title: Append column of matrix to different dictionary element
body: <p>Following the previous comment I am including only the code necessary to understand the issue. I hope it is understandable. Here is the code:</p>
  <pre><code>list_dict = [[] for i in range(10)]
  out_dict_2 = {}
  out_dict_2.update({'key_a': list_dict, 'key_b': list_dict, 'key_c': list_dict})
  
  for index in range(10):
      for line in list_2:
          line = line.strip()
          line = line.split()
          if areallnumbers(line): # check whether all the elements in the list are float
              out_dict_2['key_a'][index].append(line[0])
              out_dict_2['key_b'][index].append(line[1])
              out_dict_2['key_c'][index].append(line[2])
  </code></pre>
  <p>where list_2 looks like <strong>EDIT:(I can have also more list of the same type, in my case they are 10--&gt; <code>for index in range(10):</code>):</strong></p>
  <pre><code>['5.00', '-4601.24', '31.73']
  ['11.04', '-4517.66', '32.51']
  ['17.08', '-4418.59', '33.24']
  ['23.12', '-4305.34', '33.93']
  ['29.17', '-4179.09', '34.59']
  ......
  </code></pre>
  <p><strong>I am trying to have the first column of each list appended to one dictionary element, i.e. the first column to out_dict_2[key_a][index] and so on, so each value is a list of 10 lists. Something like this (assuming the 10 lists are all equal to the example list I have given:</strong></p>
  <pre><code>key_a [['5.00'    , '11.04'   , '17.08'   , '23.12'   , ...],...,['5.00'    , '11.04'   , '17.08'   , '23.12'   , ...]]
  key_b [['-4601.24', '-4517.66', '-4418.59', '-4418.59', ...],...,['5.00'    , '11.04'   , '17.08'   , '23.12'   , ...]]
  key_c [['31.73'   , '32.51'   , '33.24'   , '33.93'   , ...],...,['5.00'    , '11.04'   , '17.08'   , '23.12'   , ...]]
  </code></pre>
  <p>What I am actually getting is:</p>
  <pre><code>key_a [['5.00', '-4601.24', '31.73'...]['5.00', '-4601.24', '31.73'...]...['5.00', '-4601.24', '31.73'...]
  key_b [['5.00', '-4601.24', '31.73'...]['5.00', '-4601.24', '31.73'...]...['5.00', '-4601.24', '31.73'...]
  key_c [['5.00', '-4601.24', '31.73'...]['5.00', '-4601.24', '31.73'...]...['5.00', '-4601.24', '31.73'...]
  </code></pre>
  <p>as if each line is appended to each dictionary key, why?</p>