freeCodeCamp/curriculum/challenges/english/04-data-visualization/data-visualization-with-d3/add-attributes-to-the-circle-elements.english.md

---
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>