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Fix generateTicks when working with tiny numbers #5948

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Merged
merged 9 commits into from
Jan 9, 2019
Merged

Fix generateTicks when working with tiny numbers #5948

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79b261f
increase spacing until there is a range
kurkle Jan 1, 2019
fe1c1f3
add comment
kurkle Jan 1, 2019
6a43dfa
extra newline removed
kurkle Jan 3, 2019
f6c9fa7
2 points is enough
kurkle Jan 3, 2019
e70c334
save a line
kurkle Jan 3, 2019
48314ed
another solution
kurkle Jan 3, 2019
dbfe1b5
use variables instead of changing dataRange,apply a lower bound to sp…
kurkle Jan 3, 2019
363c295
spacing < MIN_SPACING
kurkle Jan 4, 2019
ef226c7
requested changes
kurkle Jan 6, 2019
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32 changes: 20 additions & 12 deletions src/scales/scale.linearbase.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ var helpers = require('../helpers/index');
var Scale = require('../core/core.scale');

var noop = helpers.noop;
var isNullOrUndef = helpers.isNullOrUndef;

/**
* Generate a set of linear ticks
Expand All @@ -17,24 +18,31 @@ function generateTicks(generationOptions, dataRange) {
// "nice number" algorithm. See https://stackoverflow.com/questions/8506881/nice-label-algorithm-for-charts-with-minimum-ticks
// for details.

var MIN_SPACING = 1e-14;
var stepSize = generationOptions.stepSize;
var unit = stepSize || 1;
var maxNumSpaces = generationOptions.maxTicks - 1;
var min = generationOptions.min;
var max = generationOptions.max;
var precision = generationOptions.precision;
var spacing, factor, niceMin, niceMax, numSpaces;
var rmin = dataRange.min;
var rmax = dataRange.max;
var spacing = helpers.niceNum((rmax - rmin) / maxNumSpaces / unit) * unit;
var factor, niceMin, niceMax, numSpaces;

// Beyond MIN_SPACING floating point numbers being to lose precision
// such that we can't do the math necessary to generate ticks
if (spacing < MIN_SPACING && isNullOrUndef(min) && isNullOrUndef(max)) {
return [rmin, rmax];
}

// spacing is set to a nice number of the dataRange divided by maxNumSpaces.
// stepSize is used as a minimum unit if it is specified.
spacing = helpers.niceNum((dataRange.max - dataRange.min) / maxNumSpaces / unit) * unit;
numSpaces = Math.ceil(dataRange.max / spacing) - Math.floor(dataRange.min / spacing);
numSpaces = Math.ceil(rmax / spacing) - Math.floor(rmin / spacing);
if (numSpaces > maxNumSpaces) {
// If the calculated num of spaces exceeds maxNumSpaces, recalculate it
spacing = helpers.niceNum(numSpaces * spacing / maxNumSpaces / unit) * unit;
}

if (stepSize || helpers.isNullOrUndef(precision)) {
if (stepSize || isNullOrUndef(precision)) {
// If a precision is not specified, calculate factor based on spacing
factor = Math.pow(10, helpers.decimalPlaces(spacing));
} else {
Expand All @@ -43,16 +51,16 @@ function generateTicks(generationOptions, dataRange) {
spacing = Math.ceil(spacing * factor) / factor;
}

niceMin = Math.floor(dataRange.min / spacing) * spacing;
niceMax = Math.ceil(dataRange.max / spacing) * spacing;
niceMin = Math.floor(rmin / spacing) * spacing;
niceMax = Math.ceil(rmax / spacing) * spacing;

// If min, max and stepSize is set and they make an evenly spaced scale use it.
if (stepSize) {
// If very close to our whole number, use it.
if (!helpers.isNullOrUndef(min) && helpers.almostWhole(min / spacing, spacing / 1000)) {
if (!isNullOrUndef(min) && helpers.almostWhole(min / spacing, spacing / 1000)) {
niceMin = min;
}
if (!helpers.isNullOrUndef(max) && helpers.almostWhole(max / spacing, spacing / 1000)) {
if (!isNullOrUndef(max) && helpers.almostWhole(max / spacing, spacing / 1000)) {
niceMax = max;
}
}
Expand All @@ -67,11 +75,11 @@ function generateTicks(generationOptions, dataRange) {

niceMin = Math.round(niceMin * factor) / factor;
niceMax = Math.round(niceMax * factor) / factor;
ticks.push(helpers.isNullOrUndef(min) ? niceMin : min);
ticks.push(isNullOrUndef(min) ? niceMin : min);
for (var j = 1; j < numSpaces; ++j) {
ticks.push(Math.round((niceMin + j * spacing) * factor) / factor);
}
ticks.push(helpers.isNullOrUndef(max) ? niceMax : max);
ticks.push(isNullOrUndef(max) ? niceMax : max);

return ticks;
}
Expand Down
25 changes: 25 additions & 0 deletions test/specs/scale.linear.tests.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1170,4 +1170,29 @@ describe('Linear Scale', function() {
expect(data[0]._model.base + minBarLength).toEqual(data[0]._model.x);
expect(data[1]._model.base - minBarLength).toEqual(data[1]._model.x);
});

it('Should generate max and min that are not equal when data contains values that are very close to each other', function() {
var chart = window.acquireChart({
type: 'scatter',
data: {
datasets: [{
data: [
{x: 1, y: 1.8548483304974972},
{x: 2, y: 1.8548483304974974},
]
}],
},
options: {
scales: {
yAxes: [{
id: 'yScale0',
type: 'linear',
}]
}
}
});

expect(chart.scales.yScale0).not.toEqual(undefined); // must construct
expect(chart.scales.yScale0.max).toBeGreaterThan(chart.scales.yScale0.min);
});
});