Ramon Weber,
PhD Student @ MIT
Sustainable Design Lab & Digital Structures Group
favorability = FileAttachment("us-president-favorability.csv").csv({typed: true})
addTooltips(
Plot.dot(favorability, {
x: "First Inauguration Date",
y: d => metric.value(d) / 100,
title: (d) =>
`${d.Name}\n First Inauguration Date: ${d["First Inauguration Date"].getUTCFullYear()} \n Favorability: ${metric.value(d) / 100}` // \n makes a new line
}).plot(),
)
temp_of = FileAttachment("temp_of.jpg").image()
addTooltips = (chart, styles) => {
const stroke_styles = { stroke: "blue", "stroke-width": 3 };
const fill_styles = { fill: "blue", opacity: 0.5 };
// Workaround if it's in a figure
const type = d3.select(chart).node().tagName;
let wrapper =
type === "FIGURE" ? d3.select(chart).select("svg") : d3.select(chart);
// Workaround if there's a legend....
const svgs = d3.select(chart).selectAll("svg");
if (svgs.size() > 1) wrapper = d3.select([...svgs].pop());
wrapper.style("overflow", "visible"); // to avoid clipping at the edges
// Set pointer events to visibleStroke if the fill is none (e.g., if its a line)
wrapper.selectAll("path").each(function (data, index, nodes) {
// For line charts, set the pointer events to be visible stroke
if (
d3.select(this).attr("fill") === null ||
d3.select(this).attr("fill") === "none"
) {
d3.select(this).style("pointer-events", "visibleStroke");
if (styles === undefined) styles = stroke_styles;
}
});
if (styles === undefined) styles = fill_styles;
const tip = wrapper
.selectAll(".hover")
.data([1])
.join("g")
.attr("class", "hover")
.style("pointer-events", "none")
.style("text-anchor", "middle");
// Add a unique id to the chart for styling
const id = id_generator();
// Add the event listeners
d3.select(chart).classed(id, true); // using a class selector so that it doesn't overwrite the ID
wrapper.selectAll("title").each(function () {
// Get the text out of the title, set it as an attribute on the parent, and remove it
const title = d3.select(this); // title element that we want to remove
const parent = d3.select(this.parentNode); // visual mark on the screen
const t = title.text();
if (t) {
parent.attr("__title", t).classed("has-title", true);
title.remove();
}
// Mouse events
parent
.on("pointerenter pointermove", function (event) {
const text = d3.select(this).attr("__title");
const pointer = d3.pointer(event, wrapper.node());
if (text) tip.call(hover, pointer, text.split("\n"));
else tip.selectAll("*").remove();
// Raise it
d3.select(this).raise();
// Keep within the parent horizontally
const tipSize = tip.node().getBBox();
if (pointer[0] + tipSize.x < 0)
tip.attr(
"transform",
`translate(${tipSize.width / 2}, ${pointer[1] + 7})`
);
else if (pointer[0] + tipSize.width / 2 > wrapper.attr("width"))
tip.attr(
"transform",
`translate(${wrapper.attr("width") - tipSize.width / 2}, ${
pointer[1] + 7
})`
);
})
.on("pointerout", function (event) {
tip.selectAll("*").remove();
// Lower it!
d3.select(this).lower();
});
});
// Remove the tip if you tap on the wrapper (for mobile)
wrapper.on("touchstart", () => tip.selectAll("*").remove());
// Define the styles
chart.appendChild(html`<style>
.${id} .has-title { cursor: pointer; pointer-events: all; }
.${id} .has-title:hover { ${Object.entries(styles).map(([key, value]) => `${key}: ${value};`).join(" ")} }`);
return chart;
}
// Function to position the tooltip
hover = (tip, pos, text) => {
const side_padding = 10;
const vertical_padding = 5;
const vertical_offset = 15;
// Empty it out
tip.selectAll("*").remove();
// Append the text
tip
.style("text-anchor", "middle")
.style("pointer-events", "none")
.attr("transform", `translate(${pos[0]}, ${pos[1] + 7})`)
.selectAll("text")
.data(text)
.join("text")
.style("dominant-baseline", "ideographic")
.text((d) => d)
.attr("y", (d, i) => (i - (text.length - 1)) * 15 - vertical_offset)
.style("font-weight", (d, i) => (i === 0 ? "bold" : "normal"));
const bbox = tip.node().getBBox();
// Add a rectangle (as background)
tip
.append("rect")
.attr("y", bbox.y - vertical_padding)
.attr("x", bbox.x - side_padding)
.attr("width", bbox.width + side_padding * 2)
.attr("height", bbox.height + vertical_padding * 2)
.style("fill", "white")
.style("stroke", "#d3d3d3")
.lower();
}
// To generate a unique ID for each chart so that they styles only apply to that chart
id_generator = () => {
var S4 = function () {
return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
};
return "a" + S4() + S4();
}
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
