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Json – Jmespath to get key and value only for specific key names

I have a Json file with multiple measurements, I want to get only "wind_speed_avg" values, if there is a value then get also the "ts" value and add the lsid but it is not in the same path.

The JSON looks like this:

    {'station_id_uuid': 'd0d1a311', 
    'sensors': [
         {'lsid': 3531, 
          'data': [
             {'bar_absolute': 29.836, 
              'bar_hi_at': 1727761555, 
              'ts': 1727762400
             }
           ], 
         'sensor_type': 242, 
         'data_structure_type': 13
         }, 
        {'lsid': 3558, 
        'data': [
            {'wind_speed_avg': 10, 
             'uv_dose': 0.12857144, 
             'wind_chill_last': 66.5, 
             'ts': 1727763300
            },
           {'wind_speed_avg': 12, 
            'uv_dose': 0.096428566,
            'wind_chill_last': 65.8, 
            'ts': 1727762896
           }, 
           {'wind_speed_avg': 8.75, 
            'uv_dose': 0.074999996, 
            'wind_chill_last': 66.1, 
            'ts': 1727763665          
           }
        ], 
        'sensor_type': 43, 
        'data_structure_type': 11
      }
   ], 
    'generated_at': 1734604671, 
    'station_id': 988
 }

I`m using this python script:

data = jmespath.search("""
        sensors[].{
        value: data[].wind_speed_avg,
        time: data[].ts,
        sensor_id: lsid
        }
        """, json_data)

and the result I`m getting is this:

[
 {'value': [], 'time': [1727762400], 'sensor_id': 3531}, 
 {'value': [10, 12, 8.75], 'time': [1727763300, 1727762896, 1727763665], 'sensor_id': 3558}
]

I want the result to be this way:

[
     {'value': None, 'time': 1727762400, 'sensor_id': 3531}, 
     {'value': 10, 'time': 1727763300, 'sensor_id': 3558},
    {'value': 12, 'time': 1727762896,'sensor_id': 3558},
    {'value': 8.75, 'time': 1727763665,'sensor_id': 3558},
 ]

I want to add the node sensor_id to the dictionary.
Any ideas how can I do it?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Finally I found a way to do what I needed, this is the function I used:

     def filter_measurement(stationid, measure, input_json):
        if input_json:
    
            data = jmespath.search("""
               sensors[].{
               value: data[].""" + measure + """,
               time: data[].ts,
               sensor_id: lsid
               }
               """, input_json)
    
            result_dic = []
    
            for i in data:
                if i["value"]:
                    num_values = len(i["value"])
                    for val in range(num_values):
                        date_val = datetime.fromtimestamp(i["time"][val])
                        result_dic.append({"station_id": stationid, "sensor_id": i["sensor_id"], "measurement": measure, "datetime": str(date_val), "Year": date_val.year, "Month": date_val.month, "Day": date_val.day, "Hour": date_val.hour, "Minute": date_val.minute, "value": i["value"][val]})
            return result_dic

  2. 0

    Instead of the loops, you can use comprehensions. For example,

    result = [{'value': j[0], 'time': j[1], 'sensor_id': i['sensor_id']}
          for i in data
          for j in zip(i['value'], i['time'])
          if i['value']]

    gives

    [
 {'value': 10, 'time': 1727763300, 'sensor_id': 3558},
 {'value': 12, 'time': 1727762896, 'sensor_id': 3558},
 {'value': 8.75, 'time': 1727763665, 'sensor_id': 3558}
]
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