Okay I'll try. What the main job is to do an algorithm which simples a line. Algorithm deletes points which are unnecessary accurate according to tolerance distance user gives.
>> I started by converting the pseudocode I had to python. Pseudocode: http://web.cs.sunyit.edu/~poissad/projects/Curve/about_algorithms/lang 1. function lang(PointList[], Tolerance) 2. key=0 3. endP= PointList.length-1 4. do { 5. endP= PointList.length-1 6. if (key+1 != endP) // If there are intermediate points 7. line= new Line( PointList[key], PointList[endP]) 8. /* Find the point with the furthest perpendicular distance */ 9. maxIndex= key+1 10. maxD= perpendicularDistance(line, PointList[maxIndex]) 11. for (i=maxIndex+1; i<endP; i++) 12. d= perpendicularDistance(line, PointList[i]) 13. if (d > maxD) 14. maxIndex=i 15. maxD=d 16. if (maxD > Tolerance) 17. endP--; 18. else 19. for (i=key+1; i<endP; i++) 20. PointList.remove(i) 21. key= endP 22. } while ( endP != PointList.length-1 ) 23. end >> Still I have problems with perpendicular distance and creating a line >> with python. What I mean by creating a line is what Alan answered "checking distances/intersections etc only requires the math model." I need the mathematical model not a picture/graph. I'll try move forward with Bens suggestion of ‘math’ module which probably help me with both mathematical line model between two points and its distance between the intermediate points. > <URL:http://docs.python.org/3/library/math.html#trigonometric-functions>. Here is a picture of the lang algorithm, where you can see distance of interest by purple http://psimpl.sourceforge.net/lang.html. I'll ask later if I can't get this work. Cheers! 2014-04-15 3:23 GMT+03:00 Ben Finney <ben+pyt...@benfinney.id.au>: > Laura Kauria <lacat...@gmail.com> writes: > > > Thanks a lot for all the help! I got the courage to start at least.. > > Congratulations! Courage is a necessary ingredient when starting :-) > > Could you please avoid top-posting, and instead use interleaved style > <URL:https://en.wikipedia.org/wiki/Posting_style#Interleaved_style> for > your replies, so the conversation is in a natural order. > > > I started by converting the pseudocode I had to python. > > If it's short and simple, please post it here so we can discuss it in > context. > > > Still I have problems with perpendicular distance and creating a line > > with python. > > I need to create a line between two points and then check what is the > > distance between a line and intermediate points which were between lines > > start and end point. If someone could help me with this? I could not > > understand can I do this without math library or not? > > The ‘math’ module in the standard library has trigonometric functions > <URL:http://docs.python.org/3/library/math.html#trigonometric-functions>. > If you have co-ordinate data and know how to use trigonometry, then > those functions will do what you expect. > > -- > \ “If I melt dry ice, can I swim without getting wet?” —Steven | > `\ Wright | > _o__) | > Ben Finney > > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor >
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