你最终会得到类似的东西：

[
    [
        "Dwarka",
        "4.73",
        "2.16",
        "14.91",
        "22.65",
        "159"
    ],...
]

然后你可以这样做：

cond[0][1];   //and get the first row and second column.

要将您的原始数据转换为数组数组，您可以执行以下操作：

// Note: this is the order **you** want the columns to be iterated in
var columns = ["locality",
    "Created ->OFP",
    "OFP -> Picked",
    "Picked - > Delivery",
    "Over_All_TAT",
    "Total_Order"];

var arrayOfArrays = cond.map(function (i) {
    return columns.map(function (prop) {
        return i[prop];
    });
});

console.log(arrayOfArrays[0][1]);   // logs 4.73

Fiddle

Answer 3

你可以像这样访问你的元素：

cond[i]["Created ->OFP"]; // "4.73"

---

如果你想使用像 1、2 这样的索引，你有两个选择： 使用数组而不是对象，它看起来像这样：

 var cond = [
        ["Dwarka", "4.73", "2.16", "14.91", "22.65", "159" ],
        [ ... ]
  }

或者您可以在对象上使用索引 1、2 ...，如下所示：

var cond = [
        { 
    "0": "Dwarka",
    "1": "4.73",
    "2": "2.16",
    "3": "14.91",
    "4": "22.65",
    "5": "159" 
  },
  {...}
]

但您不会找到属性length，除非您将其作为元素添加到您的对象中。

---

我认为对你来说最好的解决方案是保持你的对象不变，并使用循环for(key in cond)

for(var i=0; i<cond.length; i++) {
    for(var key in cond[i]) {
       console.log(cond[i][key]);
    }
}