Add method clear(); fixes.

Author: gnestlinger

src/Path2D.m

@@ -12,6 +12,7 @@
 % 
 %   Path2D methods (modify path object):
 %   append - Append paths.
+%   clear - Clear path.
 %   derivative - Derivative of path.
 %   frenetOffset - Instantiate PolygonPath from given path and offsets.
 %   restrict - Restrict path domain.
@@ -625,6 +626,11 @@
         %    See also FRENET2CART, POINTPROJECTION.
         [sd,Q,idx,tau] = cart2frenet(obj, xy, phiMax)
 
+        % CLEAR     Clear path.
+        %   OBJ = CLEAR(OBJ) clears all segments from the path so that you
+        %   are left with an empty path.
+        obj = clear(obj)
+        
         % DERIVATIVE    Derivative of path.
         %   OBJD = DERIVATIVE(OBJ,N) returns the Nth derivative OBJD of the
         %   path OBJ w.r.t. the path parameter.

src/PolygonPath.m

@@ -77,7 +77,7 @@
                 obj.ArcLengths = zeros(0,1);
             else
                 obj.ArcLengths = cumsum(hypot(diff(x(:),1,1), diff(y(:),1,1)));
-                end
+            end
 
             if nargin < 5
                 obj = obj.setIsCircuit(1e-5);
@@ -152,6 +152,14 @@
 
         end%fcn
 
+        function obj = clear(obj)
+            obj.x = [];
+            obj.y = [];
+            obj.head = [];
+            obj.curv = [];
+            obj.ArcLengths = [];
+        end%fcn
+        
         function obj = derivative(obj, n)
 
             if nargin < 2
@@ -1158,6 +1166,11 @@ function write2file(obj, fn)
         end%fcn
 
         function obj = xy2Path(x, y)
+            
+            % We cannot estimate heading/curvature from a single waypoint
+            assert(numel(x) ~= 1 && numel(y) ~= 1, ...
+                'XY2PATH:X and Y must not be scalars!')
+            
             [~,g1XY] = gradient([x(:) y(:)]);
             [~,g2XY] = gradient(g1XY);
             gx = g1XY(:,1);

src/SplinePath.m

@@ -75,10 +75,16 @@
 
         function obj = append(obj, obj2)
 
+            if obj.isempty()
+                ds = 0;
+            else
+                [~,P1] = obj.termPoints();
+                dP = obj2.termPoints() - P1;
+                ds = hypot(dP(1), dP(2)) + obj.length();
+            end
+            
             breaks = obj.Breaks;
             coefs = obj.Coefs;
-            arcLen = obj.ArcLengths;
-            [~,P1] = obj.termPoints();
             breaks2 = obj2.Breaks;
             coefs2 = obj2.Coefs;
 
@@ -90,9 +96,7 @@
                 cat(3, zeros(2,n1,k2-k1), coefs), ...
                 cat(3, zeros(2,n2,k1-k2), coefs2));
 
-            dP = obj2.termPoints() - P1;
-            ds = hypot(dP(1), dP(2));
-            obj.ArcLengths = [arcLen; obj2.ArcLengths + arcLen(end) + ds];
+            obj.ArcLengths = [obj.ArcLengths; obj2.ArcLengths + ds];
 
         end%fcn
 
@@ -143,6 +147,13 @@
 
         end%fcn
 
+        function obj = clear(obj)
+            obj.Breaks = 0;
+            obj.Coefs(:,1:end,:) = [];
+            obj.ArcLengths = zeros(0,1);
+            obj.IsCircuit = false;
+        end%fcn
+        
         function obj = derivative(obj, n)
         %DERIVATIVE     Derivative of path.
         %   OBJ = DERIVATIVE(OBJ) returns the derivative of path OBJ.

xUnitTests/SplinePath/AppendTestSpline.m

@@ -1,7 +1,14 @@
 classdef AppendTestSpline < matlab.unittest.TestCase
 
+    properties (TestParameter)
+        PathEmpty = {SplinePath()}
+        PathStraight = {SplinePath.straight([1 2], [5 4])}
+    end
+
+
+
     methods (Test)
-        function testAppend(testCase)
+        function testAppendNonEmpty(testCase)
 
             % Create two "arbitrary" single segment paths with different
             % polynomial degrees
@@ -34,6 +41,24 @@ function testAppend(testCase)
             % The path lengths must match
             verifyEqual(testCase, obj.length(), obj0.length() + obj1.length())
         end%fcn
+
+        function testAppendToEmptyPath(testCase, PathEmpty, PathStraight)
+        % Append non-empty path to empty path.
+
+            obj = PathEmpty.append(PathStraight);
+            verifyEqual(testCase, obj.Breaks, PathStraight.Breaks)
+            verifyEqual(testCase, obj.Coefs(:,:,end-1:end), PathStraight.Coefs)
+            verifyEqual(testCase, obj.cumlengths(), PathStraight.cumlengths())
+        end%fcn
+
+        function testAppendEmptyPath(testCase, PathEmpty, PathStraight)
+        % Append empty path to non-empty path.
+
+            obj = PathStraight.append(PathEmpty);
+            verifyEqual(testCase, obj.Breaks, PathStraight.Breaks)
+            verifyEqual(testCase, obj.Coefs(:,:,end-1:end), PathStraight.Coefs)
+            verifyEqual(testCase, obj.cumlengths(), PathStraight.cumlengths())
+        end%fcn
     end
 
 end%class