title: How to merge multiple arrays in python?
body: <p>I'd like to read the content of multiple files, process their data individually (because of performance and hardware resources) and write my results into one 'big' netCDF4 file.</p>
  
  <p>Right now I'm able to read the files, process their data, but I struggle with the resulting multiple arrays. I wasn't able to merge them correctly.</p>
  
  <p>I've got a 3d array (time,long,lat) containing my calculated value for each day. What I like to do is to merge all the arrays I've got into one big array before I write it into my netCDF4 file. (all days in one array)</p>
  
  <p>Here two example arrays:</p>
  
  <ul>
  <li>day1[19790101][-25][35]=95</li>
  <li>day2[19790102][-15][25]=93</li>
  </ul>
  
  <p>My expected result is:</p>
  
  <ul>
  <li>allDays[19790101][-25][35]=95</li>
  <li>allDays[19790102][-15][25]=93</li>
  </ul>
  
  <p>How can I achive that structure? </p>
  
  <ul>
  <li>When I use: <code>allDays=day1+day2</code> my data will be aggregated.</li>
  <li><p>When I use: </p>
  
  <pre><code>allDays=[]
  allDays.append(day1)
  allDays.append(day2)
  </code></pre>
  
  <p>my data will be surrounded by a new array.</p></li>
  </ul>
  
  <p>FYI: I'm using Ubuntu 14.04 and Python: 3.5 (Anaconda)</p>