模块json：处理JSON数据

JSON (JavaScript Object Notation)是一种轻量级的数据交换格式，易于人阅读和编写，同时也易于机器解析和生成。

JSON 基础

JSON 的基础结构有两种：键值对 (name/value pairs) 和数组 (array)。

JSON 具有以下形式：

• object - 对象，用花括号表示，形式为（数据是无序的）：
  • { pair_1, pair_2, ..., pair_n }
• pair - 键值对，形式为：
  • string : value
• array - 数组，用中括号表示，形式为（数据是有序的）：
  • [value_1, value_2, ..., value_n ]
• value - 值，可以是
  • string 字符串
  • number 数字
  • object 对象
  • array 数组
  • true / false / null 特殊值
  • string 字符串

例子：

{
    "name": "echo",
    "age": 24,
    "coding skills": ["python", "matlab", "java", "c", "c++", "ruby", "scala"],
    "ages for school": { 
        "primary school": 6,
        "middle school": 9,
        "high school": 15,
        "university": 18
    },
    "hobby": ["sports", "reading"],
    "married": false
}

JSON 与 Python 的转换

将上面的结构放入字符串：

info_string = """
{
    "name": "echo",
    "age": 24,
    "coding skills": ["python", "matlab", "java", "c", "c++", "ruby", "scala"],
    "ages for school": { 
        "primary school": 6,
        "middle school": 9,
        "high school": 15,
        "university": 18
    },
    "hobby": ["sports", "reading"],
    "married": false
}
"""

使用json模块读取数据：

import json

data = json.loads(info_string)

data

{'name': 'echo',
 'age': 24,
 'coding skills': ['python', 'matlab', 'java', 'c', 'c++', 'ruby', 'scala'],
 'ages for school': {'primary school': 6,
  'middle school': 9,
  'high school': 15,
  'university': 18},
 'hobby': ['sports', 'reading'],
 'married': False}

将这个对象转换为JSON字符串：

print(json.dumps(info_string))

"\n{\n    \"name\": \"echo\",\n    \"age\": 24,\n    \"coding skills\": [\"python\", \"matlab\", \"java\", \"c\", \"c++\", \"ruby\", \"scala\"],\n    \"ages for school\": { \n        \"primary school\": 6,\n        \"middle school\": 9,\n        \"high school\": 15,\n        \"university\": 18\n    },\n    \"hobby\": [\"sports\", \"reading\"],\n    \"married\": false\n}\n"

读写JSON文件

写JSON文件：

with open("info.json", "w") as f:
    json.dump(data, f)

查看文件内容：

with open("info.json") as f:
    print(f.read())

{"name": "echo", "age": 24, "coding skills": ["python", "matlab", "java", "c", "c++", "ruby", "scala"], "ages for school": {"primary school": 6, "middle school": 9, "high school": 15, "university": 18}, "hobby": ["sports", "reading"], "married": false}

读JSON文件：

with open("info.json") as f:
    info = json.load(f)

info

{'name': 'echo',
 'age': 24,
 'coding skills': ['python', 'matlab', 'java', 'c', 'c++', 'ruby', 'scala'],
 'ages for school': {'primary school': 6,
  'middle school': 9,
  'high school': 15,
  'university': 18},
 'hobby': ['sports', 'reading'],
 'married': False}

删除临时文件：

%rm info.json