PYTHON CLASSES FOR POINTS AND LINES TO CALCULATE THE AREA

ENCLOSED BY LINES.

©Mubeen Shahid

Given:

a list containing point objects where I have point object and line object defined as:

class Point(): def __init__(self, x, y): self._x = x self._y = y def __eq__(self, other): return self.__dict__ == other.__dict__

and

class Line(object): def __init__(self,p1, p2,name): self.p1=p1 self.p2=p2 self.name=name

Problem:

I am trying to create a list of points, in the same order in which the lines are connected;

upto now I can detect connections between lines e.g.

p1=Point(2.1,2.0) p2=Point(1.1,5.0) p3=Point(4.1,3.0) p4=Point(3.1,2.0)

and

line1=Line(p1,p2,"line.1") line2=Line(p3,p2,"line.2") line3=Line(p3,p4,"line.3") line4=Line(p4,p1,"line.4")

-

Normally, the points are not listed in order, and similarly the lines are also not ordered.

Upto now I can detect the spline connections in the following format (list of lists

containing tuples:

connectionList= [ [(line1, line1.p1), (line4, line4.p2)] [(line2, line2.p1), (line3, line3.p1)] [(line3, line3.p2), (line4, line4.p1)] ... ] I am trying to achieve the result in format [p1, p3,p4, ..]

EDIT:

The solution to above problem (after using the answer from @marqs) embedded in an

example, is below:

class Point(): def __init__(self, x, y):

self._x = x self._y = y def __eq__(self, other): return self.__dict__ == other.__dict__ class Line(object): def __init__(self,p1, p2,name): self.p1=p1 self.p2=p2 self.name=name p1=Point(1,1) p2=Point(5,2) p3=Point(1,5) p4=Point(2,2) p5=Point(5,5) p6=Point(6,1) p7=Point(6,5) p8=Point(2,5) s1=Line(p1,p3,"Line1") s2=Line(p7,p6,"Line2") s3=Line(p1,p6,"Line3") s4=Line(p2,p5,"Line4") s5=Line(p4,p8,"Line5") s6=Line(p4,p2,"Line6") s7=Line(p5,p7,"Line7") s8=Line(p3,p8,"Line8") def connectivity(s,sl): s_L=[] s_L=[spl1 for spl1 in sl] s_L.remove(s) connection=[] for sp in s_L: if s.p1==sp.p1: connection.append([(s, s.p1), (sp, sp.p1)]) continue elif s.p1==sp.p2: connection.append([(s, s.p1), (sp, sp.p2)]) continue elif s.p2==sp.p1: connection.append([(s, s.p2), (sp, sp.p1)]) continue elif s.p2==sp.p2: connection.append([(s, s.p2), (sp, sp.p2)]) continue else:

pass return connection def getPoints(connectionList): firstConnection = connectionList[0] points = [firstConnection[1][1]] lastLine = firstConnection[1][0] connectionList.remove(firstConnection) while len(connectionList): for connection in list(connectionList): (line1, p1), (line2, p2) = connection if lastLine == line1 or lastLine == line2: points.append(p1) lastLine = line1 if lastLine == line2 else line2 connectionList.remove(connection) break return points con=[] complete=[] slist=[s1,s2,s3,s4,s5,s6,s7,s8] for splineX in slist: con=connectivity(splineX, slist) prev=[temp1 for temp01 in complete for temp1 in temp01] if not (con[0][0] in prev or con[0][1] in prev): complete.append(con[0]) if len(con)>1: if not (con[1][0] in prev or con[1][1] in prev): complete.append(con[1]) connectionList=[xyz for xyz in complete] pointList=getPoints(connectionList) pointcord=[] for pnt in pointList: pointcord.append((pnt._x, pnt._y)) print "Ordered list of points:\n" , pointcord

The result is:

Ordered list of points: [(1, 1), (6, 1), (6, 5), (5, 5), (5, 2), (2, 2), (2, 5), (1, 5)]