Add method simplify() for PolygonPath.

Author: gnestlinger

PolygonPath.m

@@ -21,6 +21,7 @@
 %   perpendicularDistance - Distance of path waypoints to line.
 %   rdp - Ramer-Douglas-Peucker point reduction.
 %   rdpIter - Iterative Ramer-Douglas-Peucker line simplification.
+%   simplify - Simplify path.
 %   write2file - Write path to file.
 %   See superclass for more methods.
 % 
@@ -878,6 +879,22 @@
 
         end%fcn
 
+        function obj = simplify(obj)
+        %SIMPLIFY   Simplify path.
+        %   OBJ = SIMPLIFY(OBJ) removes intermediate points from line
+        %   segments of the path OBJ.
+        
+            h = atan2(diff(obj.y), diff(obj.x));
+            dh = [true; diff(h); true];
+            keep = (dh ~= 0);
+
+            obj.x = obj.x(keep);
+            obj.y = obj.y(keep);
+            obj.head = obj.head(keep);
+            obj.curv = obj.curv(keep);
+            obj.ArcLengths = obj.ArcLengths(keep(2:end));
+        end%fcn
+
         function [tau,idx] = s2tau(obj, s)
 
             sObj = obj.arcLengths0();

resources/project/Root.type.Files/xUnitTests.type.File/PolygonPath.type.File/SimplifyTest.m.type.File.xml

@@ -0,0 +1,6 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info>
+    <Category UUID="FileClassCategory">
+        <Label UUID="test" />
+    </Category>
+</Info>

xUnitTests/PolygonPath/SimplifyTest.m

@@ -0,0 +1,38 @@
+classdef SimplifyTest < matlab.unittest.TestCase
+    
+    methods (Test)
+        function testLine(testCase)
+        % Test simplification of a straight path.
+            
+            % Create a line with intermediate points
+            obj0 = PolygonPath.xy2Path(0:10, 0:10);
+            
+            obj1 = obj0.simplify();
+            
+            % The terminal points must match
+            [exp0,exp1] = obj0.termPoints();
+            [act0,act1] = obj1.termPoints();
+            verifyEqual(testCase, act0, exp0);
+            verifyEqual(testCase, act1, exp1);
+            
+            % The length must match
+            verifyEqual(testCase, obj1.length(), obj0.length())
+            
+            % Exactly two points, i.e. one segment, must survive
+            verifyEqual(testCase, obj1.numel(), 1)
+        end%fcn
+        
+        function testNothingToRemove(testCase)
+        % Test path which cannot be simplified.
+        
+            % Create a path where each line segment contains only two
+            % points -> no simplification possible
+            obj0 = PolygonPath.xy2Path(...
+                [0 1 1 2 2 3 3 4 4], ...
+                [0 0 1 1 2 2 3 3 4]);
+            
+            verifyEqual(testCase, obj0, obj0.simplify())
+        end%fcn
+    end
+    
+end%class