A bubble chart extending scatter plots by adding a third dimension through bubble size. Each point's position shows two variables (x, y) while the bubble size represents a third quantitative variable. This visualization is excellent for understanding relationships between three numerical variables simultaneously, revealing patterns that would be hidden in traditional 2D scatter plots.
// anyplot.ai
// bubble-basic: Basic Bubble Chart
// Library: d3 7.9.0 | JavaScript 22.23.2
// Quality: 91/100 | Created: 2026-08-24
const t = window.ANYPLOT_TOKENS;
const { width, height } = window.ANYPLOT_SIZE;
const margin = { top: 100, right: 60, bottom: 90, left: 100 };
const iw = width - margin.left - margin.right;
const ih = height - margin.top - margin.bottom;
// --- Data (in-memory, deterministic) ----------------------------------------
// Startup funding rounds: funding raised vs. revenue growth rate, bubble size
// encodes team size — funding drives hiring, while growth slows as rounds grow.
function lcg(seed) {
let state = seed;
return () => {
state = (state * 1664525 + 1013904223) >>> 0;
return state / 4294967296;
};
}
const rand = lcg(42);
const n = 120;
const data = [];
for (let i = 0; i < n; i++) {
const funding = 2 + rand() * 148;
const growth = 55 - funding * 0.25 + (rand() - 0.5) * 45;
const team = 10 + funding * 0.55 + (rand() - 0.5) * 20;
data.push({
funding: Math.round(funding * 10) / 10,
growth: Math.round(growth * 10) / 10,
team: Math.round(Math.min(100, Math.max(10, team))),
});
}
// --- SVG mount ----------------------------------------------------------------
const svg = d3.select("#container").append("svg").attr("width", width).attr("height", height);
const g = svg.append("g").attr("transform", `translate(${margin.left},${margin.top})`);
// --- Scales ---------------------------------------------------------------
const x = d3.scaleLinear().domain([0, d3.max(data, (d) => d.funding)]).nice().range([0, iw]);
const y = d3.scaleLinear().domain(d3.extent(data, (d) => d.growth)).nice().range([ih, 0]);
const teamExtent = d3.extent(data, (d) => d.team);
const r = d3.scaleSqrt().domain(teamExtent).range([8, 34]);
// --- Gridlines --------------------------------------------------------------
const gridX = g.append("g")
.attr("transform", `translate(0,${ih})`)
.call(d3.axisBottom(x).tickSize(-ih).tickFormat(""));
const gridY = g.append("g").call(d3.axisLeft(y).tickSize(-iw).tickFormat(""));
for (const grid of [gridX, gridY]) {
grid.select(".domain").remove();
grid.selectAll("line").attr("stroke", t.grid).attr("stroke-opacity", 0.5);
}
// --- Axes ---------------------------------------------------------------------
const xAxis = g.append("g").attr("transform", `translate(0,${ih})`).call(d3.axisBottom(x));
const yAxis = g.append("g").call(d3.axisLeft(y));
for (const ax of [xAxis, yAxis]) {
ax.selectAll("text").attr("fill", t.inkSoft).style("font-size", "14px");
ax.selectAll("line").attr("stroke", t.inkSoft);
ax.select(".domain").attr("stroke", t.inkSoft);
}
// --- Axis labels --------------------------------------------------------------
g.append("text")
.attr("x", iw / 2)
.attr("y", ih + 60)
.attr("text-anchor", "middle")
.attr("fill", t.ink)
.style("font-size", "16px")
.text("Funding Raised ($M)");
g.append("text")
.attr("transform", "rotate(-90)")
.attr("x", -ih / 2)
.attr("y", -70)
.attr("text-anchor", "middle")
.attr("fill", t.ink)
.style("font-size", "16px")
.text("Revenue Growth Rate (%)");
// --- Bubbles --------------------------------------------------------------
g.selectAll("circle.bubble").data(data).join("circle")
.attr("class", "bubble")
.attr("cx", (d) => x(d.funding))
.attr("cy", (d) => y(d.growth))
.attr("r", (d) => r(d.team))
.attr("fill", t.palette[0])
.attr("fill-opacity", 0.48)
.attr("stroke", t.pageBg)
.attr("stroke-width", 1);
// --- Trend annotation -------------------------------------------------------
// Least-squares fit of growth vs. funding, drawn as a dashed guide so the
// negative correlation is called out explicitly rather than left implicit.
const sumX = d3.sum(data, (d) => d.funding);
const sumY = d3.sum(data, (d) => d.growth);
const sumXY = d3.sum(data, (d) => d.funding * d.growth);
const sumXX = d3.sum(data, (d) => d.funding * d.funding);
const slope = (n * sumXY - sumX * sumY) / (n * sumXX - sumX * sumX);
const intercept = (sumY - slope * sumX) / n;
const [fundingMin, fundingMax] = d3.extent(data, (d) => d.funding);
g.append("line")
.attr("x1", x(fundingMin))
.attr("y1", y(slope * fundingMin + intercept))
.attr("x2", x(fundingMax))
.attr("y2", y(slope * fundingMax + intercept))
.attr("stroke", t.inkSoft)
.attr("stroke-width", 2)
.attr("stroke-dasharray", "8,6")
.attr("stroke-opacity", 0.6);
const trendLabelX = x(fundingMin) + (x(fundingMax) - x(fundingMin)) * 0.62;
const trendLabelY = y(slope * (fundingMin + (fundingMax - fundingMin) * 0.62) + intercept) - 16;
g.append("text")
.attr("x", trendLabelX)
.attr("y", trendLabelY)
.attr("text-anchor", "middle")
.attr("fill", t.inkSoft)
.style("font-size", "14px")
.style("font-style", "italic")
.text("Growth slows as funding scales up");
// --- Size legend ------------------------------------------------------------
const teamMedian = d3.median(data, (d) => d.team);
const legendValues = [
Math.round(teamExtent[0] / 5) * 5,
Math.round(teamMedian / 5) * 5,
Math.round(teamExtent[1] / 5) * 5,
];
const legendR = legendValues.map((v) => r(v));
const legendBoxW = 260;
const legendBoxH = 140;
const legend = svg.append("g")
.attr("transform", `translate(${margin.left + iw - legendBoxW + 10},${margin.top - 20})`);
legend.append("rect")
.attr("width", legendBoxW)
.attr("height", legendBoxH)
.attr("fill", t.elevatedBg)
.attr("stroke", t.grid)
.attr("rx", 8);
legend.append("text")
.attr("x", legendBoxW / 2)
.attr("y", 28)
.attr("text-anchor", "middle")
.attr("fill", t.inkSoft)
.style("font-size", "14px")
.text("Team Size (employees)");
const baselineY = 110;
const legendX = [60, 140, 210];
legendValues.forEach((v, i) => {
legend.append("circle")
.attr("cx", legendX[i])
.attr("cy", baselineY - legendR[i])
.attr("r", legendR[i])
.attr("fill", "none")
.attr("stroke", t.inkSoft)
.attr("stroke-width", 1.5);
legend.append("text")
.attr("x", legendX[i])
.attr("y", baselineY + 22)
.attr("text-anchor", "middle")
.attr("fill", t.inkSoft)
.style("font-size", "13px")
.text(v);
});
// --- Title ------------------------------------------------------------------
svg.append("text")
.attr("x", width / 2)
.attr("y", 44)
.attr("text-anchor", "middle")
.attr("fill", t.ink)
.style("font-size", "22px")
.style("font-weight", "600")
.text("bubble-basic · javascript · d3 · anyplot.ai");
Part of Basic Bubble Chart on anyplot.ai.