How to combine three lists of different size in order Python

Question

I have three lists: signal, returns, and pct_list:

     signal= ['signal0', 'signal1', 'signal2']

     returns = ['retSCIENCE_MSFT','retLOVE_MSFT','retMUSIC_MSFT',
                 'retSCIENCE_YHOO', 'retLOVE_YHOO', 'retMUSIC_YHOO']

     pct_list = ['Pct_MSFT', 'Pct_YHOO']

I tried using the zip function and it gave me the following result:

    ret_sig_list = list(zip(returns, signal, pct_list))
    ret_sig_list

Output:

     [('retSCIENCE_MSFT', 'signal0', 'Pct_MSFT'),
      ('retLOVE_MSFT', 'signal1', 'Pct_YHOO')]

What I'm trying to get is both MSFT and YHOO lined up with the corresponding signal and percent change like so:

ret_sig_list = [('retSCIENCE_MSFT', 'signal0', 'Pct_MSFT'),
               ('retLOVE_MSFT', 'signal1', 'Pct_MSFT'),
               ('retMUSIC_MSFT', 'signal2', 'Pct_MSFT'),
               ('retSCIENCE_YHOO', 'signal0', 'Pct_YHOO'),
               ('retLOVE_YHOO', 'signal1', 'Pct_YHOO'),
               ('retMUSIC_YHOO','signal2', 'Pct_YHOO')]

I tried with list(zip(returns, signal, pct_list)), but it seems to default down to the lowest number of elements in the three lists, which is pct_list.

If anyone knows how I can tackle this problem, I'd be very greatful! I'd like to use the ret_sig_list with a for-loop to perform a calculation on multiple stocks percent change goes up or down to give returns based on the associated words; science, love, music, etc. I got the words from a Python package for Google Trends called Pytrends which I'd recommend, it's very cool!

Answer 1

Use itertools.cycle :

In [2]: from itertools import cycle

In [3]: list(zip(returns, cycle(signal), cycle(pct_list)))
Out[3]:
[('retSCIENCE_MSFT', 'signal0', 'Pct_MSFT'),
 ('retLOVE_MSFT', 'signal1', 'Pct_YHOO'),
 ('retMUSIC_MSFT', 'signal2', 'Pct_MSFT'),
 ('retSCIENCE_YHOO', 'signal0', 'Pct_YHOO'),
 ('retLOVE_YHOO', 'signal1', 'Pct_MSFT'),
 ('retMUSIC_YHOO', 'signal2', 'Pct_YHOO')]

Answer 2

So I managed to almost find a solution, it's not ideal, but close. I say not ideal cause not including the specific words from the list of ["SCIENCE", "LOVE", "MUSIC"] but it's the only way to create an ordered zip list.

  stock_list = ['MSFT', 'YHOO'] 
  stock_list_v2 = []

     for stock in stock_list:
          for i in range(10):
           s = 'ret' + str(i) + '_' + stock

           stock_list_v2.append(s)    
  stock_list_v2   

Output:

  ['ret0_MSFT',
  'ret1_MSFT',
  'ret2_MSFT',
  'ret3_MSFT',
  'ret4_MSFT',
  'ret5_MSFT',
  'ret6_MSFT',
  'ret7_MSFT',
  'ret8_MSFT',
  'ret9_MSFT',
  'ret0_YHOO',
  'ret1_YHOO',
  'ret2_YHOO',
  'ret3_YHOO',
  'ret4_YHOO',
  'ret5_YHOO',
  'ret6_YHOO',
  'ret7_YHOO',
  'ret8_YHOO',
  'ret9_YHOO']

Next signals:

  sig = list(range(10))
  sig
  signal = ["signal{}".format(*sig) for sig in enumerate(sig)]
  signal

Output:

  ['signal0',
   'signal1',
   'signal2',
   'signal3',
   'signal4',
   'signal5',
   'signal6',
   'signal7',
   'signal8',
   'signal9']

Next, pct.

   stock_list = ['MSFT', 'YHOO'] 
   stock_list_v3 = []

   for stock in stock_list:
         for i in range(10):

         p = 'pct' + str(i) + '_' + stock
        stock_list_v3.append(p)
  stock_list_v3

Output:

   ['pct0_MSFT',
    'pct1_MSFT',
    'pct2_MSFT',
    'pct3_MSFT',
    'pct4_MSFT',
    'pct5_MSFT',
    'pct6_MSFT',
    'pct7_MSFT',
    'pct8_MSFT',
    'pct9_MSFT',
    'pct0_YHOO',
    'pct1_YHOO',
    'pct2_YHOO',
    'pct3_YHOO',
    'pct4_YHOO',
    'pct5_YHOO',
    'pct6_YHOO',
    'pct7_YHOO',
    'pct8_YHOO',
    'pct9_YHOO']

Now we import cycle from itertools like so.

     from itertools import cycle

     full_list = list(zip(stock_list_v2, cycle(signal), stock_list_v3))

     full_list

Output:

     [('ret0_MSFT', 'signal0', 'pct0_MSFT'),
      ('ret1_MSFT', 'signal1', 'pct1_MSFT'),
      ('ret2_MSFT', 'signal2', 'pct2_MSFT'),
      ('ret3_MSFT', 'signal3', 'pct3_MSFT'),
      ('ret4_MSFT', 'signal4', 'pct4_MSFT'),
      ('ret5_MSFT', 'signal5', 'pct5_MSFT'),
      ('ret6_MSFT', 'signal6', 'pct6_MSFT'),
      ('ret7_MSFT', 'signal7', 'pct7_MSFT'),
      ('ret8_MSFT', 'signal8', 'pct8_MSFT'),
      ('ret9_MSFT', 'signal9', 'pct9_MSFT'),
      ('ret0_YHOO', 'signal0', 'pct0_YHOO'),
      ('ret1_YHOO', 'signal1', 'pct1_YHOO'),
      ('ret2_YHOO', 'signal2', 'pct2_YHOO'),
      ('ret3_YHOO', 'signal3', 'pct3_YHOO'),
      ('ret4_YHOO', 'signal4', 'pct4_YHOO'),
      ('ret5_YHOO', 'signal5', 'pct5_YHOO'),
      ('ret6_YHOO', 'signal6', 'pct6_YHOO'),
      ('ret7_YHOO', 'signal7', 'pct7_YHOO'),
      ('ret8_YHOO', 'signal8', 'pct8_YHOO'),
      ('ret9_YHOO', 'signal9', 'pct9_YHOO')]

Hope that helps anyone who was curious about how to solve it :) Thanks again to PrestonM for suggesting an algo, and Juapana for helping suggest using itertools cycle.