Fix #117 - use midpoint when collapsed.

d3 · Jan 26, 2019 · b0bdca4 · b0bdca4
1 parent 30876a5
commit b0bdca4
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Showing 3 changed files with 13 additions and 13 deletions.
diff --git a/src/continuous.js b/src/continuous.js
@@ -13,7 +13,7 @@ export function identity(x) {
 function normalize(a, b) {
   return (b -= (a = +a))
       ? function(x) { return (x - a) / b; }
-      : constant(b);
+      : constant(isNaN(b) ? NaN : 0.5);
 }
 
 function clamper(domain) {

diff --git a/test/linear-test.js b/test/linear-test.js
@@ -45,9 +45,9 @@ tape("linear(x) ignores extra domain values if the range is smaller than the dom
   test.end();
 });
 
-tape("linear(x) maps an empty domain to the range start", function(test) {
-  test.equal(scale.scaleLinear().domain([0, 0]).range([1, 2])(0), 1);
-  test.equal(scale.scaleLinear().domain([0, 0]).range([2, 1])(1), 2);
+tape("linear(x) maps an empty domain to the middle of the range", function(test) {
+  test.equal(scale.scaleLinear().domain([0, 0]).range([1, 2])(0), 1.5);
+  test.equal(scale.scaleLinear().domain([0, 0]).range([2, 1])(1), 1.5);
   test.end();
 });
 
@@ -91,9 +91,9 @@ tape("linear.invert(y) maps a range value y to a domain value x", function(test)
   test.end();
 });
 
-tape("linear.invert(y) maps an empty range to the domain start", function(test) {
-  test.equal(scale.scaleLinear().domain([1, 2]).range([0, 0]).invert(0), 1);
-  test.equal(scale.scaleLinear().domain([2, 1]).range([0, 0]).invert(1), 2);
+tape("linear.invert(y) maps an empty range to the middle of the domain", function(test) {
+  test.equal(scale.scaleLinear().domain([1, 2]).range([0, 0]).invert(0), 1.5);
+  test.equal(scale.scaleLinear().domain([2, 1]).range([0, 0]).invert(1), 1.5);
   test.end();
 });
 

diff --git a/test/pow-test.js b/test/pow-test.js
@@ -31,9 +31,9 @@ tape("pow(x) ignores extra domain values if the range is smaller than the domain
   test.end();
 });
 
-tape("pow(x) maps an empty domain to the range start", function(test) {
-  test.equal(scale.scalePow().domain([0, 0]).range([1, 2])(0), 1);
-  test.equal(scale.scalePow().domain([0, 0]).range([2, 1])(1), 2);
+tape("pow(x) maps an empty domain to the middle of the range", function(test) {
+  test.equal(scale.scalePow().domain([0, 0]).range([1, 2])(0), 1.5);
+  test.equal(scale.scalePow().domain([0, 0]).range([2, 1])(1), 1.5);
   test.end();
 });
 
@@ -77,9 +77,9 @@ tape("pow.invert(y) maps a range value y to a domain value x", function(test) {
   test.end();
 });
 
-tape("pow.invert(y) maps an empty range to the domain start", function(test) {
-  test.equal(scale.scalePow().domain([1, 2]).range([0, 0]).invert(0), 1);
-  test.equal(scale.scalePow().domain([2, 1]).range([0, 0]).invert(1), 2);
+tape("pow.invert(y) maps an empty range to the middle of the domain", function(test) {
+  test.equal(scale.scalePow().domain([1, 2]).range([0, 0]).invert(0), 1.5);
+  test.equal(scale.scalePow().domain([2, 1]).range([0, 0]).invert(1), 1.5);
   test.end();
 });