title: Np.concatenate ValueError: all the input arrays must have same number of dimensions
body: <p>I am trying to concatenate but ended up with the mentioned error. Am also new to python. </p>
  
  <pre><code>def cving(x1, x2, x3, x4, x5, y1, y2, y3, y4, y5, ind1, ind2, ind3, ind4, ind5, num):
  
  if num == 0:
      xwhole = np.concatenate((x2, x3, x4, x5), axis=0)
      yhol = np.concatenate((y2, y3, y4, y5), axis=0)
      return x1, y1, ind1, xwhole, yhol
  elif num == 1:
      xwhole = np.concatenate((x1, x3, x4, x5), axis=0)
      yhol = np.concatenate((y1, y3, y4, y5), axis=0)
      return x2, y2, ind2, xwhole, yhol
  elif num == 2:
      xwhole = np.concatenate((x1, x2, x4, x5), axis=0)
      yhol = np.concatenate((y1, y2, y4, y5), axis=0)
      return x3, y3, ind3, xwhole, yhol
  elif num == 3:
      xwhole = np.concatenate((x1, x2, x3, x5), axis=0)
      yhol = np.concatenate((y1, y2, y3, y5), axis=0)
      return x4, y4, ind4, xwhole, yhol
  else:
      xwhole = np.concatenate((x1, x2, x3, x4), axis=0)
      yhol = np.concatenate((y1, y2, y3, y4), axis=0)
      return x5, y5, ind5, xwhole, yhol
  </code></pre>
  
  <p>Here are some of the output of x1,x2,x3 and x4 *To show some of the output which is used for np.concantate</p>
  
  <pre><code>x1 = [[  1.21537030e+07   5.73132800e+06   1.39127063e-01 ...,   0.00000000e+00
  0.00000000e+00   0.00000000e+00]
  [  2.19181650e+07   6.31495600e+06   1.58992826e-01 ...,   0.00000000e+00
  0.00000000e+00   0.00000000e+00]
  [  9.35311000e+05   5.93920000e+05   1.40974499e-01 ...,   0.00000000e+00
  0.00000000e+00   0.00000000e+00]]
  
  x2= []
  
  x3= []
  
  x4 = [  1.11088300e+06   1.23238400e+06   1.32048109e-01   1.05878525e-01
  9.01409788e-01   1.24716612e+00   7.22766415e-01   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   0.00000000e+00   1.15544472e-01   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   0.00000000e+00
  1.54537898e-02   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   7.82815688e-01
  1.13352981e-04   1.13352981e-04   0.00000000e+00   0.00000000e+00
  8.52792262e-02   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   0.00000000e+00   0.00000000e+00   0.00000000e+00
  0.00000000e+00   6.80117887e-04   0.00000000e+00   0.00000000e+00]
  </code></pre>