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log.js
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log.js
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import {ticks} from "d3-array";
import {format} from "d3-format";
import constant from "./constant";
import nice from "./nice";
import {default as continuous, copy} from "./continuous";
var tickFormat10 = format(".0e"),
tickFormatOther = format(",");
function deinterpolate(a, b) {
return (b = Math.log(b / a))
? function(x) { return Math.log(x / a) / b; }
: constant(b);
}
function reinterpolate(a, b) {
return a < 0
? function(t) { return -Math.pow(-b, t) * Math.pow(-a, 1 - t); }
: function(t) { return Math.pow(b, t) * Math.pow(a, 1 - t); };
}
function pow10(x) {
return isFinite(x) ? +("1e" + x) : x < 0 ? 0 : x;
}
function powp(base) {
return base === 10 ? pow10
: base === Math.E ? Math.exp
: function(x) { return Math.pow(base, x); };
}
function logp(base) {
return base === Math.E ? Math.log
: base === 10 && Math.log10
|| base === 2 && Math.log2
|| (base = Math.log(base), function(x) { return Math.log(x) / base; });
}
function reflect(f) {
return function(x) {
return -f(-x);
};
}
export default function log() {
var scale = continuous(deinterpolate, reinterpolate).domain([1, 10]),
domain = scale.domain,
base = 10,
logs = logp(10),
pows = powp(10);
function rescale() {
logs = logp(base), pows = powp(base);
if (domain()[0] < 0) logs = reflect(logs), pows = reflect(pows);
return scale;
}
scale.base = function(_) {
return arguments.length ? (base = +_, rescale()) : base;
};
scale.domain = function(_) {
return arguments.length ? (domain(_), rescale()) : domain();
};
scale.ticks = function(count) {
var d = domain(),
u = d[0],
v = d[d.length - 1],
r;
if (r = v < u) i = u, u = v, v = i;
var i = logs(u),
j = logs(v),
p,
k,
t,
n = count == null ? 10 : +count,
z = [];
if (!(base % 1) && j - i < n) {
i = Math.round(i) - 1, j = Math.round(j) + 1;
var testI = i;
while(pows(testI) * base < u) testI++;
if (v - u < pows(testI)) {
z = ticks(u, v, n);
} else if (u > 0) for (; i < j; ++i) {
for (k = 1, p = pows(i); k < base; ++k) {
t = p * k;
if (t < u) continue;
if (t > v) break;
z.push(t);
}
} else for (; i < j; ++i) {
for (k = base - 1, p = pows(i); k >= 1; --k) {
t = p * k;
if (t < u) continue;
if (t > v) break;
z.push(t);
}
}
if (r) z.reverse();
} else {
z = ticks(i, j, Math.min(j - i, n)).map(pows);
}
return z;
};
scale.tickFormat = function(count, specifier) {
if (specifier == null) specifier = base === 10 ? tickFormat10 : tickFormatOther;
else if (typeof specifier !== "function") specifier = format(specifier);
if (count == null) return specifier;
var k = Math.max(1, base * count / scale.ticks().length); // TODO fast estimate?
return function(d) {
var i = d / pows(Math.round(logs(d)));
if (i * base < base - 0.5) i *= base;
return i <= k ? specifier(d) : "";
};
};
scale.nice = function() {
return domain(nice(domain(), {
floor: function(x) { return pows(Math.floor(logs(x))); },
ceil: function(x) { return pows(Math.ceil(logs(x))); }
}));
};
scale.copy = function() {
return copy(scale, log().base(base));
};
return scale;
};