Fix segmentReduce & segmentEach @turf/meta

packages/turf-meta/README.md

@@ -510,9 +510,9 @@ Callback for segmentEach
 **Parameters**
 
 -   `currentSegment` **[Feature](http://geojson.org/geojson-spec.html#feature-objects)<[LineString](http://geojson.org/geojson-spec.html#linestring)>** The current segment being processed.
--   `featureIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The index of the current element being processed in the array, starts at index 0.
--   `featureSubIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The subindex of the current element being processed in the
-    array. Starts at index 0 and increases for each iterating line segment.
+-   `segmentIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The segmentIndex currently being processed, starts at index 0.
+-   `featureIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The featureIndex currently being processed, starts at index 0.
+-   `featureSubIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The featureSubIndex currently being processed, starts at index 0.
 -   `geojson`  
 -   `callback`  
 
@@ -536,6 +536,7 @@ var polygon = turf.polygon([[[-50, 5], [-40, -10], [-50, -10], [-40, 5], [-50, 5
 // Iterate over GeoJSON by 2-vertex segments
 turf.segmentEach(polygon, function (currentSegment, featureIndex, featureSubIndex) {
   //= currentSegment
+  //= segmentIndex
   //= featureIndex
   //= featureSubIndex
 });
@@ -571,10 +572,9 @@ If an initialValue is not provided:
 -   `previousValue` **\[Any]** The accumulated value previously returned in the last invocation
     of the callback, or initialValue, if supplied.
 -   `currentSegment` **\[[Feature](http://geojson.org/geojson-spec.html#feature-objects)<[LineString](http://geojson.org/geojson-spec.html#linestring)>]** The current segment being processed.
--   `currentIndex` **\[[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)]** The index of the current element being processed in the
-    array. Starts at index 0, if an initialValue is provided, and at index 1 otherwise.
--   `currentSubIndex` **\[[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)]** The subindex of the current element being processed in the
-    array. Starts at index 0 and increases for each iterating line segment.
+-   `segmentIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The segmentIndex currently being processed, starts at index 0.
+-   `featureIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The featureIndex currently being processed, starts at index 0.
+-   `featureSubIndex` **[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** The featureSubIndex currently being processed, starts at index 0.
 -   `geojson`  
 -   `callback`  
 -   `initialValue`  
@@ -596,11 +596,12 @@ Reduce 2-vertex line segment in any GeoJSON object, similar to Array.reduce()
 var polygon = turf.polygon([[[-50, 5], [-40, -10], [-50, -10], [-40, 5], [-50, 5]]]);
 
 // Iterate over GeoJSON by 2-vertex segments
-turf.segmentReduce(polygon, function (previousSegment, currentSegment, currentIndex, currentSubIndex) {
+turf.segmentReduce(polygon, function (previousSegment, currentSegment, segmentIndex, featureIndex, featureSubIndex) {
   //= previousSegment
   //= currentSegment
-  //= currentIndex
-  //= currentSubIndex
+  //= segmentInex
+  //= featureIndex
+  //= featureSubIndex
   return currentSegment
 });
 

packages/turf-meta/index.js

@@ -707,9 +707,9 @@ export function flattenReduce(geojson, callback, initialValue) {
  *
  * @callback segmentEachCallback
  * @param {Feature<LineString>} currentSegment The current segment being processed.
- * @param {number} featureIndex The index of the current element being processed in the array, starts at index 0.
- * @param {number} featureSubIndex The subindex of the current element being processed in the
- * array. Starts at index 0 and increases for each iterating line segment.
+ * @param {number} segmentIndex The segmentIndex currently being processed, starts at index 0.
+ * @param {number} featureIndex The featureIndex currently being processed, starts at index 0.
+ * @param {number} featureSubIndex The featureSubIndex currently being processed, starts at index 0.
  * @returns {void}
  */
 
@@ -726,6 +726,7 @@ export function flattenReduce(geojson, callback, initialValue) {
  * // Iterate over GeoJSON by 2-vertex segments
  * turf.segmentEach(polygon, function (currentSegment, featureIndex, featureSubIndex) {
  *   //= currentSegment
+ *   //= segmentIndex
  *   //= featureIndex
  *   //= featureSubIndex
  * });
@@ -737,8 +738,9 @@ export function flattenReduce(geojson, callback, initialValue) {
  * });
  */
 export function segmentEach(geojson, callback) {
-    flattenEach(geojson, function (feature, featureIndex) {
-        var featureSubIndex = 0;
+    flattenEach(geojson, function (feature, featureIndex, featureSubIndex) {
+        var segmentIndex = 0;
+
         // Exclude null Geometries
         if (!feature.geometry) return;
         // (Multi)Point geometries do not contain segments therefore they are ignored during this operation.
@@ -748,8 +750,8 @@ export function segmentEach(geojson, callback) {
         // Generate 2-vertex line segments
         coordReduce(feature, function (previousCoords, currentCoord) {
             var currentSegment = lineString([previousCoords, currentCoord], feature.properties);
-            callback(currentSegment, featureIndex, featureSubIndex);
-            featureSubIndex++;
+            callback(currentSegment, segmentIndex, featureIndex, featureSubIndex);
+            segmentIndex++;
             return currentCoord;
         });
     });
@@ -773,10 +775,9 @@ export function segmentEach(geojson, callback) {
  * @param {*} [previousValue] The accumulated value previously returned in the last invocation
  * of the callback, or initialValue, if supplied.
  * @param {Feature<LineString>} [currentSegment] The current segment being processed.
- * @param {number} [currentIndex] The index of the current element being processed in the
- * array. Starts at index 0, if an initialValue is provided, and at index 1 otherwise.
- * @param {number} [currentSubIndex] The subindex of the current element being processed in the
- * array. Starts at index 0 and increases for each iterating line segment.
+ * @param {number} segmentIndex The segmentIndex currently being processed, starts at index 0.
+ * @param {number} featureIndex The featureIndex currently being processed, starts at index 0.
+ * @param {number} featureSubIndex The featureSubIndex currently being processed, starts at index 0.
  */
 
 /**
@@ -791,11 +792,12 @@ export function segmentEach(geojson, callback) {
  * var polygon = turf.polygon([[[-50, 5], [-40, -10], [-50, -10], [-40, 5], [-50, 5]]]);
  *
  * // Iterate over GeoJSON by 2-vertex segments
- * turf.segmentReduce(polygon, function (previousSegment, currentSegment, currentIndex, currentSubIndex) {
+ * turf.segmentReduce(polygon, function (previousSegment, currentSegment, segmentIndex, featureIndex, featureSubIndex) {
  *   //= previousSegment
  *   //= currentSegment
- *   //= currentIndex
- *   //= currentSubIndex
+ *   //= segmentInex
+ *   //= featureIndex
+ *   //= featureSubIndex
  *   return currentSegment
  * });
  *
@@ -808,9 +810,11 @@ export function segmentEach(geojson, callback) {
  */
 export function segmentReduce(geojson, callback, initialValue) {
     var previousValue = initialValue;
-    segmentEach(geojson, function (currentSegment, currentIndex, currentSubIndex) {
-        if (currentIndex === 0 && initialValue === undefined) previousValue = currentSegment;
-        else previousValue = callback(previousValue, currentSegment, currentIndex, currentSubIndex);
+    var started = false;
+    segmentEach(geojson, function (currentSegment, segmentIndex, featureIndex, featureSubIndex) {
+        if (started === false && initialValue === undefined) previousValue = currentSegment;
+        else previousValue = callback(previousValue, currentSegment, segmentIndex, featureIndex, featureSubIndex);
+        started = true;
     });
     return previousValue;
 }

packages/turf-meta/test.js

@@ -442,44 +442,64 @@ test('segmentReduce', t => {
     t.end();
 });
 
+test('segmentReduce -- no initialValue', t => {
+    const segments = [];
+    var total = 0;
+    meta.segmentReduce(poly.geometry, (previousValue, currentSegment) => {
+        segments.push(currentSegment);
+        total++;
+    });
+    t.equal(segments[0].geometry.coordinates.length, 2);
+    t.equal(total, 2);
+    t.end();
+});
+
 const geojsonSegments = featureCollection([
-    point([0, 1]),
-    lineString([[0, 0], [2, 2], [4, 4]]), // subIndex = 0, 1
-    polygon([[[5, 5], [0, 0], [2, 2], [4, 4], [5, 5]]]), // subIndex = 0, 1, 2, 3
-    point([0, 1]),
-    lineString([[0, 0], [2, 2], [4, 4]]) // subIndex = 0, 1
+    point([0, 1]), // ignored
+    lineString([[0, 0], [2, 2], [4, 4]]),
+    polygon([[[5, 5], [0, 0], [2, 2], [4, 4], [5, 5]]]),
+    point([0, 1]), // ignored
+    multiLineString([
+        [[0, 0], [2, 2], [4, 4]],
+        [[0, 0], [2, 2], [4, 4]]
+    ])
 ]);
 
 test('segmentEach -- index & subIndex', t => {
-    const index = [];
-    const subIndex = [];
+    const segmentIndexes = [];
+    const featureIndexes = [];
+    const featureSubIndexes = [];
     let total = 0;
 
-    meta.segmentEach(geojsonSegments, (segment, featureIndex, featureSubIndex) => {
-        index.push(featureIndex);
-        subIndex.push(featureSubIndex);
+    meta.segmentEach(geojsonSegments, (segment, segmentIndex, featureIndex, featureSubIndex) => {
+        segmentIndexes.push(segmentIndex);
+        featureIndexes.push(featureIndex);
+        featureSubIndexes.push(featureSubIndex);
         total++;
     });
-    t.equal(total, 8, 'total');
-    t.deepEqual(index, [1, 1, 2, 2, 2, 2, 4, 4], 'index');
-    t.deepEqual(subIndex, [0, 1, 0, 1, 2, 3, 0, 1], 'subIndex');
+    t.equal(total, 10, 'total');
+    t.deepEqual(segmentIndexes, [0, 1, 0, 1, 2, 3, 0, 1, 0, 1], 'segmentEach.segmentIndex');
+    t.deepEqual(featureIndexes, [1, 1, 2, 2, 2, 2, 4, 4, 4, 4], 'segmentEach.featureIndex');
+    t.deepEqual(featureSubIndexes, [0, 0, 0, 0, 0, 0, 0, 0, 1, 1], 'segmentEach.featureSubIndex');
     t.end();
 });
 
 test('segmentReduce -- index & subIndex', t => {
-    const index = [];
-    const subIndex = [];
-
-    const total = meta.segmentReduce(geojsonSegments, (previousValue, segment, featureIndex, featureSubIndex) => {
-        index.push(featureIndex);
-        subIndex.push(featureSubIndex);
-        previousValue++;
-        return previousValue;
-    }, 0);
+    const segmentIndexes = [];
+    const featureIndexes = [];
+    const featureSubIndexes = [];
+    let total = 0;
 
-    t.equal(total, 8, 'total');
-    t.deepEqual(index, [1, 1, 2, 2, 2, 2, 4, 4], 'index');
-    t.deepEqual(subIndex, [0, 1, 0, 1, 2, 3, 0, 1], 'subIndex');
+    meta.segmentReduce(geojsonSegments, (previousValue, segment, segmentIndex, featureIndex, featureSubIndex) => {
+        segmentIndexes.push(segmentIndex);
+        featureIndexes.push(featureIndex);
+        featureSubIndexes.push(featureSubIndex);
+        total++;
+    });
+    t.equal(total, 9, 'total');
+    t.deepEqual(segmentIndexes, [1, 0, 1, 2, 3, 0, 1, 0, 1], 'segmentEach.segmentIndex');
+    t.deepEqual(featureIndexes, [1, 2, 2, 2, 2, 4, 4, 4, 4], 'segmentEach.featureIndex');
+    t.deepEqual(featureSubIndexes, [0, 0, 0, 0, 0, 0, 0, 1, 1], 'segmentEach.featureSubIndex');
     t.end();
 });