title: Finding max value in multidimensional in mongodb
body: <p>if I have this collection </p>
  
  <pre><code>{ "humidity" : 96.5812, "temperature" : 10.5006 }
  { "humidity" : 97.1184, "temperature" : 10.2808 }
  { "humidity" : 96.2882, "temperature" : 8.4493 }
  { "humidity" : 97.8266, "temperature" : 7.4481 }
  { "humidity" : 98.9255, "temperature" : 7.2772 }
  { "humidity" : 99.4628, "temperature" : 7.3993 }
  { "humidity" : 99.4383, "temperature" : 7.4237 }
  { "humidity" : 99.6825, "temperature" : 7.1307 }
  { "humidity" : 99.5116, "temperature" : 6.1539 }
  { "humidity" : 99.8779, "temperature" : 5.4701 }
  </code></pre>
  
  <p>how I can get the max and min value of temperature with mapreduce?</p>