title: how i Can create this matrix with 3 for?
body: <p>I want create a matrix for a parameter dem[i][t][c], amount of deman of commodity type c in node i at time t</p>
  
  <p>my Code is :</p>
  
  <pre><code>pdd = 1   # number of node i
  r = 2     # number of commodity type c
  e = 1     # number of period t
  dem = []
  dem1 = []
  dem2 = []
  dem3 = []
  
  for i in range(pdd):
      for c in range(r):    
          for t in range(e):
               dem0 = 1000
               dem1.append (dem0)
          dem2.append (dem1) 
      dem.append(dem2)   
  
  print dem
  </code></pre>
  
  <p>for this expample i want this matrix:  [[[1000],[1000]]]<br>
  but python print this : [[[1000, 1000], [1000, 1000]]]</p>