2018-10-10 18:03:03 -04:00
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---
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id: 587d7fa9367417b2b2512bcf
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title: Dynamically Change the Height of Each Bar
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challengeType: 6
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videoUrl: ''
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localeTitle: 动态改变每个栏的高度
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---
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## Description
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<section id="description">每个条的高度可以设置为数组中数据点的值，类似于动态设置<code>x</code>值的方式。 <blockquote> selection.attr（“property”，（d，i）=> { <br> / * <br> * d是数据点值<br> * i是数组中数据点的索引<br> * / <br> }） </blockquote></section>
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## Instructions
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<section id="instructions">更改<code>height</code>属性的回调函数以返回数据值乘以3. <strong>注意</strong> <br>请记住，将所有数据点乘以相同的常量可以缩放数据（如放大）。在此示例中，有助于查看条形值之间的差异。 </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: 第一个<code>rect</code>的<code>height</code>应为36。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(0).attr('height') == '36');
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- text: 第二个<code>rect</code>的<code>height</code>应为93。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(1).attr('height') == '93');
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2018-10-10 18:03:03 -04:00
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- text: 第三个<code>rect</code>的<code>height</code>应为66。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(2).attr('height') == '66');
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- text: 第四个<code>rect</code>的<code>height</code>应为51。
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testString: assert($('rect').eq(3).attr('height') == '51');
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- text: 第五个<code>rect</code>的<code>height</code>应为75。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(4).attr('height') == '75');
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- text: 第六个<code>rect</code>的<code>height</code>应为54。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(5).attr('height') == '54');
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- text: 第七个<code>rect</code>的<code>height</code>应为87。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(6).attr('height') == '87');
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- text: 第八个<code>rect</code>应该有42的<code>height</code> 。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(7).attr('height') == '42');
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- text: 第九个<code>rect</code>的<code>height</code>应为27。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').eq(8).attr('height') == '27');
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2018-10-10 18:03:03 -04:00
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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", 0)
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.attr("width", 25)
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.attr("height", (d, i) => {
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// Add your code below this line
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// Add your code above this line
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});
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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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2020-08-13 17:24:35 +02:00
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/section>
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