title: Loop over lists and concat in pd.dataframe
body: <p>I'm trying to mulitply a DataFrame with a numpy array as follows:</p>
  
  <pre><code>import numpy as np
  from pandas import*
  import pandas as pd
  
  C = np.arange(30).reshape(5, 6)
  
  df = pd.DataFrame(np.arange(48).reshape((8, 6)), columns=list('abcdef'))
  pxc = df / df.shift(1) - 1
  
  def concatArrays(A, B):
       cArrays_0 = np.sum(A[0,]*B, axis=1)
       cArrays_1 = np.sum(A[1,]*B, axis=1)
       cArrays_2 = np.sum(A[2,]*B, axis=1)
       cArrays_3 = np.sum(A[3,]*B, axis=1)
       cArrays_4 = np.sum(A[4,]*B, axis=1)
       #(...)
  
       pieces = [cArrays_0, cArrays_1, cArrays_2, cArrays_3, cArrays_4] #(...)
       concatenated = concat(pieces, axis=1, join='outer')
       return concatenated
  
  print concatArrays(C, pxc) 
  </code></pre>
  
  <p>I would like to create a loop so that 'concatenated is automatic regardless of the number of lists in C, avoiding writing each cArray_i by hand.</p>
  
  <p>Thanx</p>