title: how to convert the whole DataFrame values into mean values?
body: <p>So I have a list of generator generation in excel:</p>
  <pre><code>Gen1    Gen2    Gen3    Gen4
   12      88      32      13
   22      21      71      11
   22     354      32      74
   43      21      65      11
   33      21      44      11
   55      22      32      43  
   44      21      23      11
   12      21      32      77
   76      33      67      11
   123     55      32      67
   32      21      32      14
   49      76      78      11
   54      21      32      11
   33      21      32      44
   22      44      998     43
   77      21      32      32
   09      34      55      11
   98      21      32      14
   33      21      44      16
   21      23      22     341
  </code></pre>
  <p>There are <code>20 values</code> in each column and I wan to reduce to <code>5 values</code> per column, which will be done by taking the average of <code>4 values</code> at a time. So it will be like taking the average of 1-4 elements first then 5-8, 9-12, 13-16 and last 17-20 elements.
  The expected output will look like this:</p>
  <pre><code>Gen1    Gen2    Gen3    Gen4
  24.75   121      50     27.25
   36      21.25   32.75  35.5
   70      46.25   52.25  25.75 
   46.5    26.75   273.5  32.5
   40.25   24.75   38.25  95.5
  </code></pre>
  <p>I know how to do this in python and my approach is this which gives the exact output that I want:</p>
  <pre><code>import numpy as np
  gen1 = np.array(df['Gen1'])
  gen2 = np.array(df['Gen2'])
  gen3 = np.array(df['Gen3'])
  gen4 = np.array(df['Gen4'])
  
  solutionArr = np.zeros((5,4))
  gen1List = []
  gen2List = []
  gen3List = []
  gen4List = []
  
  for i in range(5):
      gen1List.append(np.mean(gen1[i*4:(i+1)*4]))
      gen2List.append(np.mean(gen2[i*4:(i+1)*4]))
      gen3List.append(np.mean(gen3[i*4:(i+1)*4]))
      gen4List.append(np.mean(gen4[i*4:(i+1)*4]))
  
  solutionArr[:,0] = gen1List
  solutionArr[:,1] = gen2List
  solutionArr[:,2] = gen3List
  solutionArr[:,3] = gen4List
  print(solutionArr)
  </code></pre>
  <p>But I want to use pandas for this because in real dataset I have more 140 Generators with very different names(not like gen1, gen2 etc). So can anyone please help with this?</p>