2.1.1 useful routine distanceInMeters added to API and unit test

mapcodefoundation · mapcodefoundation · commit 808d87aecfa8 · 2015-08-26T20:16:03.000+02:00
diff --git a/README.md b/README.md
@@ -43,6 +43,10 @@ of the Mapcode library by Rijn Buve and Matthew Lowden.
 
 # Version History
 
+* 2.1.1 - August 2015
+
+    Added useful routine DistanceInMeters to API
+
 * 2.1.0 - August 2015
 
     Rewrote fraction floating points to integer arithmetic
diff --git a/mapcode.js b/mapcode.js
@@ -121,7 +121,7 @@ var mapcode_dataversion = "2.0";
 
 // *************************** mapcode_org *********************
 
-var mapcode_javaversion = '2.1.0/Data2.0';
+var mapcode_javaversion = '2.1.1/Data2.0';
 
 /// PRIVATE returns string without leading spaces and plus-signs, and trailing spaces
 function trim(str) {
@@ -1939,26 +1939,11 @@ function master_encode(orgy, orgx, tn, isrecursive, stop_with_one_result, alloww
 /// PUBLIC returns {distance,width,height}, the distance between two coordinates, and the longitudinal distance ("width") and latitudinal distance ("height") - all expressed in meters
 /// Warning: accurate only for coordinates within a few hundred meters of each other
 function distanceInMeters(latDeg1, lonDeg1, latDeg2, lonDeg2) {
-    var worstParallel = 0; // assume equator
-    if (latDeg1 > latDeg2) {
-        if (latDeg1 < 0) {
-            worstParallel = latDeg2;
-        } else if (latDeg2 > 0) {
-            worstParallel = latDeg1;
-        }
-    }
-    else {
-        if (latDeg2 < 0) {
-            worstParallel = latDeg1;
-        } else if (latDeg1 > 0) {
-            worstParallel = latDeg2;
-        }
-    }
-    var dy = (latDeg2 - latDeg1) * 1000000 / 9;
     if (lonDeg1 < 0 && lonDeg2 > 1) { lonDeg1 += 360; }
     if (lonDeg2 < 0 && lonDeg1 > 1) { lonDeg2 += 360; }
-    var dx = (lonDeg2 - lonDeg1) * Math.cos(Math.PI * worstParallel / 180) * 1000000 / 9;
-    return {distance: Math.sqrt(dx * dx + dy * dy), width: (dx < 0 ? -dx : dx), height: (dy < 0 ? -dy : dy)};
+    var dx = 111319.49079327 * (lonDeg2 - lonDeg1) * Math.cos((latDeg1 + latDeg2) * Math.PI / 360.0);
+    var dy = 110946.25213273 * (latDeg2 - latDeg1);
+    return Math.sqrt(dx * dx + dy * dy);
 }
 
 /// PUBLIC convert a mapcode (skipping the territory abbreviation) into a particular alphabet
diff --git a/mapcode_library_js.doc b/mapcode_library_js.doc
diff --git a/unittest/test_encodes.js b/unittest/test_encodes.js
@@ -1,6 +1,26 @@
 
 var testdata = [
 
+// some notable examples
+"", 55.01500050000000, 20.94998200000000, 0,0,
+"", 55.01502500000000, 20.95002500000000, 0,0,
+"", 21.61999950000000, -102.02419949999999, 0,0,
+"", 21.62000350000000, -102.02423750000000, 0,0,
+"", 29.72705500000000, 73.87498650000001,0,0, 
+"", 29.72702500000000, 73.87502499999999,0,0,
+"", 28.67999500000000, 78.71705600000000,0,0,
+"", 28.68002500000000, 78.71702500000001,0,0,
+"", 5.785780,169.791750, 0,0, // grid
+"", -9.34015920,-171.99626665, 0,0, // encompassing
+"", 49.4632595,  -2.559890, 0,0, // inner grid
+"", 49.4632625,  -2.5599018, 0,0, // old 
+"", 47.1495405,   9.5319995, 0,0, // inner grid AUT
+"", 41.90350000000000, 12.45200000000000 , 0,0,
+"", 12.16892100000000, -68.26226699999999, 0,0,
+"", 21.90678099999900, -72.05700000000100, 0,0,
+"", 21.90669750000000 , -72.05699749999999, 0,0,
+"", 21.90678099999900, -72.05700000000100, 0,0,
+
 "IN-NL WKS.H6",26.904854, 95.138497, 5,21,
 "NLD 00.XX",52.383984,4.865401375, 0,0,
 
diff --git a/unittest/unittest.html b/unittest/unittest.html
@@ -15,7 +15,7 @@
 </head>
 <body>
 
-Mapcode Javascript Unit Test 2.1.0<BR>
+Mapcode Javascript Unit Test 2.1.1<BR>
 <DIV id="out"></DIV>
 <DIV id="perc"></DIV>
 
@@ -137,7 +137,7 @@
 			nrTests++;
 			var p = decode(str);
 			if ( p ) {
-				var dm = distanceInMeters(y, x, p.y, p.x).distance;
+				var dm = distanceInMeters(y, x, p.y, p.x);
 				var maxerror = maxErrorForPrecision[precision];
 				if (dm>maxerror) {
 					nrErrors++;
@@ -336,6 +336,44 @@
   }
 }
 
+function distance_tests()
+{
+	if (mapcode_javaversion>'2.1.0') {
+		var i,distance;
+		var coordpairs = [
+			// lat1, lon1, lat2, lon2, expected distance * 100000
+			1,1,1,1,0,
+			0,0,0,1,11131949079,
+			89,0,89,1,194279300,
+			3,0,3,1,11116693130,
+			-3,0,-3,1,11116693130,
+			-3,-179.5,-3,179.5,11116693130,
+			-3,179.5,-3,-179.5,11116693130,
+			3,8,3,9,11116693130,
+			3,-8,3,-9,11116693130,
+			3,-0.5,3,0.5,11116693130,
+			54,5,54.000001,5,11095,
+			54,5,54,5.000001,6543,
+			54,5,54.000001,5.000001,12880,
+			90,0,90,50,0,
+			0.11,0.22,0.12,0.2333,185011466,
+		-1];
+		
+		for(i=0;coordpairs[i]!=-1;i+=5) {
+			nrTests++;
+			distance = distanceInMeters( 
+				coordpairs[i],coordpairs[i+1],
+				coordpairs[i+2],coordpairs[i+3]);
+			if ( Math.round(100000.0 * distance) != coordpairs[i+4] ) {
+				nrErrors++;
+				out('*** ERROR *** distanceInMeters '+i+' failed: '+distance);
+			}
+		}
+	}
+}
+
+
+
 var myVar = setInterval(function(){stepper()},20);
 var dostep=0;
 function stepper()
@@ -351,6 +389,8 @@
 			alphabet_tests();
 			break;
 		case 3:
+			out('<HR>Distance tests');
+			distance_tests();
 			out('<HR>Territory tests');
 			out( (ccode_earth+1) + ' territories');
 			break;
