fix tickFormat on a collapsed domain (start == end)

closes #286 closes observablehq/plot#2076
d3 · Jun 17, 2024 · ddfa33e · ddfa33e
1 parent d6904a4
commit ddfa33e
Show file tree

Hide file tree

Showing 2 changed files with 26 additions and 3 deletions.
diff --git a/src/tickFormat.js b/src/tickFormat.js
@@ -1,10 +1,10 @@
 import {tickStep} from "d3-array";
 import {format, formatPrefix, formatSpecifier, precisionFixed, precisionPrefix, precisionRound} from "d3-format";
 
-export default function tickFormat(start, stop, count, specifier) {
+export default function tickFormat(start, stop, count, specifierIn) {
  var step = tickStep(start, stop, count),
  precision;
- specifier = formatSpecifier(specifier == null ? ",f" : specifier);
+ const specifier = formatSpecifier(specifierIn == null ? ",f" : specifierIn);
  switch (specifier.type) {
  case "s": {
  var value = Math.max(Math.abs(start), Math.abs(stop));
@@ -21,7 +21,14 @@ export default function tickFormat(start, stop, count, specifier) {
  }
  case "f":
  case "%": {
- if (specifier.precision == null && !isNaN(precision = precisionFixed(step))) specifier.precision = precision - (specifier.type === "%") * 2;
+ if (specifier.precision == null) {
+ if (step === 0) {
+ if (specifierIn == null) specifier.trim = true;
+ }
+ else if (!isNaN(precision = precisionFixed(step))) {
+ specifier.precision = precision - (specifier.type === "%") * 2;
+ }
+ } 
  break;
  }
  }

diff --git a/test/tickFormat-test.js b/test/tickFormat-test.js
@@ -40,4 +40,20 @@ it("tickFormat(start, stop, count) uses the default precision when the domain is
  const f = tickFormat(0, NaN, 10);
  assert.strictEqual(f + "", " >-,f");
  assert.strictEqual(f(0.12), "0.120000");
+
+ const f2 = tickFormat(0.12, NaN, 10);
+ assert.strictEqual(f2 + "", " >-,f");
+ assert.strictEqual(f2(0.12), "0.120000");
+});
+
+it("tickFormat(start, stop, count) uses the default precision with trimming when the domain is collapsed", () => {
+ const f = tickFormat(5.5, 5.5, 10);
+ assert.strictEqual(f + "", " >-,~f");
+ assert.strictEqual(f(0), "0");
+ assert.strictEqual(f(5.5), "5.5");
+ assert.strictEqual(f(Math.PI), "3.141593");
+ assert.strictEqual(f(-Math.PI), "−3.141593");
+ assert.strictEqual(f(Math.PI * 1e7), "31,415,926.535898");
+ assert.strictEqual(f(-Math.PI * 1e7), "−31,415,926.535898");
 });
+