CODEWITHSUNDEEP
pythonarraysiteration
andresf
andresf

Reputation: 198

Iterate over N arrays in a certain order

I want to iterate over n arrays in a certain way. The number of arrays is undefined.

This would be an example:

this entry:

[['A', 'B', 'C'], ['D', 'E'], ['F', 'G']]

This output should be printed:

[ADF, ADG, AEF, AEG, BDF, BDG, BEF, BEG, CDF, CDG, CEF, CEG]

To be more specific with the way to order them:

ADF - ADG - AEF - AEG - BDF - BDG - BEF - BEG - CDF - CDG - CEF - CEG
111   112   121   122   211   212   221   222   311   312   321   322

Where the numbers are the index of each letter in the previous arrays.

another example:

Input:

[['A', 'B', 'C'], ['D', 'E'], ['F', 'G', 'H']]

Output:

ADF - ADG - ADH - AEF - AEG - AEH - BDF - BDG - BDH - BEF - BEG - BEH - CDF - CDG - CDH - CEF - CEG - CEH 
111   112   113   121   122   123   211   212   213   221   222   223   311   312   313   321   322   323

Is there a way to make a recursive function to obtain that order? I tried to find a pattern with the length of each array, but I could not find this solution. I'm trying to do it in python

Upvotes: 0

Views: 45

Answers (1)

B. M.
B. M.

Reputation: 18668

it is just a product :

from itertools import product
[''.join(x) for x in product(['A', 'B', 'C'], ['D', 'E'], ['F', 'G'])]
# ['ADF', 'ADG', 'AEF', 'AEG', 'BDF', 'BDG', 'BEF', 'BEG', 'CDF', 'CDG', 'CEF', 'CEG']

The recursive way:

def prod (sets):
    if not sets : return ['']
    res=[]
    for x in sets[0]:
        for y in prod(sets[1:]):
            res.append (x+y)
    return res

Upvotes: 2

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