Data visualization and analysis at the University of Washington, Seattle.
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Edited
Jan 29, 2024
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data = aq
.table({ hours })
.transform(bindot('hours', { step, smooth }))
qdata = aq
.table({ p: op.sequence(0.5 / numQuantiles, 1, 1 / numQuantiles) })
.derive({ q: d => op.qlnorm(d.p, Math.log(11.4), 0.2) })
.transform(bindot('q', { step: qstep, smooth: false }))
/**
* Dot density binning for dot plot construction.
* Based on Leland Wilkinson, Dot Plots, The American Statistician, 1999.
* https://www.cs.uic.edu/~wilkinson/Publications/dotplots.pdf
* @param {number[]} x The values to bin, in ascending sort order.
* @param {number} step The step size between bins, in units of the data domain.
* @param {boolean} [smooth=false] Flag indicating if smoothing should be performed.
* @return A new array of dot bin locations.
*/
function dotbin(x, step, smooth = false) {
x = x.slice(); // make a protective copy
const n = x.length;
let left = 0; // left index of the current bin
// scan from left, group points less than one step away
for (let j = 1; j < n; ++j) {
if (x[j] >= x[left] + step) {
// use span mid-point, unless that could cause overlap
const xmid = Math.min((x[left] + x[j-1]) / 2, x[j] - step);
x.fill(xmid, left, j);
left = j;
}
}
x.fill((x[left] + x[n-1]) / 2, left, n);
// if requested, smooth to reduce variance and balance "adjacent" bins
// Wilkinson defines adjacent as within step / 4 units
if (smooth) {
const thresh = step + step / 4;
let a = 0, b = 1;
while (x[a] === x[b]) ++b; // get left bin
while (b < n) {
let c = b + 1;
while (x[b] === x[c]) ++c; // get right bin
// are bins adjacent? if so, balance them
if (x[b] - x[a] < thresh) {
const mid = (a + c) >> 1;
x.fill(x[b], mid, b);
x.fill(x[a], b, mid);
}
a = b, b = c; // update left bin indices
}
}
return x;
}
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.
