How to output set items without the curly braces ?

[jimthecanadian]

Hi all,

I have not coded for a while and am still getting used to all the new fangled data types :)

I am taking a course in Database mining and we have been set a first problem of mining frequent patterns using the apriori algorithm. Now I have a pretty solid understanding of the logic but I when I am trying to print because of the way I have my data represented I can't figure out how to do it the way I would like. I am able to get through the first pass where I end up with a list of 1 item sets and a related value in another list. so the data looks like this candidates({book},{pencil}, {School bag},...) and I am able to iterate through it quite simply by doing this:

for x in candidates:
    for y in x:
        print(y ))

I do this because I do not wan the curly braces printed do I dereference he set element. Now on the second pass I have a list of sets containing two elements candidates({book, pencil},{book, school bag}, {pencil, School bag},...) and I would like to print it the same way with both set elements on one line. I have tried this but, no luck

for x in candidates:
    for y,z in x:
        print(y + " , " + z))

Thanks for any pointers

[Yoriz]

candidates = ({'book'}, {'pencil'}, {'School bag'})

for x in candidates:
    print(', '.join(y for y in x))

Output:
book
pencil
School bag

candidates2 = ({'book', 'pencil'}, {'book', 'school bag'},
               {'pencil', 'School bag'})

for x in candidates2:
    print(', '.join(y for y in x))

Output:
pencil, book
book, school bag
pencil, School bag

[jimthecanadian]

Thanks, Yoriz. exactly what I needed

[perfringo]

There is also possibility to use unpacking, which can be used with any iterable (note that sets are unordered):

>>> first = ({'book'}, {'pencil'}, {'School bag'})
>>> for element in first:
...     print(*element)
...
book
pencil
School bag
>>> second = ({'book', 'pencil'}, {'book', 'school bag'}, {'pencil', 'School bag'})
>>> for element in second:
...     print(*element, sep=', ')
... 
pencil, book
book, school bag
School bag, pencil