input.json

[{"id": "a","timestamp": 1509493641,"temperature": 3.53},
    {"id": "b","timestamp": 1509493642,"temperature": 4.13},
    {"id": "c","timestamp": 1509493643,"temperature": 3.96},
    {"id": "a","timestamp": 1509493644,"temperature": 3.63},
    {"id": "c","timestamp": 1509493645,"temperature": 3.96},
    {"id": "a","timestamp": 1509493645,"temperature": 4.63},
    {"id": "a","timestamp": 1509493646,"temperature": 3.53},
    {"id": "b","timestamp": 1509493647,"temperature": 4.15},
    {"id": "c","timestamp": 1509493655,"temperature": 3.95},
    {"id": "a","timestamp": 1509493677,"temperature": 3.66},
    {"id": "b","timestamp": 1510113646,"temperature": 4.15},
    {"id": "c","timestamp": 1510127886,"temperature": 3.36},
    {"id": "c","timestamp": 1510127892,"temperature": 3.36},
    {"id": "a","timestamp": 1510128112,"temperature": 3.67},
    {"id": "b","timestamp": 1510128115,"temperature": 3.88}]