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 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 Ten (Task 6-6), Sept. 3rd, 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 31 (9-2-10), 2020-09-24
md`# Day 31 (9-2-10), 2020-09-24`
md`
9-2-10. Create a \`p\` element with the text "Click here to remove data". Every time you click it, the first bar and its associated label will be removed. Add a transition (half a second) to the removal so that the **exiting** bar will move to the bottom-right corner of the SVG and then disappear. Make sure to update the bars and labels.
`
md`
*Hint* :
- To remove the first data value from dataset, use \`.shift()\`;
- To remove svg elements (rect and text), use \`.exit().remove()\`. The \`.exit()\` function returns a reference to the exiting element; Transition syntaxes should be added between \`.exit()\` and \`.remove()\`.
- To make sure that the exiting bar moves to the bottom-right corner before disappearing, set its position after the transition and before the removal;
- After the removal, we need to update the bars and labels. That's fairly easy. For \`rect\`, just use \`svg.selectAll("rect")\`, and then set its position, width, height and color using \`attr("x", ...)...\`. For \`text\`, first use \`svg.selectAll("text").text(d => d)\`, and then set texts' positions.
`
md`
Something I don't understand but don't have time to figure out:
- I want to let the eixiting label to turn red and move to the upper-right corner before disappearing, so I specified \`.attr("x", w).attr("y", 0).\` after the transition syntaxes and before \`.remove()\`. However, I noticed that it just cannot move horizontally. It keeps within its original horizontal position.
- I just don't know why and how [Scott Murray's codes](https://github.com/scotthmurray/d3-book/blob/master/chapter_09/26_removing_values.html) worked. Why should we use \`bars.enter()...\` here?
- How to get the transition in [Scott Murray's codes](https://github.com/scotthmurray/d3-book/blob/master/chapter_09/26_removing_values.html) when updating the bars?
- I used \`dataset.pop()\`, which is supposed to delete the last data value. Yes, when I used
\`svg.selectAll("rect")
.data(dataset)
.exit()
.transition()
.attr("x", w)
.attr("y", h)
.remove()
\`
The exiting bar traveled from the left! Why???
`
md`
## Clearly, there are just so many points that I didn't get in terms of removing data values. Unfortunately, I don't have to time to understand them now. I have to move on.
`
md`
Go to [Day 32](https://observablehq.com/@hongtaoh/day-32-2020-09-25).
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