CODEWITHSUNDEEP
pythonpython-2.x
kezia
kezia

Reputation: 59

Creating dict from all possible combinations of 2 separate lists

I found this useful bit of code among the series of tubes that is the internet:

x=[1,2,3,4]
y=[1,2,3,4]
combos=[(`i`+`n`) for i in x for n in y]
combos
['11','12','13','14','21','22','23','24','31','32','33','34','41','42','43','44']

What I'm trying to do is something like the following:

combinations={(i: `n`+`d`) for i in range(16) for n in x for d in y}
combinations
{1: '11', 2: '12', 3: '13', 4: '14', 5: '21', 6: '22'...etc}

But obviously that's not working. Can this be done? If so, how?

Upvotes: 1

Views: 1205

Answers (4)

ovgolovin
ovgolovin

Reputation: 13410

Also, there is a product function in itertools module that can be used here

from itertools import product
x=[1,2,3,4]
y=[1,2,3,4]

combs = {i+1: ''.join(map(str,p)) for i,p in enumerate(product(x,y))}

''.join(map(str,p)) is the code to convert all the items of p (which is tuple of int-s) into str and then join them using ''.join(...). If you don't need this, just leave p instead of this code.

Also, note, that the syntax {j for j in js} works only from Python 2.7

Upvotes: 1

phihag
phihag

Reputation: 287825

combos = [str(i) + str(n) for i in x for n in y] # or `i`+`n`, () for a generator
combinations = dict((i+1,c) for i,c in enumerate(combos))
# Only in Python 2.6 and newer:
combinations = dict(enumerate(combos, 1))
# Only in Python 2.7 and newer:
combinations = {i+1:c for i,c in enumerate(combos)}

Upvotes: 7

g.d.d.c
g.d.d.c

Reputation: 47988

You ... probably ... don't want that. At least, there's not a great reason to need it that I can see. if what you're after is being able to track their positions you want the result to be a list, which it already is. If you need to know the indexes you should do something like this:

for idx, combo in enumerate(combinations):
  print idx+1, combo

If you actually need them accessible by position (and by list index + 1) you can do something like this:

lookup = dict((idx+1, combo) for idx, combo in enumerate(combinations))

Upvotes: 1

Colin
Colin

Reputation: 10820

Start with your first example:

x=[1,2,3,4]
y=[1,2,3,4]
combos=[(`i`+`n`) for i in x for n in y]

then just add:

combinations = {i: c for i, c in enumerate(combos)}

Upvotes: 1

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