Understand list comprehension and draw

[bowlofred]

my_example = [(x,v,w) for x in list(range(6)) for y in list(range(7)) for z in list(range(8))]

Here, I have three different ranges (6, 7 and 8). If I use itertools, I can use only one, no ?

True, but it's pretty simple to trim out what you don't need. For instance, if I generate all combinations of 0-4 with 3 digits in increasing order:

Output:
>>> list(combinations(range(5), 3))
[(0, 1, 2), (0, 1, 3), (0, 1, 4), (0, 2, 3), (0, 2, 4), (0, 3, 4), (1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]

But I don't want any where the middle digit is 2.

Output:
>>> [ x for x in combinations(range(5), 3) if x[1] != 2]
[(0, 1, 2), (0, 1, 3), (0, 1, 4), (0, 3, 4), (1, 3, 4), (2, 3, 4)]

With this code, for example, I have as result :

Output:
[(0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (1, 0, 0) [...]

I don't understand. What code does that? The my_example code you have above doesn't run, but if you change the (x,v,w) to (x,y,z), then it prints out something that looks reasonable.

Output:
>>> [(x,y,z) for x in range(6) for y in range(7) for z in range(8)]
[(0, 0, 0), (0, 0, 1), (0, 0, 2), (0, 0, 3), (0, 0, 4), (0, 0, 5), (0, 0, 6), (0, 0, 7), (0, 1, 0), (0, 1, 1), (0, 1, 2), (0, 1, 3), (0, 1, 4), (0, 1, 5), (0, 1, 6), (0, 1, 7), (0, 2, 0), (0, 2, 1), (0, 2, 2), (0, 2, 3), (0, 2, 4), (0, 2, 5) ...
 (5, 5, 0), (5, 5, 1), (5, 5, 2), (5, 5, 3), (5, 5, 4), (5, 5, 5), (5, 5, 6), (5, 5, 7), (5, 6, 0), (5, 6, 1), (5, 6, 2), (5, 6, 3), (5, 6, 4), (5, 6, 5), (5, 6, 6), (5, 6, 7)]

My wish is to know :
1/ how can I generate only one time (0,0,0) with no repetition ?

It looks like you've done that above with your my_example code. Can you run it and see how you want it to be different?

2/ in the same way, how can I generate them with only three different digits (ie (1,2,3)) ?

I think you need to be more explicit. combinations() will give you sets without repetition. Can you give an example list and detail how it differs from something like combinations(range(8), 3)?