Adapting python's itertools.product inside for in c#

Question

There is python code that will fill a list given a k number

k=4
myList = {}
for objectOfInterest in [''.join(item) for item in product('01', repeat=k)]:
    if objectOfInterest[:-1] in myList:
        myList[objectOfInterest[:-1]].append(objectOfInterest[1:])
    else:
        myList[objectOfInterest[:-1]] = [objectOfInterest[1:]]

Resulting on:

k=3
{'11': ['10', '11'], '10': ['00', '01'], '00': ['00', '01'], '01': ['10', '11']}

k=4
    {'010': ['100', '101'], '011': ['110', '111'], '001': ['010', '011'], '000': ['000', '001'], '111': ['110', '111'], '110': ['100', '101'], '100': ['000', '001'], '101': ['010', '011']}


when k=5
{'0110': ['1100', '1101'], '0111': ['1110', '1111'], '0000': ['0000', '0001'], '0001': ['0010', '0011'], '0011': ['0110', '0111'], '0010': ['0100', '0101'], '0101': ['1010', '1011'], '0100': ['1000', '1001'], '1111': ['1110', '1111'], '1110': ['1100', '1101'], '1100': ['1000', '1001'], '1101': ['1010', '1011'], '1010': ['0100', '0101'], '1011': ['0110', '0111'], '1001': ['0010', '0011'], '1000': ['0000', '0001']}

I would like to translate it to c# code What would be the best way, I was thinking LINQ could help...

int k =4;
string myList ="";

How would loop

objectOfInterest in [''.join(item) for item in product('01', repeat=k)]:

look like in c#? Is it a foraech item in objectOfInterest... knowing the fact an stackoverflow answer suggests:

public static List< Tuple<T, T> > Product<T>(List<T> a, List<T> b)
    where T : struct
{
    List<Tuple<T, T>> result = new List<Tuple<T, T>>();

    foreach(T t1 in a)
    {
        foreach(T t2 in b)
            result.Add(Tuple.Create<T, T>(t1, t2));
    }

    return result;
}

n.b. struct here means that T must be a value type or a structure. Change it to class if you need to throw in objects such as Lists, but be aware of potential referencing issues.

Then as a driver:

List<int> listA = new List<int>() { 1, 2, 3 };
List<int> listB = new List<int>() { 7, 8, 9 };

List<Tuple<int, int>> product = Product<int>(listA, listB);
foreach (Tuple<int, int> tuple in product)
    Console.WriteLine(tuple.Item1 + ", " + tuple.Item2);

Output:

1, 7
1, 8
1, 9
2, 7
2, 8
2, 9
3, 7
3, 8
3, 9

I think the _first_ step would be to duplicate the functionality of [`itertools.product`](http://docs.python.org/2/library/itertools.html#itertools.product). — , Dec 13 '13 at 18:00
there is an answer suggestin `public static List< Tuple > Product(List a, List b) where T : struct { List> result = new List>(); foreach(T t1 in a) { foreach(T t2 in b) result.Add(Tuple.Create(t1, t2)); } return result; }`... — edgarmtze, Dec 13 '13 at 18:02
and then `List listA = new List() { 1, 2, 3 }; List listB = new List() { 7, 8, 9 }; List> product = Product(listA, listB); foreach (Tuple tuple in product) Console.WriteLine(tuple.Item1 + ", " + tuple.Item2);` — edgarmtze, Dec 13 '13 at 18:03
Your latest example can actually be done a little more cleanly with a linq `Zip` extension, but I am not sure how it relates to your original question. — crthompson, Dec 13 '13 at 18:19
In fact I would like to use python's itertools.product functionality in the for loop `for objectOfInterest in [''.join(item) for item in product('01', repeat=k)]: if objectOfInterest[:-1] in myList: myList[objectOfInterest[:-1]].append(objectOfInterest[1:]) else: myList[objectOfInterest[:-1]] = [objectOfInterest[1:]]` but do not know how to adapt it — edgarmtze, Dec 13 '13 at 18:35

Arithmomaniac · Accepted Answer · 2014-03-27T00:47:26.327

I recently wrote a class that effectively emulates itertools.product, prompted by a Microsoft interview question. You can grab it here. It doesn't currently support repeat, but you can emulate that.

Pulling things together:

//emulate the repeat step. http://stackoverflow.com/q/17865166/1180926
List<List<char>> zeroOneRepeated = Enumerable.Range(0, k)
    .Select(i => '01'.ToList())
    .ToList(); 

//get the product and turn into strings
objectsOfInterest = CrossProductFunctions.CrossProduct(zeroOneRepeated)
    .Select(item => new string(item.ToArray()));

//create the dictionary. http://stackoverflow.com/a/938104/1180926
myDict = objectsOfInterest.GroupBy(str => str.Substring(0, str.Length - 1))
    .ToDictionary(
        grp => grp.Key, 
        grp => grp.Select(str => str.Substring(1)).ToList()
    );

Adapting python's itertools.product inside for in c#

1 Answers1