将JSON数据解析为Python

Question

我有一个JSON文件，其中包含一些我需要的数据。我想写一个python程序来读取它并获取信息。有什么帮助吗？

下面是JSON的一个示例

var case_data = {
  "cases": {
    "1": {
      "amount": 1500.0, 
      "case_id": "1", 
      "case_name": "US v. Control Systems Specialist, Inc. and Darrold Richard Crites", 
      "country": "br", 
      "sector": "sector-defense"
    }, 
    "10": {
      "amount": 0.0, 
      "case_id": "10", 
      "case_name": "SEC v. Int'l Systems & Controls Corp.", 
      "country": "cl", 
      "sector": "sector-agriculture"
    }
  }, 
  "countries": {
    "ae": {
      "cases": [
        "191", 
        "192", 
        "193", 
        "282", 
        "332"
      ], 
      "sectors": {
        "sector-consulting": {
          "total": 1812113.33
        }, 
        "sector-energy": {
          "total": 6622147.0
        }, 
        "sector-infrastructure": {
          "total": 4694551.0
        }
      }, 
      "total": 13128811.33, 
      "tree": {
        "children": [
          {
            "children": [], 
            "classname": "sector-energy", 
            "data": {
              "$amount": 4550000.0, 
              "$area": 3
            }, 
            "id": "191", 
            "name": "Control Components Inc. et al."
          }, 
          {
            "children": [], 
            "classname": "sector-infrastructure", 
            "data": {
              "$amount": 140551.0, 
              "$area": 2
            }, 
            "id": "192", 
            "name": "Textron Inc."
          }, 
          {
            "children": [], 
            "classname": "sector-infrastructure", 
            "data": {
              "$amount": 4554000.0, 
              "$area": 3
            }, 
            "id": "193", 
            "name": "York International Corp."
          }, 
          {
            "children": [], 
            "classname": "sector-consulting", 
            "data": {
              "$amount": 1812113.33, 
              "$area": 3
            }, 
            "id": "282", 
            "name": "Aon Corporation"
          }, 
          {
            "children": [], 
            "classname": "sector-energy", 
            "data": {
              "$amount": 2072147.0, 
              "$area": 3
            }, 
            "id": "332", 
            "name": "Tyco Int\u2019l Ltd. et al."
          }
        ], 
        "data": {
          "$amount": 0, 
          "$area": 14
        }, 
        "id": "ae", 
        "name": "UAE"
      }
    }, 
    "ao": {
      "cases": [
        "5", 
        "9", 
        "207", 
        "208", 
        "209"
      ], 
      "sectors": {
        "sector-consulting": {
          "total": 12350000.0
        }, 
        "sector-energy": {
          "total": 18097043.0
        }, 
        "sector-telecom": {
          "total": 7080000.0
        }
      }, 
      "total": 37527043.0, 
      "tree": {
        "children": [
          {
            "children": [], 
            "classname": "sector-energy", 
            "data": {
              "$amount": 302043.0, 
              "$area": 2
            }, 
            "id": "5", 
            "name": "ABB Ltd. et al."
          }, 
          {
            "children": [], 
            "classname": "sector-energy", 
            "data": {
              "$amount": 16335000.0, 
              "$area": 6
            }, 
            "id": "9", 
            "name": "Baker Hughes Inc. et al."
          }, 
          {
            "children": [], 
            "classname": "sector-energy", 
            "data": {
              "$amount": 1460000.0, 
              "$area": 3
            }, 
            "id": "207", 
            "name": "GlobalSanteFe Corp."
          }, 
          {
            "children": [], 
            "classname": "sector-telecom", 
            "data": {
              "$amount": 7080000.0, 
              "$area": 3
            }, 
            "id": "208", 
            "name": "Alcatel-Lucent S.A. et al."
          }, 
          {
            "children": [], 
            "classname": "sector-consulting", 
            "data": {
              "$amount": 12350000.0, 
              "$area": 6
            }, 
            "id": "209", 
            "name": "Panalpina World Transport (Holding) Ltd. et al."
          }
        ], 
        "data": {
          "$amount": 0, 
          "$area": 20
        }, 
        "id": "ao", 
        "name": "Angola"
      }
    }, 
  };

我想提取每个国家“部门-能源”后面的数字。请注意，在此示例文件中，有两个国家/地区'ae‘和'ao’。

Answer 1

如果你真的有JSON。您所能做的就是使用json模块将其解码为本机dict，就像使用JavaScript中的JSON对象将其解码为本机object一样。比较这个JS：

var case_data = JSON.parse(data);

…等效于Python：

case_data = json.loads(data)

完成此操作后，就不再需要担心JSON了；它只是普通的本机对象，您可以像访问字典、列表、字符串和数字的任何其他组合一样访问这些对象。例如：

sector_energy = [country["sectors"]["sector-energy"] 
                 for country in case_data["countries"]]

但是，您向我们展示的根本不是JSON；它是JavaScript源代码，它将一个复杂的对象赋给一个变量。您不能在任何语言中将其解析为JSON，因为它不是。

当然，=和;之间的源代码部分不仅是有效的JavaScript代码，也是有效的JSON。就此而言，它也是有效的Python和有效的Ruby。但是，如果您想要解析这个文件和其他类似的文件，则需要制定规则，以确定哪些片段代表您想要解析的JSON。每个文件是否只有一个JS变量赋值？或者是其他的东西？

无论如何，实际上使用JSON进行语言之间的交换要好得多，而不是使用某种类似JSON的东西并希望它能正常工作。

Answer 2

Python已经为此提供了一个库

http://docs.python.org/3.3/library/json.html