80 lines
3.2 KiB
Markdown
80 lines
3.2 KiB
Markdown
|
---
|
||
|
|
id: 587d7fac367417b2b2512bdb
|
||
|
|
title: Set a Domain and a Range on a Scale
|
||
|
|
required:
|
||
|
|
- src: 'https://cdnjs.cloudflare.com/ajax/libs/d3/4.3.0/d3.min.js'
|
||
|
|
challengeType: 6
|
||
|
|
---
|
||
|
|
|
||
|
|
## Description
|
||
|
|
<section id='description'>
|
||
|
|
By default, scales use the identity relationship - the input value maps to the output value. But scales can be much more flexible and interesting.
|
||
|
|
Say a data set has values ranging from 50 to 480. This is the input information for a scale, and is also known as the domain.
|
||
|
|
You want to map those points along the <code>x</code> axis on the SVG canvas, between 10 units and 500 units. This is the output information, which is also known as the range.
|
||
|
|
The <code>domain()</code> and <code>range()</code> methods set these values for the scale. Both methods take an array of at least two elements as an argument. Here's an example:
|
||
|
|
<blockquote>// Set a domain<br>// The domain covers the set of input values<br>scale.domain([50, 480]);<br>// Set a range<br>// The range covers the set of output values<br>scale.range([10, 500]);<br>scale(50) // Returns 10<br>scale(480) // Returns 500<br>scale(325) // Returns 323.37<br>scale(750) // Returns 807.67<br>d3.scaleLinear()</blockquote>
|
||
|
|
Notice that the scale uses the linear relationship between the domain and range values to figure out what the output should be for a given number. The minimum value in the domain (50) maps to the minimum value (10) in the range.
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Instructions
|
||
|
|
<section id='instructions'>
|
||
|
|
Create a scale and set its domain to <code>[250, 500]</code> and range to <code>[10, 150]</code>.
|
||
|
|
<strong>Note</strong><br>You can chain the <code>domain()</code> and <code>range()</code> methods onto the <code>scale</code> variable.
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Tests
|
||
|
|
<section id='tests'>
|
||
|
|
|
||
|
|
```yml
|
||
|
|
tests:
|
||
|
|
- text: Your code should use the <code>domain()</code> method.
|
||
|
|
testString: 'assert(code.match(/\.domain/g), ''Your code should use the <code>domain()</code> method.'');'
|
||
|
|
- text: 'The <code>domain()</code> of the scale should be set to <code>[250, 500]</code>.'
|
||
|
|
testString: 'assert(JSON.stringify(scale.domain()) == JSON.stringify([250, 500]), ''The <code>domain()</code> of the scale should be set to <code>[250, 500]</code>.'');'
|
||
|
|
- text: Your code should use the <code>range()</code> method.
|
||
|
|
testString: 'assert(code.match(/\.range/g), ''Your code should use the <code>range()</code> method.'');'
|
||
|
|
- text: 'The <code>range()</code> of the scale should be set to <code>[10, 150]</code>.'
|
||
|
|
testString: 'assert(JSON.stringify(scale.range()) == JSON.stringify([10, 150]), ''The <code>range()</code> of the scale should be set to <code>[10, 150]</code>.'');'
|
||
|
|
- text: The text in the <code>h2</code> should be -102.
|
||
|
|
testString: 'assert($(''h2'').text() == ''-102'', ''The text in the <code>h2</code> should be -102.'');'
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Challenge Seed
|
||
|
|
<section id='challengeSeed'>
|
||
|
|
|
||
|
|
<div id='html-seed'>
|
||
|
|
|
||
|
|
```html
|
||
|
|
<body>
|
||
|
|
<script>
|
||
|
|
// Add your code below this line
|
||
|
|
const scale = d3.scaleLinear();
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
// Add your code above this line
|
||
|
|
const output = scale(50);
|
||
|
|
d3.select("body")
|
||
|
|
.append("h2")
|
||
|
|
.text(output);
|
||
|
|
</script>
|
||
|
|
</body>
|
||
|
|
```
|
||
|
|
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Solution
|
||
|
|
<section id='solution'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
// solution required
|
||
|
|
```
|
||
|
|
</section>
|