title: How to pass a list of lists through a for loop in Python?
body: <p>I have a list of lists :</p>
  
  <pre><code>sample = [['TTTT', 'CCCZ'], ['ATTA', 'CZZC']]
  count = [[4,3],[4,2]]
  correctionfactor  = [[1.33, 1.5],[1.33,2]]
  </code></pre>
  
  <p>I calculate frequency of each character (pi), square it and then sum (and then I calculate het = 1 - sum). </p>
  
  <pre><code>The desired output [[1,2],[1,2]] #NOTE: This is NOT the real values of expected output. I just need the real values to be in this format. 
  </code></pre>
  
  <p>The problem: I do not how to pass the list of lists(sample, count) in this loop to extract the values needed. I previously passed only a list (eg <code>['TACT','TTTT'..]</code>) using this code. </p>
  
  <ul>
  <li>I suspect that I need to add a larger for loop, that indexes over each element in sample (i.e. indexes over <code>sample[0] = ['TTTT', 'CCCZ']</code> and <code>sample[1] = ['ATTA', 'CZZC']</code>. I am not sure how to incorporate that into the code.</li>
  </ul>
  
  <p>**
  Code</p>
  
  <pre><code>list_of_hets = []
  for idx, element in enumerate(sample):
      count_dict = {}
      square_dict = {}
      for base in list(element):
           if base in count_dict:
              count_dict[base] += 1
          else:
              count_dict[base] = 1
      for allele in count_dict: #Calculate frequency of every character
          square_freq = (count_dict[allele] / count[idx])**2 #Square the frequencies
          square_dict[allele] = square_freq        
      pf = 0.0
      for i in square_dict:
          pf += square_dict[i]   # pf --&gt; pi^2 + pj^2...pn^2 #Sum the frequencies
      het = 1-pf                    
      list_of_hets.append(het)
  print list_of_hets
  
  "Failed" OUTPUT:
  line 70, in &lt;module&gt;
  square_freq = (count_dict[allele] / count[idx])**2
  TypeError: unsupported operand type(s) for /: 'int' and 'list'er
  </code></pre>