d3.min & d3.max: ignore NaN at [0].

Note: this now returns Infinity and -Infinity for zero-element arrays, whereas
previously an error would have occurred.

Fixes #161.

d3.js

@@ -41,27 +41,25 @@ d3.descending = function(a, b) {
   return b < a ? -1 : b > a ? 1 : 0;
 };
 d3.min = function(array, f) {
-  var i = 0,
+  var i = -1,
       n = array.length,
-      a = array[0],
+      a = Infinity,
       b;
   if (arguments.length === 1) {
     while (++i < n) if (a > (b = array[i])) a = b;
   } else {
-    a = f.call(array, a, 0);
     while (++i < n) if (a > (b = f.call(array, array[i], i))) a = b;
   }
   return a;
 };
 d3.max = function(array, f) {
-  var i = 0,
+  var i = -1,
       n = array.length,
-      a = array[0],
+      a = -Infinity,
       b;
   if (arguments.length === 1) {
     while (++i < n) if (a < (b = array[i])) a = b;
   } else {
-    a = f.call(array, a, 0);
     while (++i < n) if (a < (b = f.call(array, array[i], i))) a = b;
   }
   return a;

src/core/max.js

@@ -1,12 +1,11 @@
 d3.max = function(array, f) {
-  var i = 0,
+  var i = -1,
       n = array.length,
-      a = array[0],
+      a = -Infinity,
       b;
   if (arguments.length === 1) {
     while (++i < n) if (a < (b = array[i])) a = b;
   } else {
-    a = f.call(array, a, 0);
     while (++i < n) if (a < (b = f.call(array, array[i], i))) a = b;
   }
   return a;

src/core/min.js

@@ -1,12 +1,11 @@
 d3.min = function(array, f) {
-  var i = 0,
+  var i = -1,
       n = array.length,
-      a = array[0],
+      a = Infinity,
       b;
   if (arguments.length === 1) {
     while (++i < n) if (a > (b = array[i])) a = b;
   } else {
-    a = f.call(array, a, 0);
     while (++i < n) if (a > (b = f.call(array, array[i], i))) a = b;
   }
   return a;

tests/test-max.js

@@ -16,3 +16,11 @@ console.log("  " + d3.max([1, 2, 3, 4, 5], function(d, i) {
   return i;
 }));
 console.log("");
+
+console.log("max with first element NaN:");
+console.log("  " + d3.max([NaN, 1, 2, 3, 4, 5]));
+console.log("");
+
+console.log("max with last element NaN:");
+console.log("  " + d3.max([1, 2, 3, 4, 5, NaN]));
+console.log("");

tests/test-max.out

@@ -7,3 +7,9 @@ max with accessor function:
 max index:
   4
 
+max with first element NaN:
+  5
+
+max with last element NaN:
+  5
+

tests/test-min.js

@@ -16,3 +16,11 @@ console.log("  " + d3.min([1, 2, 3, 4, 5], function(d, i) {
   return i;
 }));
 console.log("");
+
+console.log("min with first element NaN:");
+console.log("  " + d3.min([NaN, 1, 2, 3, 4, 5]));
+console.log("");
+
+console.log("min with last element NaN:");
+console.log("  " + d3.min([1, 2, 3, 4, 5, NaN]));
+console.log("");

tests/test-min.out

@@ -7,3 +7,9 @@ min with accessor function:
 min index:
   0
 
+min with first element NaN:
+  1
+
+min with last element NaN:
+  1
+