title: Load csv into a specific slice of an numpy array
body: <p>I have bunch of CSV files that contain array data in text format. I need to make a big <code>numpy</code> array out of them. I would prefer not to ingest CSV but that is not in my control.</p>
  
  <p>The way I have been doing this is to use <code>loadtxt()</code> to construct a <code>numpy</code> array from each of these CSV files and then construct the larger array by concatenating these smaller arrays.  This turns out to be the bottle neck.</p>
  
  <p>Ideally I would like an API that takes an array slice and loads the CSV data in place. Are there <code>numpy</code>, <code>scipy</code> or some other module/package that does this, or do I have to roll my own.</p>