# d3/d3

Fix polygon.centroid for open polygons.

```The implementation assumed closed polygons, but it should work on either. This
is a partial fix for #443.```
1 parent f67e895 commit 85ad3c16b031f2e21969123fbf3749f796623226 mbostock committed Jan 29, 2012
Showing with 51 additions and 25 deletions.
1. +4 −4 d3.geom.js
2. +1 −1 d3.geom.min.js
3. +4 −4 src/geom/polygon.js
4. +42 −16 test/geom/polygon-test.js
8 d3.geom.js
 @@ -192,16 +192,16 @@ d3.geom.polygon = function(coordinates) { coordinates.centroid = function(k) { var i = -1, - n = coordinates.length - 1, + n = coordinates.length, x = 0, y = 0, a, - b, + b = coordinates[n - 1], c; if (!arguments.length) k = -1 / (6 * coordinates.area()); while (++i < n) { - a = coordinates[i]; - b = coordinates[i + 1]; + a = b; + b = coordinates[i]; c = a[0] * b[1] - b[0] * a[1]; x += (a[0] + b[0]) * c; y += (a[1] + b[1]) * c;
2 d3.geom.min.js
 @@ -1 +1 @@ -(function(){function c(a){var b=0,c=0;for(;;){if(a(b,c))return[b,c];b===0?(b=c+1,c=0):(b-=1,c+=1)}}function d(a,b,c,d){var e,f,g,h,i,j,k;return e=d[a],f=e[0],g=e[1],e=d[b],h=e[0],i=e[1],e=d[c],j=e[0],k=e[1],(k-g)*(h-f)-(i-g)*(j-f)>0}function e(a,b,c){return(c[0]-b[0])*(a[1]-b[1])<(c[1]-b[1])*(a[0]-b[0])}function f(a,b,c,d){var e=a[0],f=b[0],g=c[0],h=d[0],i=a[1],j=b[1],k=c[1],l=d[1],m=e-g,n=f-e,o=h-g,p=i-k,q=j-i,r=l-k,s=(o*p-r*m)/(r*n-o*q);return[e+s*n,i+s*q]}function h(a,b){var c={list:a.map(function(a,b){return{index:b,x:a[0],y:a[1]}}).sort(function(a,b){return a.yb.y?1:a.xb.x?1:0}),bottomSite:null},d={list:[],leftEnd:null,rightEnd:null,init:function(){d.leftEnd=d.createHalfEdge(null,"l"),d.rightEnd=d.createHalfEdge(null,"l"),d.leftEnd.r=d.rightEnd,d.rightEnd.l=d.leftEnd,d.list.unshift(d.leftEnd,d.rightEnd)},createHalfEdge:function(a,b){return{edge:a,side:b,vertex:null,l:null,r:null}},insert:function(a,b){b.l=a,b.r=a.r,a.r.l=b,a.r=b},leftBound:function(a){var b=d.leftEnd;do b=b.r;while(b!=d.rightEnd&&e.rightOf(b,a));return b=b.l,b},del:function(a){a.l.r=a.r,a.r.l=a.l,a.edge=null},right:function(a){return a.r},left:function(a){return a.l},leftRegion:function(a){return a.edge==null?c.bottomSite:a.edge.region[a.side]},rightRegion:function(a){return a.edge==null?c.bottomSite:a.edge.region[g[a.side]]}},e={bisect:function(a,b){var c={region:{l:a,r:b},ep:{l:null,r:null}},d=b.x-a.x,e=b.y-a.y,f=d>0?d:-d,g=e>0?e:-e;return c.c=a.x*d+a.y*e+(d*d+e*e)*.5,f>g?(c.a=1,c.b=e/d,c.c/=d):(c.b=1,c.a=d/e,c.c/=e),c},intersect:function(a,b){var c=a.edge,d=b.edge;if(!c||!d||c.region.r==d.region.r)return null;var e=c.a*d.b-c.b*d.a;if(Math.abs(e)<1e-10)return null;var f=(c.c*d.b-d.c*c.b)/e,g=(d.c*c.a-c.c*d.a)/e,h=c.region.r,i=d.region.r,j,k;h.y=k.region.r.x;return l&&j.side==="l"||!l&&j.side==="r"?null:{x:f,y:g}},rightOf:function(a,b){var c=a.edge,d=c.region.r,e=b.x>d.x;if(e&&a.side==="l")return 1;if(!e&&a.side==="r")return 0;if(c.a===1){var f=b.y-d.y,g=b.x-d.x,h=0,i=0;!e&&c.b<0||e&&c.b>=0?i=h=f>=c.b*g:(i=b.x+b.y*c.b>c.c,c.b<0&&(i=!i),i||(h=1));if(!h){var j=d.x-c.region.l.x;i=c.b*(g*g-f*f)m*m+n*n}return a.side==="l"?i:!i},endPoint:function(a,c,d){a.ep[c]=d;if(!a.ep[g[c]])return;b(a)},distance:function(a,b){var c=a.x-b.x,d=a.y-b.y;return Math.sqrt(c*c+d*d)}},f={list:[],insert:function(a,b,c){a.vertex=b,a.ystar=b.y+c;for(var d=0,e=f.list,g=e.length;dh.ystar||a.ystar==h.ystar&&b.x>h.vertex.x)continue;break}e.splice(d,0,a)},del:function(a){for(var b=0,c=f.list,d=c.length;bp.y&&(q=o,o=p,p=q,u="r"),t=e.bisect(o,p),n=d.createHalfEdge(t,u),d.insert(l,n),e.endPoint(t,g[u],s),r=e.intersect(l,n),r&&(f.del(l),f.insert(l,r,e.distance(r,o))),r=e.intersect(n,m),r&&f.insert(n,r,e.distance(r,o));else break}for(j=d.right(d.leftEnd);j!=d.rightEnd;j=d.right(j))b(j.edge)}function i(){return{leaf:!0,nodes:[],point:null}}function j(a,b,c,d,e,f){if(!a(b,c,d,e,f)){var g=(c+e)*.5,h=(d+f)*.5,i=b.nodes;i[0]&&j(a,i[0],c,d,g,h),i[1]&&j(a,i[1],g,d,e,h),i[2]&&j(a,i[2],c,h,g,f),i[3]&&j(a,i[3],g,h,e,f)}}function k(a){return{x:a[0],y:a[1]}}d3.geom={},d3.geom.contour=function(d,e){var f=e||c(d),g=[],h=f[0],i=f[1],j=0,k=0,l=NaN,m=NaN,n=0;do n=0,d(h-1,i-1)&&(n+=1),d(h,i-1)&&(n+=2),d(h-1,i)&&(n+=4),d(h,i)&&(n+=8),n===6?(j=m===-1?-1:1,k=0):n===9?(j=0,k=l===1?-1:1):(j=a[n],k=b[n]),j!=l&&k!=m&&(g.push([h,i]),l=j,m=k),h+=j,i+=k;while(f[0]!=h||f[1]!=i);return g};var a=[1,0,1,1,-1,0,-1,1,0,0,0,0,-1,0,-1,NaN],b=[0,-1,0,0,0,-1,0,0,1,-1,1,1,0,-1,0,NaN];d3.geom.hull=function(a){if(a.length<3)return[];var b=a.length,c=b-1,e=[],f=[],g,h,i=0,j,k,l,m,n,o,p,q;for(g=1;g=l*l+m*m?e[g].index=-1:(e[n].index=-1,p=e[g].angle,n=g,o=h)):(p=e[g].angle,n=g,o=h);f.push(i);for(g=0,h=0;g<2;++h)e[h].index!==-1&&(f.push(e[h].index),g++);q=f.length;for(;h=0?(c=a.ep.r,d=a.ep.l):(c=a.ep.l,d=a.ep.r),a.a===1?(g=c?c.y:-1e6,e=a.c-a.b*g,h=d?d.y:1e6,f=a.c-a.b*h):(e=c?c.x:-1e6,g=a.c-a.a*e,f=d?d.x:1e6,h=a.c-a.a*f);var i=[e,g],j=[f,h];b[a.region.l.index].push(i,j),b[a.region.r.index].push(i,j)}),b.map(function(b,c){var d=a[c][0],e=a[c][1];return b.forEach(function(a){a.angle=Math.atan2(a[0]-d,a[1]-e)}),b.sort(function(a,b){return a.angle-b.angle}).filter(function(a,c){return!c||a.angle-b[c-1].angle>1e-10})})};var g={l:"r",r:"l"};d3.geom.delaunay=function(a){var b=a.map(function(){return[]}),c=[];return h(a,function(c){b[c.region.l.index].push(a[c.region.r.index])}),b.forEach(function(b,d){var e=a[d],f=e[0],g=e[1];b.forEach(function(a){a.angle=Math.atan2(a[0]-f,a[1]-g)}),b.sort(function(a,b){return a.angle-b.angle});for(var h=0,i=b.length-1;h=g,k=b.y>=h,l=(k<<1)+j;a.leaf=!1,a=a.nodes[l]||(a.nodes[l]=i()),j?c=g:e=g,k?d=h:f=h,n(a,b,c,d,e,f)}var f,g=-1,h=a.length;h&&isNaN(a[0].x)&&(a=a.map(k));if(arguments.length<5)if(arguments.length===3)e=d=c,c=b;else{b=c=Infinity,d=e=-Infinity;while(++gd&&(d=f.x),f.y>e&&(e=f.y);var l=d-b,m=e-c;l>m?e=c+l:d=b+m}var p=i();return p.add=function(a){n(p,a,b,c,d,e)},p.visit=function(a){j(a,p,b,c,d,e)},a.forEach(p.add),p}})(); +(function(){function c(a){var b=0,c=0;for(;;){if(a(b,c))return[b,c];b===0?(b=c+1,c=0):(b-=1,c+=1)}}function d(a,b,c,d){var e,f,g,h,i,j,k;return e=d[a],f=e[0],g=e[1],e=d[b],h=e[0],i=e[1],e=d[c],j=e[0],k=e[1],(k-g)*(h-f)-(i-g)*(j-f)>0}function e(a,b,c){return(c[0]-b[0])*(a[1]-b[1])<(c[1]-b[1])*(a[0]-b[0])}function f(a,b,c,d){var e=a[0],f=b[0],g=c[0],h=d[0],i=a[1],j=b[1],k=c[1],l=d[1],m=e-g,n=f-e,o=h-g,p=i-k,q=j-i,r=l-k,s=(o*p-r*m)/(r*n-o*q);return[e+s*n,i+s*q]}function h(a,b){var c={list:a.map(function(a,b){return{index:b,x:a[0],y:a[1]}}).sort(function(a,b){return a.yb.y?1:a.xb.x?1:0}),bottomSite:null},d={list:[],leftEnd:null,rightEnd:null,init:function(){d.leftEnd=d.createHalfEdge(null,"l"),d.rightEnd=d.createHalfEdge(null,"l"),d.leftEnd.r=d.rightEnd,d.rightEnd.l=d.leftEnd,d.list.unshift(d.leftEnd,d.rightEnd)},createHalfEdge:function(a,b){return{edge:a,side:b,vertex:null,l:null,r:null}},insert:function(a,b){b.l=a,b.r=a.r,a.r.l=b,a.r=b},leftBound:function(a){var b=d.leftEnd;do b=b.r;while(b!=d.rightEnd&&e.rightOf(b,a));return b=b.l,b},del:function(a){a.l.r=a.r,a.r.l=a.l,a.edge=null},right:function(a){return a.r},left:function(a){return a.l},leftRegion:function(a){return a.edge==null?c.bottomSite:a.edge.region[a.side]},rightRegion:function(a){return a.edge==null?c.bottomSite:a.edge.region[g[a.side]]}},e={bisect:function(a,b){var c={region:{l:a,r:b},ep:{l:null,r:null}},d=b.x-a.x,e=b.y-a.y,f=d>0?d:-d,g=e>0?e:-e;return c.c=a.x*d+a.y*e+(d*d+e*e)*.5,f>g?(c.a=1,c.b=e/d,c.c/=d):(c.b=1,c.a=d/e,c.c/=e),c},intersect:function(a,b){var c=a.edge,d=b.edge;if(!c||!d||c.region.r==d.region.r)return null;var e=c.a*d.b-c.b*d.a;if(Math.abs(e)<1e-10)return null;var f=(c.c*d.b-d.c*c.b)/e,g=(d.c*c.a-c.c*d.a)/e,h=c.region.r,i=d.region.r,j,k;h.y=k.region.r.x;return l&&j.side==="l"||!l&&j.side==="r"?null:{x:f,y:g}},rightOf:function(a,b){var c=a.edge,d=c.region.r,e=b.x>d.x;if(e&&a.side==="l")return 1;if(!e&&a.side==="r")return 0;if(c.a===1){var f=b.y-d.y,g=b.x-d.x,h=0,i=0;!e&&c.b<0||e&&c.b>=0?i=h=f>=c.b*g:(i=b.x+b.y*c.b>c.c,c.b<0&&(i=!i),i||(h=1));if(!h){var j=d.x-c.region.l.x;i=c.b*(g*g-f*f)m*m+n*n}return a.side==="l"?i:!i},endPoint:function(a,c,d){a.ep[c]=d;if(!a.ep[g[c]])return;b(a)},distance:function(a,b){var c=a.x-b.x,d=a.y-b.y;return Math.sqrt(c*c+d*d)}},f={list:[],insert:function(a,b,c){a.vertex=b,a.ystar=b.y+c;for(var d=0,e=f.list,g=e.length;dh.ystar||a.ystar==h.ystar&&b.x>h.vertex.x)continue;break}e.splice(d,0,a)},del:function(a){for(var b=0,c=f.list,d=c.length;bp.y&&(q=o,o=p,p=q,u="r"),t=e.bisect(o,p),n=d.createHalfEdge(t,u),d.insert(l,n),e.endPoint(t,g[u],s),r=e.intersect(l,n),r&&(f.del(l),f.insert(l,r,e.distance(r,o))),r=e.intersect(n,m),r&&f.insert(n,r,e.distance(r,o));else break}for(j=d.right(d.leftEnd);j!=d.rightEnd;j=d.right(j))b(j.edge)}function i(){return{leaf:!0,nodes:[],point:null}}function j(a,b,c,d,e,f){if(!a(b,c,d,e,f)){var g=(c+e)*.5,h=(d+f)*.5,i=b.nodes;i[0]&&j(a,i[0],c,d,g,h),i[1]&&j(a,i[1],g,d,e,h),i[2]&&j(a,i[2],c,h,g,f),i[3]&&j(a,i[3],g,h,e,f)}}function k(a){return{x:a[0],y:a[1]}}d3.geom={},d3.geom.contour=function(d,e){var f=e||c(d),g=[],h=f[0],i=f[1],j=0,k=0,l=NaN,m=NaN,n=0;do n=0,d(h-1,i-1)&&(n+=1),d(h,i-1)&&(n+=2),d(h-1,i)&&(n+=4),d(h,i)&&(n+=8),n===6?(j=m===-1?-1:1,k=0):n===9?(j=0,k=l===1?-1:1):(j=a[n],k=b[n]),j!=l&&k!=m&&(g.push([h,i]),l=j,m=k),h+=j,i+=k;while(f[0]!=h||f[1]!=i);return g};var a=[1,0,1,1,-1,0,-1,1,0,0,0,0,-1,0,-1,NaN],b=[0,-1,0,0,0,-1,0,0,1,-1,1,1,0,-1,0,NaN];d3.geom.hull=function(a){if(a.length<3)return[];var b=a.length,c=b-1,e=[],f=[],g,h,i=0,j,k,l,m,n,o,p,q;for(g=1;g=l*l+m*m?e[g].index=-1:(e[n].index=-1,p=e[g].angle,n=g,o=h)):(p=e[g].angle,n=g,o=h);f.push(i);for(g=0,h=0;g<2;++h)e[h].index!==-1&&(f.push(e[h].index),g++);q=f.length;for(;h=0?(c=a.ep.r,d=a.ep.l):(c=a.ep.l,d=a.ep.r),a.a===1?(g=c?c.y:-1e6,e=a.c-a.b*g,h=d?d.y:1e6,f=a.c-a.b*h):(e=c?c.x:-1e6,g=a.c-a.a*e,f=d?d.x:1e6,h=a.c-a.a*f);var i=[e,g],j=[f,h];b[a.region.l.index].push(i,j),b[a.region.r.index].push(i,j)}),b.map(function(b,c){var d=a[c][0],e=a[c][1];return b.forEach(function(a){a.angle=Math.atan2(a[0]-d,a[1]-e)}),b.sort(function(a,b){return a.angle-b.angle}).filter(function(a,c){return!c||a.angle-b[c-1].angle>1e-10})})};var g={l:"r",r:"l"};d3.geom.delaunay=function(a){var b=a.map(function(){return[]}),c=[];return h(a,function(c){b[c.region.l.index].push(a[c.region.r.index])}),b.forEach(function(b,d){var e=a[d],f=e[0],g=e[1];b.forEach(function(a){a.angle=Math.atan2(a[0]-f,a[1]-g)}),b.sort(function(a,b){return a.angle-b.angle});for(var h=0,i=b.length-1;h=g,k=b.y>=h,l=(k<<1)+j;a.leaf=!1,a=a.nodes[l]||(a.nodes[l]=i()),j?c=g:e=g,k?d=h:f=h,n(a,b,c,d,e,f)}var f,g=-1,h=a.length;h&&isNaN(a[0].x)&&(a=a.map(k));if(arguments.length<5)if(arguments.length===3)e=d=c,c=b;else{b=c=Infinity,d=e=-Infinity;while(++gd&&(d=f.x),f.y>e&&(e=f.y);var l=d-b,m=e-c;l>m?e=c+l:d=b+m}var p=i();return p.add=function(a){n(p,a,b,c,d,e)},p.visit=function(a){j(a,p,b,c,d,e)},a.forEach(p.add),p}})();
8 src/geom/polygon.js
 @@ -15,16 +15,16 @@ d3.geom.polygon = function(coordinates) { coordinates.centroid = function(k) { var i = -1, - n = coordinates.length - 1, + n = coordinates.length, x = 0, y = 0, a, - b, + b = coordinates[n - 1], c; if (!arguments.length) k = -1 / (6 * coordinates.area()); while (++i < n) { - a = coordinates[i]; - b = coordinates[i + 1]; + a = b; + b = coordinates[i]; c = a[0] * b[1] - b[0] * a[1]; x += (a[0] + b[0]) * c; y += (a[1] + b[1]) * c;
58 test/geom/polygon-test.js
 @@ -8,49 +8,75 @@ var vows = require("vows"), var suite = vows.describe("d3.geom.polygon"); suite.addBatch({ - "counterclockwise polygon (last point equal to start point)": { + "closed counterclockwise unit square": { topic: function() { return d3.geom.polygon([[0, 0], [0, 1], [1, 1], [1, 0], [0, 0]]); }, - "area": function(polygon) { + "has area 1": function(polygon) { assert.equal(polygon.area(), 1); }, - "centroid": function(polygon) { + "has centroid ⟨.5,.5⟩": function(polygon) { assert.deepEqual(polygon.centroid(), [.5, .5]); } }, - "counterclockwise polygon (implicitly ending at start point)": { + "closed clockwise unit square": { topic: function() { - return d3.geom.polygon([[0, 0], [0, 1], [1, 1], [1, 0]]); + return d3.geom.polygon([[0, 0], [1, 0], [1, 1], [0, 1], [0, 0]]); }, - "area": function(polygon) { - assert.equal(polygon.area(), 1); + "has area 1": function(polygon) { + assert.equal(polygon.area(), -1); }, - "centroid": function(polygon) { + "has centroid ⟨.5,.5⟩": function(polygon) { assert.deepEqual(polygon.centroid(), [.5, .5]); } }, - "clockwise polygon (last point equal to start point)": { + "closed clockwise triangle": { topic: function() { - return d3.geom.polygon([[0, 0], [1, 0], [1, 1], [0, 1], [0, 0]]); + return d3.geom.polygon([[1, 1], [3, 2], [2, 3], [1, 1]]); }, - "area": function(polygon) { - assert.equal(polygon.area(), -1); + "has area 1.5": function(polygon) { + assert.equal(polygon.area(), -1.5); + }, + "has centroid ⟨2,2⟩": function(polygon) { + var centroid = polygon.centroid(); + assert.inDelta(centroid[0], 2, 1e-6); + assert.inDelta(centroid[1], 2, 1e-6); + } + }, + "open counterclockwise unit square": { + topic: function() { + return d3.geom.polygon([[0, 0], [0, 1], [1, 1], [1, 0]]); }, - "centroid": function(polygon) { + "has area 1": function(polygon) { + assert.equal(polygon.area(), 1); + }, + "has centroid ⟨.5,.5⟩": function(polygon) { assert.deepEqual(polygon.centroid(), [.5, .5]); } }, - "clockwise polygon (implicitly ending at start point)": { + "open clockwise unit square": { topic: function() { return d3.geom.polygon([[0, 0], [1, 0], [1, 1], [0, 1]]); }, - "area": function(polygon) { + "has area 1": function(polygon) { assert.equal(polygon.area(), -1); }, - "centroid": function(polygon) { + "has centroid ⟨.5,.5⟩": function(polygon) { assert.deepEqual(polygon.centroid(), [.5, .5]); } + }, + "open clockwise triangle": { + topic: function() { + return d3.geom.polygon([[1, 1], [3, 2], [2, 3]]); + }, + "has area 1.5": function(polygon) { + assert.equal(polygon.area(), -1.5); + }, + "has centroid ⟨2,2⟩": function(polygon) { + var centroid = polygon.centroid(); + assert.inDelta(centroid[0], 2, 1e-6); + assert.inDelta(centroid[1], 2, 1e-6); + } } });