111 lines
7.4 KiB
Markdown
111 lines
7.4 KiB
Markdown
---
|
|
id: 587d7fab367417b2b2512bd8
|
|
title: Add Attributes to the Circle Elements
|
|
required:
|
|
- src: 'https://cdnjs.cloudflare.com/ajax/libs/d3/4.3.0/d3.min.js'
|
|
challengeType: 6
|
|
---
|
|
|
|
## Description
|
|
<section id='description'>
|
|
The last challenge created the <code>circle</code> elements for each point in the <code>dataset</code>, and appended them to the SVG canvas. But D3 needs more information about the position and size of each <code>circle</code> to display them correctly.
|
|
A <code>circle</code> in SVG has three main attributes. The <code>cx</code> and <code>cy</code> attributes are the coordinates. They tell D3 where to position the <em>center</em> of the shape on the SVG canvas. The radius (<code>r</code> attribute) gives the size of the <code>circle</code>.
|
|
Just like the <code>rect</code> <code>y</code> coordinate, the <code>cy</code> attribute for a <code>circle</code> is measured from the top of the SVG canvas, not from the bottom.
|
|
All three attributes can use a callback function to set their values dynamically. Remember that all methods chained after <code>data(dataset)</code> run once per item in <code>dataset</code>. The <code>d</code> parameter in the callback function refers to the current item in <code>dataset</code>, which is an array for each point. You use bracket notation, like <code>d[0]</code>, to access the values in that array.
|
|
</section>
|
|
|
|
## Instructions
|
|
<section id='instructions'>
|
|
Add <code>cx</code>, <code>cy</code>, and <code>r</code> attributes to the <code>circle</code> elements. The <code>cx</code> value should be the first number in the array for each item in <code>dataset</code>. The <code>cy</code> value should be based off the second number in the array, but make sure to show the chart right-side-up and not inverted. The <code>r</code> value should be 5 for all circles.
|
|
</section>
|
|
|
|
## Tests
|
|
<section id='tests'>
|
|
|
|
```yml
|
|
tests:
|
|
- text: Your code should have 10 <code>circle</code> elements.
|
|
testString: assert($('circle').length == 10, 'Your code should have 10 <code>circle</code> elements.');
|
|
- text: The first <code>circle</code> element should have a <code>cx</code> value of 34, a <code>cy</code> value of 422, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(0).attr('cx') == '34' && $('circle').eq(0).attr('cy') == '422' && $('circle').eq(0).attr('r') == '5', 'The first <code>circle</code> element should have a <code>cx</code> value of 34, a <code>cy</code> value of 422, and an <code>r</code> value of 5.');
|
|
- text: The second <code>circle</code> element should have a <code>cx</code> value of 109, a <code>cy</code> value of 220, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(1).attr('cx') == '109' && $('circle').eq(1).attr('cy') == '220' && $('circle').eq(1).attr('r') == '5', 'The second <code>circle</code> element should have a <code>cx</code> value of 109, a <code>cy</code> value of 220, and an <code>r</code> value of 5.');
|
|
- text: The third <code>circle</code> element should have a <code>cx</code> value of 310, a <code>cy</code> value of 380, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(2).attr('cx') == '310' && $('circle').eq(2).attr('cy') == '380' && $('circle').eq(2).attr('r') == '5', 'The third <code>circle</code> element should have a <code>cx</code> value of 310, a <code>cy</code> value of 380, and an <code>r</code> value of 5.');
|
|
- text: The fourth <code>circle</code> element should have a <code>cx</code> value of 79, a <code>cy</code> value of 89, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(3).attr('cx') == '79' && $('circle').eq(3).attr('cy') == '89' && $('circle').eq(3).attr('r') == '5', 'The fourth <code>circle</code> element should have a <code>cx</code> value of 79, a <code>cy</code> value of 89, and an <code>r</code> value of 5.');
|
|
- text: The fifth <code>circle</code> element should have a <code>cx</code> value of 420, a <code>cy</code> value of 280, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(4).attr('cx') == '420' && $('circle').eq(4).attr('cy') == '280' && $('circle').eq(4).attr('r') == '5', 'The fifth <code>circle</code> element should have a <code>cx</code> value of 420, a <code>cy</code> value of 280, and an <code>r</code> value of 5.');
|
|
- text: The sixth <code>circle</code> element should have a <code>cx</code> value of 233, a <code>cy</code> value of 355, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(5).attr('cx') == '233' && $('circle').eq(5).attr('cy') == '355' && $('circle').eq(5).attr('r') == '5', 'The sixth <code>circle</code> element should have a <code>cx</code> value of 233, a <code>cy</code> value of 355, and an <code>r</code> value of 5.');
|
|
- text: The seventh <code>circle</code> element should have a <code>cx</code> value of 333, a <code>cy</code> value of 404, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(6).attr('cx') == '333' && $('circle').eq(6).attr('cy') == '404' && $('circle').eq(6).attr('r') == '5', 'The seventh <code>circle</code> element should have a <code>cx</code> value of 333, a <code>cy</code> value of 404, and an <code>r</code> value of 5.');
|
|
- text: The eighth <code>circle</code> element should have a <code>cx</code> value of 222, a <code>cy</code> value of 167, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(7).attr('cx') == '222' && $('circle').eq(7).attr('cy') == '167' && $('circle').eq(7).attr('r') == '5', 'The eighth <code>circle</code> element should have a <code>cx</code> value of 222, a <code>cy</code> value of 167, and an <code>r</code> value of 5.');
|
|
- text: The ninth <code>circle</code> element should have a <code>cx</code> value of 78, a <code>cy</code> value of 180, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(8).attr('cx') == '78' && $('circle').eq(8).attr('cy') == '180' && $('circle').eq(8).attr('r') == '5', 'The ninth <code>circle</code> element should have a <code>cx</code> value of 78, a <code>cy</code> value of 180, and an <code>r</code> value of 5.');
|
|
- text: The tenth <code>circle</code> element should have a <code>cx</code> value of 21, a <code>cy</code> value of 377, and an <code>r</code> value of 5.
|
|
testString: assert($('circle').eq(9).attr('cx') == '21' && $('circle').eq(9).attr('cy') == '377' && $('circle').eq(9).attr('r') == '5', 'The tenth <code>circle</code> element should have a <code>cx</code> value of 21, a <code>cy</code> value of 377, and an <code>r</code> value of 5.');
|
|
|
|
```
|
|
|
|
</section>
|
|
|
|
## Challenge Seed
|
|
<section id='challengeSeed'>
|
|
|
|
<div id='html-seed'>
|
|
|
|
```html
|
|
<body>
|
|
<script>
|
|
const dataset = [
|
|
[ 34, 78 ],
|
|
[ 109, 280 ],
|
|
[ 310, 120 ],
|
|
[ 79, 411 ],
|
|
[ 420, 220 ],
|
|
[ 233, 145 ],
|
|
[ 333, 96 ],
|
|
[ 222, 333 ],
|
|
[ 78, 320 ],
|
|
[ 21, 123 ]
|
|
];
|
|
|
|
|
|
const w = 500;
|
|
const h = 500;
|
|
|
|
const svg = d3.select("body")
|
|
.append("svg")
|
|
.attr("width", w)
|
|
.attr("height", h);
|
|
|
|
svg.selectAll("circle")
|
|
.data(dataset)
|
|
.enter()
|
|
.append("circle")
|
|
// Add your code below this line
|
|
|
|
|
|
|
|
// Add your code above this line
|
|
|
|
</script>
|
|
</body>
|
|
```
|
|
|
|
</div>
|
|
|
|
|
|
|
|
</section>
|
|
|
|
## Solution
|
|
<section id='solution'>
|
|
|
|
```js
|
|
// solution required
|
|
```
|
|
</section>
|