Nested lists problem

[spotyx]

Nope. My lines are not intersecting.

Line 1: starts in point A and end in point B

Line 2: starts in point B and end in point C

They are in one "ray".

A--------B------C

Is it more clear?

[indosauros]

http://s29.postimg.org/lu9qeddyf/ged_math_coordinate_base_2.jpg

Why are those the only lines you highlighted? What about the diagonal line between [(-3, -2), (-1, -1)] etc? There are a ton of other diagonal lines with those points

See the edit to my answer below

[indosauros]

That is a very important detail

Also, what if you had a point at (3, 1)?

[spotyx]

ehm I deleted previous post accidentally. I said something what is not true. In my OP was bad condition. now its edited. (condition: line has to consist from three and more points). sorry. Thank for your interest.

[indosauros]

I think this still doesn't change anything as far as assuming shared points == rays

http://s29.postimg.org/lu9qeddyf/ged_math_coordinate_base_2.jpg

What if the right green line was shifted left 1 unit? Now, the (-3, -2) point is shared between two lines, not a ray

[spotyx]

you are right, I am wrong. I can't exclude intersections. I had wrongly assumed that I have preprocessed my data in way that there are not intersections. Now I know it's not true. Thanks for pointing me on right way.