146 lines
2.9 KiB
Markdown
146 lines
2.9 KiB
Markdown
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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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forumTopicId: 301486
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dashedName: dynamically-change-the-height-of-each-bar
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---
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# --description--
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The height of each bar can be set to the value of the data point in the array, similar to how the `x` value was set dynamically.
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```js
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selection.attr("property", (d, i) => {
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})
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```
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Here `d` would be the data point value, and `i` would be the index of the data point in the array.
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# --instructions--
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Change the callback function for the `height` attribute to return the data value times 3.
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**Note:** Remember that multiplying all data points by the same constant scales the data (like zooming in). It helps to see the differences between bar values in this example.
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# --hints--
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The first `rect` should have a `height` of `36`.
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```js
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assert($('rect').eq(0).attr('height') == '36');
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```
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The second `rect` should have a `height` of `93`.
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```js
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assert($('rect').eq(1).attr('height') == '93');
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```
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The third `rect` should have a `height` of `66`.
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```js
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assert($('rect').eq(2).attr('height') == '66');
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```
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The fourth `rect` should have a `height` of `51`.
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```js
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assert($('rect').eq(3).attr('height') == '51');
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```
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The fifth `rect` should have a `height` of `75`.
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```js
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assert($('rect').eq(4).attr('height') == '75');
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```
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The sixth `rect` should have a `height` of `54`.
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```js
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assert($('rect').eq(5).attr('height') == '54');
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```
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The seventh `rect` should have a `height` of `87`.
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```js
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assert($('rect').eq(6).attr('height') == '87');
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```
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The eighth `rect` should have a `height` of `42`.
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```js
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assert($('rect').eq(7).attr('height') == '42');
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```
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The ninth `rect` should have a `height` of `27`.
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```js
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assert($('rect').eq(8).attr('height') == '27');
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```
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# --seed--
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## --seed-contents--
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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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# --solutions--
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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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return d * 3
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});
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</script>
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</body>
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```
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