Python Multiplicative Array Concatenating

Question

If I have a array of an inconsistent size, lists that consists of an (inconsistent) amount of lists:

 lists = [List1, List2, List3,...ListN]

where each contained list is of inconsistent size.

How can I concatenate the contents multiplicatively of each contained array.

Example of target output:

A = ["A","B","C","D"]
B = ["1","2","3","4"]
C = ["D","E","F","G"]
A[0-N] + B[0-N] + C[0-N]

Giving ["A1D","B1D","C1D","D1D",
        "A2D","B2D","C2D","D2D"
        "A3D","B3D","C3D","D3D"
        "A4D","B4D","C4D","D4D"
        "A1E","B1E","C1E","D1E"

         ... "C4G","D4G"  ]

For this specific example it should yield a list length of 4^3. (List length to the power of the number of lists)

However list length is not constant so it is really

List1 Length * List2 Length * List3 Length * ... * ListN Length

For an inconsistent list length:

  A = ["A","B"]
  B = ["1","2","3","4"]

 = ["A1","A2","A3","A4","B1","B2","B3","B4"]

I have tried python maps and zips, but I am having trouble doing for example:

zip(list1, list2, list3)

when:

Amount of lists is not consistent

The lists are not stored separately but collated in one large list,

and the list size is not consistent

Methods described on other SO Question only address consistent size, 2 list, situations. I am having trouble applying these techniques in this situation.

@enderland edited to reflect.

Zano
– Zano

2016-09-20 15:06:30 +00:00
Commented Sep 20, 2016 at 15:06 — Zano
– Zano, Commented Sep 20, 2016 at 15:06

Harun Prasad · Accepted Answer · 2016-09-20 15:21:47Z

1

import itertools
A = ["A","B"]
B = ["1","2","3","4"]
list(itertools.product(A, B))

Generic

lists_var = [List1, List2, List3,...ListN]
list(itertools.product(*lists_var))

answered Sep 20, 2016 at 15:21

Harun Prasad

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Comments

enderland · Accepted Answer · 2016-09-20 15:28:31Z

1

Use itertools to get the results, and then format as you want:

import itertools

A = ["A","B","C","D"]
B = ["1","2","3","4"]
C = ["D","E","F","G"]

lists = [A, B, C]

results = [''.join(t) for t initertools.product(*lists)]

print(results)

prints:

['A1D', 'A1E', 'A1F', 'A1G', 'A2D', 'A2E', 'A2F', 'A2G', 'A3D', 'A3E', 'A3F', 'A3G', 'A4D', 'A4E', 'A4F', 'A4G', 'B1D', 'B1E', 'B1F', 'B1G', 'B2D', 'B2E', 'B2F', 'B2G', 'B3D', 'B3E', 'B3F', 'B3G', 'B4D', 'B4E', 'B4F', 'B4G', 'C1D', 'C1E', 'C1F', 'C1G', 'C2D', 'C2E', 'C2F', 'C2G', 'C3D', 'C3E', 'C3F', 'C3G', 'C4D', 'C4E', 'C4F', 'C4G', 'D1D', 'D1E', 'D1F', 'D1G', 'D2D', 'D2E', 'D2F', 'D2G', 'D3D', 'D3E', 'D3F', 'D3G', 'D4D', 'D4E', 'D4F', 'D4G']

edited Sep 20, 2016 at 15:28

answered Sep 20, 2016 at 15:25

enderland

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1 Comment

SiHa Over a year ago

list() is unneccesary.

SiHa · Accepted Answer · 2016-09-20 15:25:02Z

0

itertools.product Is what you are looking for, I think:

>>> import itertools
>>> A = ["A","B"]
>>> B = ["1","2","3","4"]
>>> C = [A,B]
>>> [''.join(i) for i in itertools.product(*C)]
['A1', 'A2', 'A3', 'A4', 'B1', 'B2', 'B3', 'B4']

edited Sep 20, 2016 at 15:25

answered Sep 20, 2016 at 15:17

SiHa

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2 Comments

enderland Over a year ago

This doesn't handle a list of variable input size.

SiHa Over a year ago

@enderland Good point - d'oh. Fixed. Thanks for pointing that out.

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