title: Calculate percentage of count for a list of arrays
body: <p>Simple problem, but I cannot seem to get it to work. I want to calculate the percentage a number occurs in a list of arrays and output this percentage accordingly.
  I have a list of arrays which looks like this:</p>
  
  <pre><code>import numpy as np
  
  # Create some data   
  listvalues = []
  
  arr1 = np.array([0, 0, 2])
  arr2 = np.array([1, 1, 2, 2])
  arr3 = np.array([0, 2, 2])
  
  listvalues.append(arr1)
  listvalues.append(arr2)
  listvalues.append(arr3)
  
  listvalues
  &gt;[array([0, 0, 2]), array([1, 1, 2, 2]), array([0, 2, 2])]
  </code></pre>
  
  <p>Now I count the occurrences using collections, which returns a a list of collections.Counter:</p>
  
  <pre><code>import collections 
  
  counter = []
  for i in xrange(len(listvalues)):
      counter.append(collections.Counter(listvalues[i]))
  
  counter
  &gt;[Counter({0: 2, 2: 1}), Counter({1: 2, 2: 2}), Counter({0: 1, 2: 2})]
  </code></pre>
  
  <p>The result I am looking for is an array with 3 columns, representing the value 0 to 2 and len(listvalues) of rows. Each cell should be filled with the percentage of that value occurring in the array:</p>
  
  <pre><code># Result
  66.66    0      33.33
  0        50     50
  33.33    0      66.66
  </code></pre>
  
  <p>So 0 occurs 66.66% in array 1, 0% in array 2 and 33.33% in array 3, and so on..</p>
  
  <p>What would be the best way to achieve this?
  Many thanks!</p>