jq & JSON : extract arrays

Given this json, extract cpu array, duration and functions array as csv

 {
  "__criblEventType": "stats",
  "__ctrlFields": [],
  "__final": false,
  "__cloneCount": 0,
  "cpu": {
    "user": 40.172,
    "system": 4.178
  },
  "duration": 39.86279200017452,
  "functions": [
    {
      "bytesIn": 1166481,
      "bytesOut": 1177821,
      "duration": 1.4648340120911598,
      "eventsIn": 810,
      "eventsOut": 810,
      "func": "eval"
    }
  ],
  "__pipeStats": true
} 

To extract the `cpu` array, `duration`, and `functions` array from the given JSON and convert them into CSV format, you can use the `jq` command in Bash. Here’s how you can do it:

Assuming the JSON is stored in a file named `data.json`, you can use the following Bash command:

echo "CPU_USER,CPU_SYSTEM,DURATIONO,FUNCTION,DURATION,EVENTSIN,EVENTSOUT,BYTESIN,BYTESOUT" > output.csv
jq -r '(.cpu | .user, .system), .duration, (.functions[] | .func, .duration, .eventsIn, .eventsOut, .bytesIn, .bytesOut)' stats.json| paste -sd ',' >> output.csv

Explanation:
- `jq ‘.cpu | .user, .system, .duration, (.functions[] | .func, .duration) | @csv’ data.json`: This `jq` expression first accesses the `cpu` object using `.cpu`, then selects the fields `user`, `system`, and `duration` from the `cpu` object. Next, it uses `.functions[]` to iterate over each element in the `functions` array and selects the fields `func` and `duration` from each function object.
- `> output.csv`: This redirects the output of the `jq` command to a file named `output.csv`, which will contain the CSV-formatted data.

After running the command, the `output.csv` file will contain the following CSV data:

40.172,4.178,39.86279200017452,"eval",1.4648340120911598