怎么读一整行，然后只读最后五个字呢？

Question

我是Python新手。我想从监视中读取一个JSON文件。该文件如下所示

我只需要时间戳、系统名(如"test-1“)以及电源、磁盘和CPU的编号。

我的剧本看上去像这样

#!/usr/bin/env python3.3

import os
import json 

    with open('test.json', 'r') as f:
        distros_dict = json.load(f)

    for distro in distros_dict:
        print(distro['"power [W]"'])

更新:如何将它们写入变量？

新的样本数据：

[
   {
      "Area":"CLOUD",
      "timestamp":"2019-11-06T00:00:00",
      "Systeme":{
         "test-4":{
            "power [W]":181.05,
            "disk [%]":52.28
         },
         "test-1":{
            "power [W]":280.56,
            "disk[%]":6.33,
            "cpu[%]":0.1
         },
         "test-2":{
            "power [W]":271.84,
            "disk[%]":6.52,
            "cpu[%]":0.1
         },      
         "test-8":{
            "power [W]":453.56,
            "disk[%]":93.63,
            "cpu[%]":5.04
         }
      }
   }
]

我想要的输出变量是cpu、power和磁盘，而不是将它们打印到命令行，而是将它们写入三个变量中。

Answer 1

可以使用元组列表来存储变量。下面是你如何做到这一点的一个例子。

import json
import sys

data = None

with open('test.json', 'r') as file:
    data = json.load(file)

# since we are dealing with input from another source, we should validate it every step of the way
# check if there was no data in the file
if not data:
    sys.exit(0)



variables = []  # this list would contain tuples. The tuple would contain system name, cpu, power, and disk. Any missing data would be set as None
for distro in data:
    if 'Systeme' not in distro:  # we verify this attribute exists
        continue
    for system_name, system in distro['Systeme'].items():
         variables.append( 
             (system_name, system.get('cpu[%]'), system.get('power [W]'), system.get('disk[%]'))
         )

# now that we have them stored inside the 'variables' list, we can print them to verify that they are stored.
for system_name, cpu, power, disk in variables:
    print(system_name, cpu, power, disk)
    # do other stuff with these variables here if you want.

Answer 2

您的带有多个dict的json文件应该遵循以下格式：

[    
    { 
        "Area": "CLOUD",
        "timestamp": "2019-11-06T12:24:25",
        "Systeme": {
            "test-1": {
                "power [W]": 181.05,
                "disk [%]": 52.28
            },
            "test-2": {
                "power [W]": 199.67,
                "disk [%]": 54.47
            },
            "test-3": {
                "power [W]": 175.68,
                "disk [%]": 10.17,
                "cpu [%]": 22.43
            }
        }
    },
    { 
        "Area": "CLOUD",
        "timestamp": "2019-11-06T12:24:25",
        "Systeme": {
            "test-1": {
                "power [W]": 181.05,
                "disk [%]": 52.28
            },
            "test-2": {
                "power [W]": 199.67,
                "disk [%]": 54.47
            },
            "test-3": {
                "power [W]": 175.68,
                "disk [%]": 10.17,
                "cpu [%]": 22.43
            }
        }
    }
]

您只需将每个字典中的值组合成一个字符串即可得到如下结果：

with open('test.json', 'r') as f:
    distros_dict = json.load(f)

test_keys = ['power [W]', 'disk [%]', 'cpu [%]']

for distro in distros_dict:
    for key, value in distro['Systeme'].items():
        output_list =[]
        output_list.append(key)
        for single_system_key, single_system_value in distro['Systeme'][key].items():
           if single_system_key in test_keys:
              output_list.append(single_system_value)
        print(' - '.join(str(e) for e in output_list))

最终输出得到：

test-1 - 181.05 - 52.28
test-2 - 199.67 - 54.47
test-3 - 175.68 - 10.17 - 22.43
test-1 - 181.05 - 52.28
test-2 - 199.67 - 54.47
test-3 - 175.68 - 10.17 - 22.43

Answer 3

设置您的字典(json格式，检查它是否在https://jsonlint.com/上使用正确的格式)

dict = {
  "Area": "CLOUD",
    "timestamp": "2019-11-06T12:24:25",
    "Systeme": {
        "test-1": {
            "power [W]": 181.05,
            "disk [%]": 52.28
        },
        "test-2": {
            "power [W]": 199.67,
            "disk [%]": 54.47
        },
        "test-3": {
            "power [W]": 175.68,
            "disk [%]": 10.17,
             "cpu [%]": 22.43
}}}

以json的形式加载字典

import json
x = json.loads(json.dumps(dict))

循环遍历您的dictSysteme并获取您需要打印的所有属性。我选择使用dict.get("systeme")而不是dict["Systeme"]，因为测试3中缺少cpu

for line in x["Systeme"]:
    power = x.get("Systeme").get(line).get("power [W]", "")
    disk = x.get("Systeme").get(line).get("disk [%]", "")
    cpu = x.get("Systeme").get(line).get("cpu [%]", "")
    print(f"{line} {power} {disk} {cpu}")
    power, disk, cpu = "", "", ""

注意:上面的示例是Python 3.7+，需要将print语句更改为Python的早期版本：

print("%s %s %s %s"%(line, power, disk, cpu) )