Re: Python Line Intersection

On 04/10/10 16:24, Mark Tolonen wrote:

"Chris Rebert" <clp2@xxxxxxxxxxxx> wrote in message
news:y2o50697b2c1004091304u627d99bfj44ad56fa76a3cc15@xxxxxxxxxxxxxxxxx
On Fri, Apr 9, 2010 at 11:43 AM, John Nagle <nagle@xxxxxxxxxxx> wrote:
Chris Rebert wrote:
On Fri, Apr 9, 2010 at 8:04 AM, Peyman Askari
<peter_peyman_puk@xxxxxxxx>
wrote:

Hello

This is partly Python related, although it might end up being more
math
related.

I am using PyGTK (GUI builder for Python) and I need to find the
intersection point for two lines. It is easy to do, even if you
only have
the four points describing line segments
(http://www.maths.abdn.ac.uk/~igc/tch/eg1006/notes/node23.html).
However, it
requires that you solve for two equations. How can I do this in
Python,
either solve equations, or calculating intersection points some
other way?

Just solve the equations ahead of time by using generic ones.
<snip>
x = (c - b) / (m-n)

Actually, you don't want to do it that way, because it fails for
vertical
lines, when m and n go to infinity.

As the programmer said upon seeing a stripe-less zebra:
"Oh no, a special case!"

Excellent catch my good sir; although I will point out that strictly
speaking, you can't put vertical lines into slope-intercept form (but
I should not have forgotten that precondition).

And parallel lines, where m and n are equal (divide-by-zero)...

This is actually one place where non-stop arithmetic can be a good thing.

With non-stop arithmetic, when you divide by zero, you get infinity and
everything turns out quite well.
.

Relevant Pages

  • Re: Python Line Intersection
    ... This is partly Python related, although it might end up being more math ... I am using PyGTK (GUI builder for Python) and I need to find the ... or calculating intersection points some other way? ...
    (comp.lang.python)
  • Re: Python Line Intersection
    ... This is partly Python related, although it might end up being more math ... I am using PyGTK (GUI builder for Python) and I need to find the ... or calculating intersection points some other way? ...
    (comp.lang.python)