title: JSON sum values of a key where there are more keys with the same name PHP
body: <p>I am playing with some air quality data where each results contains at least 2 results. I know that I can limit the loop and get the data from the last entry only, but would have been very nice if I can actually sum the values of the same keys and divide the result by the number of entries, so I can get more precise value.<a href="https://i.stack.imgur.com/lOHBg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lOHBg.png" alt="enter image description here"></a></p>
  
  <p>A problem that I see there is that the key value for P1 and P2 are within the same array so no idea how to sum the two keys separately</p>
  
  <p>The difference between the values in two sets of P1 and P2 keys is coming from the timestamp of the data. </p>
  
  <p>Any idea how can I achieve that?</p>
  
  <p>Here is the JSON data</p>
  
  <pre><code>[{"sensor":{"sensor_type":{"name":"SDS011","manufacturer":"Nova Fitness","id":14},"pin":"1","id":19770},"sensordatavalues":[{"value_type":"P1","value":"250.80","id":6323692330},{"value_type":"P2","value":"68.70","id":6323692332}],"location":{"country":"BG","latitude":"41.9460","altitude":"229.5","longitude":"25.5380","id":10044},"sampling_rate":null,"timestamp":"2019-02-26 14:02:34","id":2977869281},{"sensor":{"sensor_type":{"name":"SDS011","manufacturer":"Nova Fitness","id":14},"pin":"1","id":19770},"sensordatavalues":[{"value_type":"P1","value":"106.87","id":6323721400},{"value_type":"P2","value":"34.80","id":6323721402}],"location":{"country":"BG","latitude":"41.9460","altitude":"229.5","longitude":"25.5380","id":10044},"sampling_rate":null,"timestamp":"2019-02-26 14:05:04","id":2977883059}]
  </code></pre>