greatest, least, greatestIndex and leastIndex ignore nulls

closes #208

Author: Fil

src/greatest.js

@@ -7,19 +7,21 @@ export default function greatest(values, compare = ascending) {
     let maxValue;
     for (const element of values) {
       const value = compare(element);
-      if (defined
+      if ((defined
           ? ascending(value, maxValue) > 0
-          : ascending(value, value) === 0) {
+          : ascending(value, value) === 0
+        ) && value !== null) {
         max = element;
         maxValue = value;
         defined = true;
       }
     }
   } else {
     for (const value of values) {
-      if (defined
+      if ((defined
           ? compare(value, max) > 0
-          : compare(value, value) === 0) {
+          : compare(value, value) === 0
+        ) && value !== null) {
         max = value;
         defined = true;
       }

src/greatestIndex.js

@@ -8,9 +8,10 @@ export default function greatestIndex(values, compare = ascending) {
   let index = -1;
   for (const value of values) {
     ++index;
-    if (max < 0
+    if ((max < 0
         ? compare(value, value) === 0
-        : compare(value, maxValue) > 0) {
+        : compare(value, maxValue) > 0
+      ) && value !== null) {
       maxValue = value;
       max = index;
     }

src/least.js

@@ -7,19 +7,21 @@ export default function least(values, compare = ascending) {
     let minValue;
     for (const element of values) {
       const value = compare(element);
-      if (defined
+      if ((defined
           ? ascending(value, minValue) < 0
-          : ascending(value, value) === 0) {
+          : ascending(value, value) === 0
+        ) && value !== null) {
         min = element;
         minValue = value;
         defined = true;
       }
     }
   } else {
     for (const value of values) {
-      if (defined
+      if ((defined
           ? compare(value, min) < 0
-          : compare(value, value) === 0) {
+          : compare(value, value) === 0
+        ) && value !== null) {
         min = value;
         defined = true;
       }

src/leastIndex.js

@@ -8,9 +8,10 @@ export default function leastIndex(values, compare = ascending) {
   let index = -1;
   for (const value of values) {
     ++index;
-    if (min < 0
+    if ((min < 0
         ? compare(value, value) === 0
-        : compare(value, minValue) < 0) {
+        : compare(value, minValue) < 0
+      ) && value !== null) {
       minValue = value;
       min = index;
     }

test/greatest-test.js

@@ -46,6 +46,14 @@ tape("greatest(array) returns the first of equal values", (test) => {
   test.deepEqual(d3.greatest([3, 2, 2, 1, 1, 0, 0, 0, 3, 0].map(box), ascendingValue), {value: 3, index: 0});
 });
 
+tape("greatest(array) ignores nulls", (test) => {
+  test.deepEqual(d3.greatest([null, -2, null]), -2);
+});
+
+tape("greatest(array, accessor) ignores nulls", (test) => {
+  test.deepEqual(d3.greatest([null, -2, null], d => d), -2);
+});
+
 function box(value, index) {
   return {value, index};
 }

test/greatestIndex-test.js

@@ -45,3 +45,11 @@ tape("greatestIndex(array) returns the first of equal values", (test) => {
   test.strictEqual(d3.greatestIndex([-2, -2, -1, -1, 0, 0, 0, -3, 0]), 4);
   test.strictEqual(d3.greatestIndex([-3, -2, -2, -1, -1, 0, 0, 0, -3, 0], d3.descending), 0);
 });
+
+tape("greatestIndex(array) ignores nulls", (test) => {
+  test.deepEqual(d3.greatestIndex([null, -2, null]), 1);
+});
+
+tape("greatestIndex(array, accessor) ignores nulls", (test) => {
+  test.deepEqual(d3.greatestIndex([null, -2, null], d => d), 1);
+});

test/least-test.js

@@ -46,6 +46,14 @@ tape("least(array) returns the first of equal values", (test) => {
   test.deepEqual(d3.least([3, 2, 2, 1, 1, 0, 0, 0, 3, 0].map(box), descendingValue), {value: 3, index: 0});
 });
 
+tape("least(array) ignores nulls", (test) => {
+  test.deepEqual(d3.least([null, 2, null]), 2);
+});
+
+tape("least(array, accessor) ignores nulls", (test) => {
+  test.deepEqual(d3.least([null, 2, null], d => d), 2);
+});
+
 function box(value, index) {
   return {value, index};
 }

test/leastIndex-test.js

@@ -45,3 +45,11 @@ tape("leastIndex(array) returns the first of equal values", (test) => {
   test.strictEqual(d3.leastIndex([2, 2, 1, 1, 0, 0, 0, 3, 0]), 4);
   test.strictEqual(d3.leastIndex([3, 2, 2, 1, 1, 0, 0, 0, 3, 0], d3.descending), 0);
 });
+
+tape("leastIndex(array) ignores nulls", (test) => {
+  test.deepEqual(d3.leastIndex([null, 2, null]), 1);
+});
+
+tape("leastIndex(array, accessor) ignores nulls", (test) => {
+  test.deepEqual(d3.leastIndex([null, 2, null], d => d), 1);
+});