Question

I have a pretty simple idea in mind but don’t exactly know how to go about doing it. I have two lists of different length (say 50 in one and 200 in the other).

so

len(x) = 50
len(y) = 200

What I want to do is print out some lines where one value from x corresponds to multiple values of y (does not matter if numbers are repeated).

I.e. suppose x = [1,2,3,4]
y = [7,8,9,10,11,12,13,14,15,16,17]

I want to print out:
1: 7
1: 8
1: 9
1: 10
2: 11
2: 12
2: 13
3: 14
3: 15
3: 16
4: 17

Randomization of values from y does not really matter.
It does not matter how many multiple values get printed out for each value of x. I am basically trying to write a sql script of inserting multiple elements from one table into another and using python to write the script.

I know this can be done by simply iterating over the smallest list and having multiple f.write() statements while incrementing some variable to have multiple values of y associated to a single value of x. But this does not cover all the values of y and looks kind of silly. Is there a better way to go about doing this?

Edit: For the question where how I came up with the association of keys to values, it does not really matter how many values 1 key is associated with (an upper bound of 8 exists). There can be only 1 value or multiple (up to 8). Then again, there can be repetitions of values between keys (i.e. in my example there is not but key 4 can say have values 7/8 also)

Answer 1

Try this Python solution:

>>> x = [1,2,3,4]
>>> y = [7,8,9,10,11,12,13,14,15,16,17]
>>> lnx, lny = len(x), len(y)
>>> groupatleast = (lny + lnx - 1) // lnx
>>> x2y = {}
>>> for i in range(lnx):
    x2y[x[i]] = y[i*groupatleast: (i+1)*groupatleast]


>>> x2y[x[i]] += y[(i+1)*groupatleast:]
>>> for x1,ylist in sorted(x2y.items()):
    for y1 in ylist:
        print ("%i: %i" % (x1, y1))


1: 7
1: 8
1: 9
2: 10
2: 11
2: 12
3: 13
3: 14
3: 15
4: 16
4: 17
>>> 
>>> # Help:
>>> lnx, lny
(4, 11)
>>> groupatleast
3
>>> x2y
{1: [7, 8, 9], 2: [10, 11, 12], 3: [13, 14, 15], 4: [16, 17]}
>>> ylist
[16, 17]
>>>