python3 -- json档案处理

import json

处理JSON文件通常涉及读取、解析和写入JSON数据的过程。下面是一些在Python中处理JSON文件的常用方法：
1. 读取JSON文件：
使用Python内置的json模块可以轻松读取JSON文件。首先，需要导入json模块并打开文件，然后使用json.load()方法将JSON数据加载到Python对象中。

import json  
with open('example.json') as file:  
data = json.load(file)
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1. 解析JSON数据：
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一旦将JSON数据加载到Python对象中，就可以使用Python的语法对其进行处理。例如，可以访问嵌套的字典、列表和键值对等。

# 访问嵌套的字典  
name = data['person']['name']  
age = data['person']['age']  
# 访问列表  
scores = data['scores']  
score_1 = scores[0]  
# 遍历嵌套的字典和列表  
for student in data['students']:  
print(student['name'])  
print(student['age'])  
print(student['scores'])
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1. 修改JSON数据：
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可以根据需要对JSON数据进行修改。可以修改特定的键值对，添加新的键值对或删除现有的键值对。这里演示如何添加新的键值对。

data['person']['email'] = 'example@example.com'
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1. 写入JSON文件：
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使用json.dump()方法将修改后的Python对象写入JSON文件。同样需要使用Python内置的open()函数打开文件，指定写入模式，并使用json.dump()方法将数据写入文件。

with open('output.json', 'w') as file:  
json.dump(data, file)
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这些是处理JSON文件的基本步骤。根据你的具体需求，可能需要更复杂的逻辑来处理更复杂的JSON结构。

实战：
假设我有下面这份fio的json结果文档,叫做fio.json好了，我对其进行解析，抓我需要的write的IOPS和BW的结果

{
  "fio version" : "fio-3.1",
  "timestamp" : 1696925985,
  "timestamp_ms" : 1696925985515,
  "time" : "Tue Oct 10 16:19:45 2023",
  "jobs" : [
    {
      "jobname" : "128k_write_mix0_num1_iodepth64",
      "groupid" : 0,
      "error" : 0,
      "eta" : 0,
      "elapsed" : 301,
      "job options" : {
        "name" : "128k_write_mix0_num1_iodepth64",
        "filename" : "/dev/nvme0n1",
        "ioengine" : "libaio",
        "direct" : "1",
        "rw" : "write",
        "rwmixread" : "0",
        "bs" : "128k",
        "numjobs" : "1",
        "iodepth" : "64",
        "runtime" : "300",
        "time_based" : "1",
        "write_iops_log" : "./1010/128k_write_mix0_num1_iodepth64",
        "write_bw_log" : "./1010/128k_write_mix0_num1_iodepth64",
        "log_avg_msec" : "1000"
      },
      "read" : {
        "io_bytes" : 0,
        "io_kbytes" : 0,
        "bw" : 0,
        "iops" : 0.000000,
        "runtime" : 0,
        "total_ios" : 0,
        "short_ios" : 0,
        "drop_ios" : 0,
        "slat_ns" : {
          "min" : 0,
          "max" : 0,
          "mean" : 0.000000,
          "stddev" : 0.000000
        },
        "clat_ns" : {
          "min" : 0,
          "max" : 0,
          "mean" : 0.000000,
          "stddev" : 0.000000,
          "percentile" : {
            "1.000000" : 0,
            "5.000000" : 0,
            "10.000000" : 0,
            "20.000000" : 0,
            "30.000000" : 0,
            "40.000000" : 0,
            "50.000000" : 0,
            "60.000000" : 0,
            "70.000000" : 0,
            "80.000000" : 0,
            "90.000000" : 0,
            "95.000000" : 0,
            "99.000000" : 0,
            "99.500000" : 0,
            "99.900000" : 0,
            "99.950000" : 0,
            "99.990000" : 0,
            "0.00" : 0,
            "0.00" : 0,
            "0.00" : 0
          }
        },
        "lat_ns" : {
          "min" : 0,
          "max" : 0,
          "mean" : 0.000000,
          "stddev" : 0.000000
        },
        "bw_min" : 0,
        "bw_max" : 0,
        "bw_agg" : 0.000000,
        "bw_mean" : 0.000000,
        "bw_dev" : 0.000000,
        "bw_samples" : 0,
        "iops_min" : 0,
        "iops_max" : 0,
        "iops_mean" : 0.000000,
        "iops_stddev" : 0.000000,
        "iops_samples" : 0
      },
      "write" : {
        "io_bytes" : 995677306880,
        "io_kbytes" : 972341120,
        "bw" : 3241104,
        "iops" : 25321.130122,
        "runtime" : 300003,
        "total_ios" : 7596415,
        "short_ios" : 0,
        "drop_ios" : 0,
        "slat_ns" : {
          "min" : 3449,
          "max" : 120791,
          "mean" : 9509.510472,
          "stddev" : 4055.313047
        },
        "clat_ns" : {
          "min" : 275173,
          "max" : 26670061,
          "mean" : 2517367.006916,
          "stddev" : 1031195.720264,
          "percentile" : {
            "1.000000" : 1056768,
            "5.000000" : 1253376,
            "10.000000" : 1368064,
            "20.000000" : 1630208,
            "30.000000" : 1892352,
            "40.000000" : 2146304,
            "50.000000" : 2408448,
            "60.000000" : 2670592,
            "70.000000" : 2867200,
            "80.000000" : 3129344,
            "90.000000" : 3817472,
            "95.000000" : 4358144,
            "99.000000" : 5734400,
            "99.500000" : 6455296,
            "99.900000" : 8454144,
            "99.950000" : 9371648,
            "99.990000" : 15269888,
            "0.00" : 0,
            "0.00" : 0,
            "0.00" : 0
          }
        },
        "lat_ns" : {
          "min" : 279136,
          "max" : 26675989,
          "mean" : 2526944.836070,
          "stddev" : 1031563.153543
        },
        "bw_min" : 1596160,
        "bw_max" : 3427584,
        "bw_agg" : 99.997880,
        "bw_mean" : 3241035.300000,
        "bw_dev" : 309378.872013,
        "bw_samples" : 300,
        "iops_min" : 12470,
        "iops_max" : 26778,
        "iops_mean" : 25320.580000,
        "iops_stddev" : 2417.018326,
        "iops_samples" : 300
      },
      "trim" : {
        "io_bytes" : 0,
        "io_kbytes" : 0,
        "bw" : 0,
        "iops" : 0.000000,
        "runtime" : 0,
        "total_ios" : 0,
        "short_ios" : 0,
        "drop_ios" : 0,
        "slat_ns" : {
          "min" : 0,
          "max" : 0,
          "mean" : 0.000000,
          "stddev" : 0.000000
        },
        "clat_ns" : {
          "min" : 0,
          "max" : 0,
          "mean" : 0.000000,
          "stddev" : 0.000000,
          "percentile" : {
            "1.000000" : 0,
            "5.000000" : 0,
            "10.000000" : 0,
            "20.000000" : 0,
            "30.000000" : 0,
            "40.000000" : 0,
            "50.000000" : 0,
            "60.000000" : 0,
            "70.000000" : 0,
            "80.000000" : 0,
            "90.000000" : 0,
            "95.000000" : 0,
            "99.000000" : 0,
            "99.500000" : 0,
            "99.900000" : 0,
            "99.950000" : 0,
            "99.990000" : 0,
            "0.00" : 0,
            "0.00" : 0,
            "0.00" : 0
          }
        },
        "lat_ns" : {
          "min" : 0,
          "max" : 0,
          "mean" : 0.000000,
          "stddev" : 0.000000
        },
        "bw_min" : 0,
        "bw_max" : 0,
        "bw_agg" : 0.000000,
        "bw_mean" : 0.000000,
        "bw_dev" : 0.000000,
        "bw_samples" : 0,
        "iops_min" : 0,
        "iops_max" : 0,
        "iops_mean" : 0.000000,
        "iops_stddev" : 0.000000,
        "iops_samples" : 0
      },
      "usr_cpu" : 16.971887,
      "sys_cpu" : 16.700555,
      "ctx" : 3797071,
      "majf" : 0,
      "minf" : 10,
      "iodepth_level" : {
        "1" : 0.100000,
        "2" : 0.100000,
        "4" : 0.100000,
        "8" : 0.100000,
        "16" : 0.100000,
        "32" : 0.100000,
        ">=64" : 99.999171
      },
      "latency_ns" : {
        "2" : 0.000000,
        "4" : 0.000000,
        "10" : 0.000000,
        "20" : 0.000000,
        "50" : 0.000000,
        "100" : 0.000000,
        "250" : 0.000000,
        "500" : 0.000000,
        "750" : 0.000000,
        "1000" : 0.000000
      },
      "latency_us" : {
        "2" : 0.000000,
        "4" : 0.000000,
        "10" : 0.000000,
        "20" : 0.000000,
        "50" : 0.000000,
        "100" : 0.000000,
        "250" : 0.000000,
        "500" : 0.010000,
        "750" : 0.032186,
        "1000" : 0.438352
      },
      "latency_ms" : {
        "2" : 34.327943,
        "4" : 57.133003,
        "10" : 8.031209,
        "20" : 0.030922,
        "50" : 0.010000,
        "100" : 0.000000,
        "250" : 0.000000,
        "500" : 0.000000,
        "750" : 0.000000,
        "1000" : 0.000000,
        "2000" : 0.000000,
        ">=2000" : 0.000000
      },
      "latency_depth" : 64,
      "latency_target" : 0,
      "latency_percentile" : 100.000000,
      "latency_window" : 0
    }
  ],
  "disk_util" : [
    {
      "name" : "nvme0n1",
      "read_ios" : 44,
      "write_ios" : 7593512,
      "read_merges" : 0,
      "write_merges" : 0,
      "read_ticks" : 4,
      "write_ticks" : 19039100,
      "in_queue" : 18805644,
      "util" : 100.000000
    }
  ]
}
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with open('fio.json') as file:  
	data = json.load(file)
#这里的data['jobs'][0]代表取字典jobs的值后，是一个[],看作为List，需要取list里面的值，我们这里只有一个，取[0],取到以后再取key ['write'],在这个字典下取key['iops'],则可以拿到对应的iops的值
iops = data['jobs'][0]['write']['iops']
bw = data['jobs'][0]['write']['bw']
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这里我们最后 iops和bw的值分别为：25321.130122 和 3241104
感兴趣可以一个一个试，看输出的是什么：
即打印

print(data['jobs'])
print(data['jobs'][0])
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以此类推，观察每一步有啥输出，有助理解