107 lines
7.0 KiB
Markdown
107 lines
7.0 KiB
Markdown
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---
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id: 587d7fab367417b2b2512bd8
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title: Add Attributes to the Circle 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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videoUrl: ''
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localeTitle: 将属性添加到圆形元素
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---
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## Description
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<section id="description">最后一项挑战为<code>dataset</code>每个点创建了<code>circle</code>元素，并将它们附加到SVG画布。但D3需要更多关于每个<code>circle</code>的位置和大小的信息才能正确显示它们。 SVG中的<code>circle</code>有三个主要属性。 <code>cx</code>和<code>cy</code>属性是坐标。它们告诉D3在SVG画布上定位形状<em>中心</em>的位置。半径（ <code>r</code>属性）给出<code>circle</code>的大小。就像<code>rect</code> <code>y</code>坐标一样， <code>circle</code>的<code>cy</code>属性是从SVG画布的顶部测量的，而不是从底部测量的。所有这三个属性都可以使用回调函数动态设置其值。请记住，后链接的所有方法<code>data(dataset)</code>每个项目在运行一次<code>dataset</code> 。回调函数中的<code>d</code>参数指的是<code>dataset</code>的当前项，它是每个点的数组。您可以使用括号表示法（如<code>d[0]</code> ）来访问该数组中的值。 </section>
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## Instructions
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<section id="instructions">将<code>cx</code> ， <code>cy</code>和<code>r</code>属性添加到<code>circle</code>元素。在<code>cx</code>值应为阵列中的每个项目中的第一个数字<code>dataset</code> 。 <code>cy</code>值应基于数组中的第二个数字，但请确保图表正面向上显示而不是反转。所有圈子的<code>r</code>值应为5。 </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: 您的代码应该有10个<code>circle</code>元素。
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testString: 'assert($("circle").length == 10, "Your code should have 10 <code>circle</code> elements.");'
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- text: 第一个<code>circle</code>元素的<code>cx</code>值应为34， <code>cy</code>值为422， <code>r</code>值为5。
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testString: 'assert($("circle").eq(0).attr("cx") == "34" && $("circle").eq(0).attr("cy") == "422" && $("circle").eq(0).attr("r") == "5", "The first <code>circle</code> element should have a <code>cx</code> value of 34, a <code>cy</code> value of 422, and an <code>r</code> value of 5.");'
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- text: 第二个<code>circle</code>元素的<code>cx</code>值应为109， <code>cy</code>值为220， <code>r</code>值为5。
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testString: 'assert($("circle").eq(1).attr("cx") == "109" && $("circle").eq(1).attr("cy") == "220" && $("circle").eq(1).attr("r") == "5", "The second <code>circle</code> element should have a <code>cx</code> value of 109, a <code>cy</code> value of 220, and an <code>r</code> value of 5.");'
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- text: 第三个<code>circle</code>元素的<code>cx</code>值应为310， <code>cy</code>值为380， <code>r</code>值为5。
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testString: 'assert($("circle").eq(2).attr("cx") == "310" && $("circle").eq(2).attr("cy") == "380" && $("circle").eq(2).attr("r") == "5", "The third <code>circle</code> element should have a <code>cx</code> value of 310, a <code>cy</code> value of 380, and an <code>r</code> value of 5.");'
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- text: 第四个<code>circle</code>元素的<code>cx</code>值应为79， <code>cy</code>值为89， <code>r</code>值为5。
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testString: 'assert($("circle").eq(3).attr("cx") == "79" && $("circle").eq(3).attr("cy") == "89" && $("circle").eq(3).attr("r") == "5", "The fourth <code>circle</code> element should have a <code>cx</code> value of 79, a <code>cy</code> value of 89, and an <code>r</code> value of 5.");'
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- text: 第五个<code>circle</code>元素的<code>cx</code>值应为420， <code>cy</code>值为280， <code>r</code>值为5。
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testString: 'assert($("circle").eq(4).attr("cx") == "420" && $("circle").eq(4).attr("cy") == "280" && $("circle").eq(4).attr("r") == "5", "The fifth <code>circle</code> element should have a <code>cx</code> value of 420, a <code>cy</code> value of 280, and an <code>r</code> value of 5.");'
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- text: 第六个<code>circle</code>元素的<code>cx</code>值应为233， <code>cy</code>值为355， <code>r</code>值为5。
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testString: 'assert($("circle").eq(5).attr("cx") == "233" && $("circle").eq(5).attr("cy") == "355" && $("circle").eq(5).attr("r") == "5", "The sixth <code>circle</code> element should have a <code>cx</code> value of 233, a <code>cy</code> value of 355, and an <code>r</code> value of 5.");'
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- text: 第七个<code>circle</code>元素的<code>cx</code>值应为333， <code>cy</code>值为404， <code>r</code>值为5。
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testString: 'assert($("circle").eq(6).attr("cx") == "333" && $("circle").eq(6).attr("cy") == "404" && $("circle").eq(6).attr("r") == "5", "The seventh <code>circle</code> element should have a <code>cx</code> value of 333, a <code>cy</code> value of 404, and an <code>r</code> value of 5.");'
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- text: 第八个<code>circle</code>元素的<code>cx</code>值应为222， <code>cy</code>值为167， <code>r</code>值为5。
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testString: 'assert($("circle").eq(7).attr("cx") == "222" && $("circle").eq(7).attr("cy") == "167" && $("circle").eq(7).attr("r") == "5", "The eighth <code>circle</code> element should have a <code>cx</code> value of 222, a <code>cy</code> value of 167, and an <code>r</code> value of 5.");'
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- text: 第九个<code>circle</code>元素的<code>cx</code>值应为78， <code>cy</code>值为180， <code>r</code>值为5。
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testString: 'assert($("circle").eq(8).attr("cx") == "78" && $("circle").eq(8).attr("cy") == "180" && $("circle").eq(8).attr("r") == "5", "The ninth <code>circle</code> element should have a <code>cx</code> value of 78, a <code>cy</code> value of 180, and an <code>r</code> value of 5.");'
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- text: 第十个<code>circle</code>元素的<code>cx</code>值应为21， <code>cy</code>值为377， <code>r</code>值为5。
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testString: 'assert($("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.");'
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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 = [
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[ 34, 78 ],
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[ 109, 280 ],
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[ 310, 120 ],
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[ 79, 411 ],
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[ 420, 220 ],
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[ 233, 145 ],
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[ 333, 96 ],
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[ 222, 333 ],
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[ 78, 320 ],
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[ 21, 123 ]
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];
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const w = 500;
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const h = 500;
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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("circle")
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.data(dataset)
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.enter()
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.append("circle")
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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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