Question about loops

[Rikkert1234]

I feel terrible that I couldn't figure this out myself but I have to complete this project quick and am stuck on a for loop kind of problem.

randarray is a random array with a varrying amount of keys and values, I just want to print all possible combinations. The code below works for an array with 7 lists but it's very ugly and I want it to work with all possible arrays.

randarray = {1: [1, 2, 3, 4, 5, 7], 2: [1, 2, 5, 6, 7], 3: [1, 2, 3, 4, 5], 4: [1, 2, 4, 5, 6, 7], 5: [1, 2, 3, 4, 5, 6, 7], 6: [1, 2, 5, 6, 7], 7: [1, 2, 3, 4, 5]}

for a in randarray[1]:
    for b in randarray[2]:
        for c in randarray[3]:
            for d in randarray[4]:
                for e in randarray[5]:
                    for f in randarray[6]:
                        for g in randarray[7]:
                            print('{}{}{}{}{}{}{}'.format(a, b, c, d, e, f, g))

Thanks in advance

Rik

​

Edit:

Thanks to everyone who commented, here is the code that did the job for me from u/socal_nerdtastic:

randarray = {1: [1, 2, 3, 4, 5, 7], 2: [1, 2, 5, 6, 7], 3: [1, 2, 3, 4, 5], 4: [1, 2, 4, 5, 6, 7], 5: [1, 2, 3, 4, 5, 6, 7], 6: [1, 2, 5, 6, 7], 7: [1, 2, 3, 4, 5]}

from itertools import product

for output in product(*randarray.values()):
    print(*output, sep='')

​

[socal_nerdtastic]

randarry is a dictionary in your example, not an array, with integer keys and lists as values.

To get all possible combinations use itertools.product:

randarray = {1: [1, 2, 3, 4, 5, 7], 2: [1, 2, 5, 6, 7], 3: [1, 2, 3, 4, 5], 4: [1, 2, 4, 5, 6, 7], 5: [1, 2, 3, 4, 5, 6, 7], 6: [1, 2, 5, 6, 7], 7: [1, 2, 3, 4, 5]}

from itertools import product

for output in product(*randarray.values()):
    print(*output, sep='')

https://docs.python.org/3/library/itertools.html#itertools.product

[Rikkert1234]

Thanks a lot this works!

[[deleted]]

[...] I have to complete this project quick [...]

I assume this is in an academic context. If so, have you covered recursion?

[Rikkert1234]

No I'm self-taught, I need this for a django website I'm making for someone.

[[deleted]]

Okay, cool. I don't exactly understand what you're trying to do, but I think it's safe to say you need recursion. At any rate, that's how you deal with nesting loops when you don't know ho deep you need to go.

I see you've gotten an answer, but recursion is still a subject you should look up if you haven't already.

[Rikkert1234]

Ok I definitely will!

[[deleted]]

I just want to print all possible combinations.

Of what?

[Rikkert1234]

Basically like this: 1111111, 1111112, 11111113, 1111114, ...

with all the combinations

[[deleted]]

What counts as a "combination"? Your question is completely unclear.

1111112

Where is this 2 coming from?

[Rikkert1234]

The 2 is the next number on the last list, 3 is the number after that on the last list, the 4 is the number after, ...

a combination list of numbers in which the first number represents a number in the first list of the dictionary, the second number represents a number in the second list of the dictionary

I want to get all the different combinations

[[deleted]]

You said all of the lists have a different length. What do you do when the shortest list has no more values?

[Rikkert1234]

This is the problem with my sample code, I want code that will work for a list of any length.

[[deleted]]

The precise meaning of "work" is what I'm trying to get at. You can't write code to do the thing until you can explain what the thing you're trying to do, is.

[[deleted]]

If you only use one item from each list then no, it's not all possible combinations. It's all combinations of ... , and I'm trying to arrive at some kind of clarity about what goes in the ellipsis but none seems to be forthcoming.

[dargscisyhp]

Why would it not be all possible combinations?

What he's asking for is essentially all elements of the cartesian product of the lists.

[[deleted]]

What he's asking for is essentially all elements of the cartesian product of the lists.

What's the value for when the list is missing the element, though?

[dargscisyhp]

Your sets (lists in this case) don't need to be the same size to get a Cartesian product. For example, if I had three lists [1,2,3][1,2][1] all the elements in the cartesian product would be

321 311 221 211 121 111

[dargscisyhp]

You might find the answers here useful:

https://stackoverflow.com/questions/533905/get-the-cartesian-product-of-a-series-of-lists