36 lines
922 B
JavaScript
36 lines
922 B
JavaScript
|
|
/* Inspired by Lee Byron's test data generator. */
|
|
function stream_layers(n, m, o) {
|
|
if (arguments.length < 3) o = 0;
|
|
function bump(a) {
|
|
var x = 1 / (.1 + Math.random()),
|
|
y = 2 * Math.random() - .5,
|
|
z = 10 / (.1 + Math.random());
|
|
for (var i = 0; i < m; i++) {
|
|
var w = (i / m - y) * z;
|
|
a[i] += x * Math.exp(-w * w);
|
|
}
|
|
}
|
|
return d3.range(n).map(function() {
|
|
var a = [], i;
|
|
for (i = 0; i < m; i++) a[i] = o + o * Math.random();
|
|
for (i = 0; i < 5; i++) bump(a);
|
|
return a.map(stream_index);
|
|
});
|
|
}
|
|
|
|
/* Another layer generator using gamma distributions. */
|
|
function stream_waves(n, m) {
|
|
return d3.range(n).map(function(i) {
|
|
return d3.range(m).map(function(j) {
|
|
var x = 20 * j / m - i / 3;
|
|
return 2 * x * Math.exp(-.5 * x);
|
|
}).map(stream_index);
|
|
});
|
|
}
|
|
|
|
function stream_index(d, i) {
|
|
return {x: i, y: Math.max(0, d)};
|
|
}
|
|
|