Merge pull request #363 from jasondavies/extent

Use single loop for d3.extent.
d3 · Nov 4, 2011 · a9043b9 · a9043b9
2 parents 2b42dec + d11b5d9
commit a9043b9
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Showing 4 changed files with 41 additions and 6 deletions.
diff --git a/d3.js b/d3.js
@@ -106,8 +106,25 @@ d3.max = function(array, f) {
   return a;
 };
 d3.extent = function(array, f) {
-  if (arguments.length > 1) array = array.map(f);
-  return [d3.min(array), d3.max(array)];
+  var i = -1,
+      n = array.length,
+      a,
+      b,
+      c;
+  if (arguments.length === 1) {
+    while (++i < n && ((a = c = array[i]) == null || a != a)) a = c = undefined;
+    while (++i < n) if ((b = array[i]) != null) {
+      if (a > b) a = b;
+      if (c < b) c = b;
+    }
+  } else {
+    while (++i < n && ((a = c = f.call(array, array[i], i)) == null || a != a)) a = undefined;
+    while (++i < n) if ((b = f.call(array, array[i], i)) != null) {
+      if (a > b) a = b;
+      if (c < b) c = b;
+    }
+  }
+  return [a, c];
 };
 d3.random = {
   normal: function(mean, deviation) {

diff --git a/d3.min.js b/d3.min.js
diff --git a/src/core/extent.js b/src/core/extent.js
@@ -1,4 +1,21 @@
 d3.extent = function(array, f) {
-  if (arguments.length > 1) array = array.map(f);
-  return [d3.min(array), d3.max(array)];
+  var i = -1,
+      n = array.length,
+      a,
+      b,
+      c;
+  if (arguments.length === 1) {
+    while (++i < n && ((a = c = array[i]) == null || a != a)) a = c = undefined;
+    while (++i < n) if ((b = array[i]) != null) {
+      if (a > b) a = b;
+      if (c < b) c = b;
+    }
+  } else {
+    while (++i < n && ((a = c = f.call(array, array[i], i)) == null || a != a)) a = undefined;
+    while (++i < n) if ((b = f.call(array, array[i], i)) != null) {
+      if (a > b) a = b;
+      if (c < b) c = b;
+    }
+  }
+  return [a, c];
 };
diff --git a/test/core/extent-test.js b/test/core/extent-test.js
@@ -26,6 +26,7 @@ suite.addBatch({
       assert.deepEqual(extent([NaN, 1, 2, 3, 4, 5]), [1, 5]);
       assert.deepEqual(extent([1, 2, 3, 4, 5, NaN]), [1, 5]);
       assert.deepEqual(extent([10, null, 3, undefined, 5, NaN]), [3, 10]);
+      assert.deepEqual(extent([-1, null, -3, undefined, -5, NaN]), [-5, -1]);
     },
     "compares heterogenous types as numbers": function(extent) {
       assert.deepEqual(extent([20, "3"]), ["3", 20]);