104 lines
5.0 KiB
Markdown
104 lines
5.0 KiB
Markdown
---
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id: 587d7faa367417b2b2512bd2
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title: Add Labels to D3 Elements
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required:
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- src: 'https://cdnjs.cloudflare.com/ajax/libs/d3/4.3.0/d3.min.js'
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challengeType: 6
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---
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## Description
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<section id='description'>
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D3 lets you label a graph element, such as a bar, using the SVG <code>text</code> element.
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Like the <code>rect</code> element, a <code>text</code> element needs to have <code>x</code> and <code>y</code> attributes, to place it on the SVG canvas. It also needs to access the data to display those values.
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D3 gives you a high level of control over how you label your bars.
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</section>
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## Instructions
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<section id='instructions'>
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The code in the editor already binds the data to each new <code>text</code> element. First, append <code>text</code> nodes to the <code>svg</code>. Next, add attributes for the <code>x</code> and <code>y</code> coordinates. They should be calculated the same way as the <code>rect</code> ones, except the <code>y</code> value for the <code>text</code> should make the label sit 3 units higher than the bar. Finally, use the D3 <code>text()</code> method to set the label equal to the data point value.
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<strong>Note</strong><br>For the label to sit higher than the bar, decide if the <code>y</code> value for the <code>text</code> should be 3 greater or 3 less than the <code>y</code> value for the bar.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: The first <code>text</code> element should have a label of 12 and a <code>y</code> value of 61.
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testString: 'assert($(''text'').eq(0).text() == ''12'' && $(''text'').eq(0).attr(''y'') == ''61'', ''The first <code>text</code> element should have a label of 12 and a <code>y</code> value of 61.'');'
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- text: The second <code>text</code> element should have a label of 31 and a <code>y</code> value of 4.
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testString: 'assert($(''text'').eq(1).text() == ''31'' && $(''text'').eq(1).attr(''y'') == ''4'', ''The second <code>text</code> element should have a label of 31 and a <code>y</code> value of 4.'');'
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- text: The third <code>text</code> element should have a label of 22 and a <code>y</code> value of 31.
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testString: 'assert($(''text'').eq(2).text() == ''22'' && $(''text'').eq(2).attr(''y'') == ''31'', ''The third <code>text</code> element should have a label of 22 and a <code>y</code> value of 31.'');'
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- text: The fourth <code>text</code> element should have a label of 17 and a <code>y</code> value of 46.
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testString: 'assert($(''text'').eq(3).text() == ''17'' && $(''text'').eq(3).attr(''y'') == ''46'', ''The fourth <code>text</code> element should have a label of 17 and a <code>y</code> value of 46.'');'
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- text: The fifth <code>text</code> element should have a label of 25 and a <code>y</code> value of 22.
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testString: 'assert($(''text'').eq(4).text() == ''25'' && $(''text'').eq(4).attr(''y'') == ''22'', ''The fifth <code>text</code> element should have a label of 25 and a <code>y</code> value of 22.'');'
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- text: The sixth <code>text</code> element should have a label of 18 and a <code>y</code> value of 43.
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testString: 'assert($(''text'').eq(5).text() == ''18'' && $(''text'').eq(5).attr(''y'') == ''43'', ''The sixth <code>text</code> element should have a label of 18 and a <code>y</code> value of 43.'');'
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- text: The seventh <code>text</code> element should have a label of 29 and a <code>y</code> value of 10.
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testString: 'assert($(''text'').eq(6).text() == ''29'' && $(''text'').eq(6).attr(''y'') == ''10'', ''The seventh <code>text</code> element should have a label of 29 and a <code>y</code> value of 10.'');'
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- text: The eighth <code>text</code> element should have a label of 14 and a <code>y</code> value of 55.
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testString: 'assert($(''text'').eq(7).text() == ''14'' && $(''text'').eq(7).attr(''y'') == ''55'', ''The eighth <code>text</code> element should have a label of 14 and a <code>y</code> value of 55.'');'
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- text: The ninth <code>text</code> element should have a label of 9 and a <code>y</code> value of 70.
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testString: 'assert($(''text'').eq(8).text() == ''9'' && $(''text'').eq(8).attr(''y'') == ''70'', ''The ninth <code>text</code> element should have a label of 9 and a <code>y</code> value of 70.'');'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='html-seed'>
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```html
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<body>
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<script>
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const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];
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const w = 500;
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const h = 100;
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const svg = d3.select("body")
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.append("svg")
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.attr("width", w)
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.attr("height", h);
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svg.selectAll("rect")
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.data(dataset)
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.enter()
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.append("rect")
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.attr("x", (d, i) => i * 30)
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.attr("y", (d, i) => h - 3 * d)
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.attr("width", 25)
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.attr("height", (d, i) => 3 * d)
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.attr("fill", "navy");
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svg.selectAll("text")
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.data(dataset)
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.enter()
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// Add your code below this line
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// Add your code above this line
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</script>
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<body>
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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