Hexbin Density
Code
ChartUtil.tsx
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"use client";
// reference: https://d3-graph-gallery.com/graph/density2d_hexbin.html
import { ChartProps } from "@/types";
import React, { useRef, useCallback, useEffect } from "react";
import { useResizeObserver } from "@/hooks/useResizeObserver";
import * as d3 from "d3";
// @ts-ignore
import * as d3Hexbin from "d3-hexbin";
const ChartUtil = ({ data: rawData }: ChartProps) => {
const containerRef = useRef<HTMLDivElement | null>(null);
const data = Object.values(rawData);
const renderFunc = useCallback(() => {
const container = containerRef.current as HTMLElement;
if (!container) return;
const margin = { top: 50, right: 25, bottom: 25, left: 25 },
width = container.offsetWidth - margin.left - margin.right,
height = 640 - margin.top - margin.bottom;
// append the svg object to the body of the page
const svg = d3
.select(container)
.html("")
.append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", `translate(${margin.left}, ${margin.top})`);
// Add X axis
const x = d3.scaleLinear().domain([5, 18]).range([0, width]);
svg
.append("g")
.attr("transform", `translate(0, ${height})`)
.call(d3.axisBottom(x))
.call((d) =>
d
.selectAll("text")
.attr("font-family", "Space Mono")
.attr("font-size", 14)
);
// Add Y axis
const y = d3.scaleLinear().domain([5, 20]).range([height, 0]);
svg
.append("g")
.call(d3.axisLeft(y))
.call((d) =>
d
.selectAll("text")
.attr("font-family", "Space Mono")
.attr("font-size", 14)
);
// Reformat the data: d3-hexbin() needs a specific format
const inputForHexbinFun: any[] = [];
data.forEach(function (d: any) {
inputForHexbinFun.push([x(d.x), y(d.y)]); // Note that we had the transform value of X and Y !
});
// Prepare a color palette
const color = d3
.scaleLinear<string, number>()
.domain([0, 250]) // Number of points in the bin?
.range(["transparent", "#038aff"]);
// Compute the hexbin data
const hexbin = d3Hexbin
.hexbin()
.radius(9) // size of the bin in px
.extent([
[0, 0],
[width, height],
]);
// Plot the hexbins
svg
.append("clipPath")
.attr("id", "clip")
.append("rect")
.attr("width", width)
.attr("height", height);
svg
.append("g")
.attr("clip-path", "url(#clip)")
.selectAll("path")
.data(hexbin(inputForHexbinFun))
.join("path")
.attr("d", hexbin.hexagon())
.attr("transform", function (d: any) {
return `translate(${d.x}, ${d.y})`;
})
.attr("fill", function (d: any) {
return color(d.length);
})
.attr("stroke", "#fff")
.attr("stroke-width", "0.1");
}, [data]);
useEffect(() => {
containerRef.current !== null && renderFunc();
}, [renderFunc]);
const resizeHandler = useCallback(() => {
containerRef.current !== null && renderFunc();
}, [renderFunc]);
useResizeObserver(containerRef, resizeHandler);
return <div ref={containerRef}></div>;
};
export default ChartUtil;