Day 40, 2020-10-03Day 37&38&39, 2020-09-30 & 2020-10-01 & 2020-10-02Day 35 & Day 36, 2020-09-28 & 2020-09-29Day 34, 2020-09-27Day 33, 2020-09-26Day 32 (Task 10), 2020-09-25Day 31 (9-2-10), 2020-09-24Day Thirty (A puzzle to be solved), 2020-09-22Day Twenty Nine, 2020-09-22Day Twenty-Eight (Task 9-2-9), 2020-09-21Day Twenty-Seven, 2020-09-20Day Twenty Six, 2020-09-19Day Twenty Five, 2020-09-18Day Twenty Four, 2020-09-17Day Twenty Three (Task 9-2), 2020-09-16Day Twenty Two (Task 9-1 continued), 2020-09-15Day Twenty-One (Task 9-1 continued), 2020-09-14Day Twenty (Task 8 Continued + Task 9-1), 2020-09-13Day Nineteen (Task 8), Spet. 12, 2020Day Eighteen (Task 7-1-10, 11, Sept. 11, 2020Day Fourteen, Fifteen, Sixteen & Seventeen, Spet. 07 ~ 10, 2020Day Thirteen (Task 7-1), 2020-09-06Day Twelve, Sept. 5, 2020: ScalesDay Eleven, Sept.4th, 2020Day Nine, 2020-09-02Day Eight, Spet. 1, 2020Day Six, 30 Aug 2020Day Five, 29 Aug 2020Day Four, 28 Aug 2020Day Three, 27 Aug 2020Day 1 & Day 2, 25 Aug. & 26 Aug., 2020, Basic Commands
Day Ten (Task 6-6), Sept. 3rd, 2020
md`# Day Ten (Task 6-6), Sept. 3rd, 2020`
d3 = require("d3@6")
md`## Task 6-1
- 6-1-1. Again, I forgot the difference between \`.attr()\` and \`.style()\`.
- \`.style()\` assigns **CSS styles (properties and value)s** to **a HTML element**, just like the way we assign CSS styles when we are writing HTML. For example, \`<div style="height: 75px;"></div>\`.
- In comparison, \`.attr()\` sets **an HTML attribute and its values** on a HTML element. Note that an element's class is stored as an HTML atrribute.
- 6-1-3. \`A.push(B)\` will put B to the end of A. \`.push()\` is an array method.
`
md`## Task 6-2
- 6-2-2.
- \`<svg>\` is just like an HTML element. \`width\`, \`height\` are its attributs. \`rect\`, \`circle\`, \`text\` are all elements. \`x\`, \`y\`, \`cx\`, \`cy\` and \`r\` are all attributs. Read [this amazing tutorial](http://jonathansoma.com/tutorials/d3/using-attr-and-style/) to really understant what is an element and what are attributs.
- **I still did not understand it. Why is that I need to use \`style()\` to specify the \`height\` of \`div\` in **Task 6-1-1** but I need to use \`.attr()\` to specify the \`height\` of a \`svg\` here??** I guess it's because that for \`div\`, \`height\` is a CSS property, but for \`svg\`, \`height\` is an attribute? Maybe.
- 6-2-4. I need to use \`svg.selectAll('circle')\` rather than \`svg.select('circle')\`. Think about why for a moment;
- 6-2-5. As the [amazing tutorial](http://jonathansoma.com/tutorials/d3/using-attr-and-style/) mentioned, here, using \`.attr()\` and \`.style()\` both are fine. The key difference is that I need to use \`return d / 2 + "px"\` for \`stroke-wideth\` when using \`.style()\`.
`
md` ### Concluding words on .style() and .attr():
- For \`<div>\`, \`height\` is a CSS property, so I should use \`style\`;
- For \`<svg>\`, \`height\`, \`width\`, \`x\`, \`y\`, \`cx\`, \`cy\`, \`r\` are attributes, so I should use \`attr()\`;
- For \`<svg>\`, \`fill\`, \`stroke\`, and \`stroke-width\` are also attributes. I can use both \`style()\` and \`attr()\` but \`style()\` is better because it is not about **position** and **size**.
- Refere to [this tutorial](http://jonathansoma.com/tutorials/d3/using-attr-and-style/) and [this tutorial](https://www.carlosrendon.me/unfinished_d3_book/d3_attr.html).
`
md` # Scatterplots
`
md`
- if \`var d = [1, 100]\`, then \`d[0] = 1\`
`
md`## Task 6-6
- 6-6-1. First, create a SVG element before the enclosing tag of \`<body>\`. Set the width of the svg to be 500, and the height 100. Dataset = [ [5, 20], [480, 90], [250, 50], [100, 33], [330, 95], [410, 12], [475, 44], [25, 67], [85, 21], [220, 88] ]. In each hard bracket, the first number is the x, and the second the y. Draw a scatterplot of all these data points. Basically, you are expected to draw small circles. \`cx\` and \`cy\` are the above data points. Set the radius to be 5 pixels.
- In the above \`dataset\`, \`dataset[2][0] = 480\`
- 6-6-2. Label each data point in the format of \`d[0], d[1]\`. Place each label right beside each data point (just use d[0] as x, and d[1] as y will do the job). Please note here that \`text\` can both be an SVG element and a D3 method.
**Chaper Six, Drawing the data** is finally over. We'll begin learning **scales**. p.117
`
md`
Go to [Day 11](https://observablehq.com/@hongtaoh/day-eleven-sept-4th-2020).
`
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