d3-array#ticks JavaScript Examples

export function linearish(scale) {
  var domain = scale.domain;

  scale.ticks = function(count) {
    var d = domain();
    return ticks(d[0], d[d.length - 1], count == null ? 10 : count);
  };

  scale.tickFormat = function(count, specifier) {
    var d = domain();
    return tickFormat(d[0], d[d.length - 1], count == null ? 10 : count, specifier);
  };

  scale.nice = function(count) {
    if (count == null) count = 10;

    var d = domain();
    var i0 = 0;
    var i1 = d.length - 1;
    var start = d[i0];
    var stop = d[i1];
    var prestep;
    var step;
    var maxIter = 10;

    if (stop < start) {
      step = start, start = stop, stop = step;
      step = i0, i0 = i1, i1 = step;
    }
    
    while (maxIter-- > 0) {
      step = tickIncrement(start, stop, count);
      if (step === prestep) {
        d[i0] = start
        d[i1] = stop
        return domain(d);
      } else if (step > 0) {
        start = Math.floor(start / step) * step;
        stop = Math.ceil(stop / step) * step;
      } else if (step < 0) {
        start = Math.ceil(start * step) / step;
        stop = Math.floor(stop * step) / step;
      } else {
        break;
      }
      prestep = step;
    }

    return scale;
  };

  return scale;
}

export function linearish(scale) {
  var domain = scale.domain;

  scale.ticks = function(count) {
    var d = domain();
    return ticks(d[0], d[d.length - 1], count == null ? 10 : count);
  };

  scale.tickFormat = function(count, specifier) {
    var d = domain();
    return tickFormat(d[0], d[d.length - 1], count == null ? 10 : count, specifier);
  };

  scale.nice = function(count) {
    if (count == null) count = 10;

    var d = domain(),
        i0 = 0,
        i1 = d.length - 1,
        start = d[i0],
        stop = d[i1],
        step;

    if (stop < start) {
      step = start, start = stop, stop = step;
      step = i0, i0 = i1, i1 = step;
    }

    step = tickIncrement(start, stop, count);

    if (step > 0) {
      start = Math.floor(start / step) * step;
      stop = Math.ceil(stop / step) * step;
      step = tickIncrement(start, stop, count);
    } else if (step < 0) {
      start = Math.ceil(start * step) / step;
      stop = Math.floor(stop * step) / step;
      step = tickIncrement(start, stop, count);
    }

    if (step > 0) {
      d[i0] = Math.floor(start / step) * step;
      d[i1] = Math.ceil(stop / step) * step;
      domain(d);
    } else if (step < 0) {
      d[i0] = Math.ceil(start * step) / step;
      d[i1] = Math.floor(stop * step) / step;
      domain(d);
    }

    return scale;
  };

  return scale;
}

export function linearish(scale) {
  var domain = scale.domain;

  scale.ticks = function(count) {
    var d = domain();
    return ticks(d[0], d[d.length - 1], count == null ? 10 : count);
  };

  scale.tickFormat = function(count, specifier) {
    return tickFormat(domain(), count, specifier);
  };

  scale.nice = function(count) {
    if (count == null) count = 10;

    var d = domain(),
        i0 = 0,
        i1 = d.length - 1,
        start = d[i0],
        stop = d[i1],
        step;

    if (stop < start) {
      step = start, start = stop, stop = step;
      step = i0, i0 = i1, i1 = step;
    }

    step = tickIncrement(start, stop, count);

    if (step > 0) {
      start = Math.floor(start / step) * step;
      stop = Math.ceil(stop / step) * step;
      step = tickIncrement(start, stop, count);
    } else if (step < 0) {
      start = Math.ceil(start * step) / step;
      stop = Math.floor(stop * step) / step;
      step = tickIncrement(start, stop, count);
    }

    if (step > 0) {
      d[i0] = Math.floor(start / step) * step;
      d[i1] = Math.ceil(stop / step) * step;
      domain(d);
    } else if (step < 0) {
      d[i0] = Math.ceil(start * step) / step;
      d[i1] = Math.floor(stop * step) / step;
      domain(d);
    }

    return scale;
  };

  return scale;
}

export default function() {
  var dx = 1,
      dy = 1,
      threshold = thresholdSturges,
      smooth = smoothLinear;

  function contours(values) {
    var tz = threshold(values);

    // Convert number of thresholds into uniform thresholds.
    if (!Array.isArray(tz)) {
      const e = extent(values), ts = tickStep(e[0], e[1], tz);
      tz = ticks(Math.floor(e[0] / ts) * ts, Math.floor(e[1] / ts - 1) * ts, tz);
    } else {
      tz = tz.slice().sort(ascending);
    }

    return tz.map(value => contour(values, value));
  }

  // Accumulate, smooth contour rings, assign holes to exterior rings.
  // Based on https://github.com/mbostock/shapefile/blob/v0.6.2/shp/polygon.js
  function contour(values, value) {
    var polygons = [],
        holes = [];

    isorings(values, value, function(ring) {
      smooth(ring, values, value);
      if (area(ring) > 0) polygons.push([ring]);
      else holes.push(ring);
    });

    holes.forEach(function(hole) {
      for (var i = 0, n = polygons.length, polygon; i < n; ++i) {
        if (contains((polygon = polygons[i])[0], hole) !== -1) {
          polygon.push(hole);
          return;
        }
      }
    });

    return {
      type: "MultiPolygon",
      value: value,
      coordinates: polygons
    };
  }

  // Marching squares with isolines stitched into rings.
  // Based on https://github.com/topojson/topojson-client/blob/v3.0.0/src/stitch.js
  function isorings(values, value, callback) {
    var fragmentByStart = new Array,
        fragmentByEnd = new Array,
        x, y, t0, t1, t2, t3;

    // Special case for the first row (y = -1, t2 = t3 = 0).
    x = y = -1;
    t1 = values[0] >= value;
    cases[t1 << 1].forEach(stitch);
    while (++x < dx - 1) {
      t0 = t1, t1 = values[x + 1] >= value;
      cases[t0 | t1 << 1].forEach(stitch);
    }
    cases[t1 << 0].forEach(stitch);

    // General case for the intermediate rows.
    while (++y < dy - 1) {
      x = -1;
      t1 = values[y * dx + dx] >= value;
      t2 = values[y * dx] >= value;
      cases[t1 << 1 | t2 << 2].forEach(stitch);
      while (++x < dx - 1) {
        t0 = t1, t1 = values[y * dx + dx + x + 1] >= value;
        t3 = t2, t2 = values[y * dx + x + 1] >= value;
        cases[t0 | t1 << 1 | t2 << 2 | t3 << 3].forEach(stitch);
      }
      cases[t1 | t2 << 3].forEach(stitch);
    }

    // Special case for the last row (y = dy - 1, t0 = t1 = 0).
    x = -1;
    t2 = values[y * dx] >= value;
    cases[t2 << 2].forEach(stitch);
    while (++x < dx - 1) {
      t3 = t2, t2 = values[y * dx + x + 1] >= value;
      cases[t2 << 2 | t3 << 3].forEach(stitch);
    }
    cases[t2 << 3].forEach(stitch);

    function stitch(line) {
      var start = [line[0][0] + x, line[0][1] + y],
          end = [line[1][0] + x, line[1][1] + y],
          startIndex = index(start),
          endIndex = index(end),
          f, g;
      if (f = fragmentByEnd[startIndex]) {
        if (g = fragmentByStart[endIndex]) {
          delete fragmentByEnd[f.end];
          delete fragmentByStart[g.start];
          if (f === g) {
            f.ring.push(end);
            callback(f.ring);
          } else {
            fragmentByStart[f.start] = fragmentByEnd[g.end] = {start: f.start, end: g.end, ring: f.ring.concat(g.ring)};
          }
        } else {
          delete fragmentByEnd[f.end];
          f.ring.push(end);
          fragmentByEnd[f.end = endIndex] = f;
        }
      } else if (f = fragmentByStart[endIndex]) {
        if (g = fragmentByEnd[startIndex]) {
          delete fragmentByStart[f.start];
          delete fragmentByEnd[g.end];
          if (f === g) {
            f.ring.push(end);
            callback(f.ring);
          } else {
            fragmentByStart[g.start] = fragmentByEnd[f.end] = {start: g.start, end: f.end, ring: g.ring.concat(f.ring)};
          }
        } else {
          delete fragmentByStart[f.start];
          f.ring.unshift(start);
          fragmentByStart[f.start = startIndex] = f;
        }
      } else {
        fragmentByStart[startIndex] = fragmentByEnd[endIndex] = {start: startIndex, end: endIndex, ring: [start, end]};
      }
    }
  }

  function index(point) {
    return point[0] * 2 + point[1] * (dx + 1) * 4;
  }

  function smoothLinear(ring, values, value) {
    ring.forEach(function(point) {
      var x = point[0],
          y = point[1],
          xt = x | 0,
          yt = y | 0,
          v0,
          v1 = values[yt * dx + xt];
      if (x > 0 && x < dx && xt === x) {
        v0 = values[yt * dx + xt - 1];
        point[0] = x + (value - v0) / (v1 - v0) - 0.5;
      }
      if (y > 0 && y < dy && yt === y) {
        v0 = values[(yt - 1) * dx + xt];
        point[1] = y + (value - v0) / (v1 - v0) - 0.5;
      }
    });
  }

  contours.contour = contour;

  contours.size = function(_) {
    if (!arguments.length) return [dx, dy];
    var _0 = Math.floor(_[0]), _1 = Math.floor(_[1]);
    if (!(_0 >= 0 && _1 >= 0)) throw new Error("invalid size");
    return dx = _0, dy = _1, contours;
  };

  contours.thresholds = function(_) {
    return arguments.length ? (threshold = typeof _ === "function" ? _ : Array.isArray(_) ? constant(slice.call(_)) : constant(_), contours) : threshold;
  };

  contours.smooth = function(_) {
    return arguments.length ? (smooth = _ ? smoothLinear : noop, contours) : smooth === smoothLinear;
  };

  return contours;
}

export function loggish(transform) {
  const scale = transform(transformLog, transformExp);
  const domain = scale.domain;
  let base = 10;
  let logs;
  let pows;

  function rescale() {
    logs = logp(base), pows = powp(base);
    if (domain()[0] < 0) {
      logs = reflect(logs), pows = reflect(pows);
      transform(transformLogn, transformExpn);
    } else {
      transform(transformLog, transformExp);
    }
    return scale;
  }

  scale.base = function(_) {
    return arguments.length ? (base = +_, rescale()) : base;
  };

  scale.domain = function(_) {
    return arguments.length ? (domain(_), rescale()) : domain();
  };

  scale.ticks = count => {
    const d = domain();
    let u = d[0];
    let v = d[d.length - 1];
    const r = v < u;

    if (r) ([u, v] = [v, u]);

    let i = logs(u);
    let j = logs(v);
    let k;
    let t;
    const n = count == null ? 10 : +count;
    let z = [];

    if (!(base % 1) && j - i < n) {
      i = Math.floor(i), j = Math.ceil(j);
      if (u > 0) for (; i <= j; ++i) {
        for (k = 1; k < base; ++k) {
          t = i < 0 ? k / pows(-i) : k * pows(i);
          if (t < u) continue;
          if (t > v) break;
          z.push(t);
        }
      } else for (; i <= j; ++i) {
        for (k = base - 1; k >= 1; --k) {
          t = i > 0 ? k / pows(-i) : k * pows(i);
          if (t < u) continue;
          if (t > v) break;
          z.push(t);
        }
      }
      if (z.length * 2 < n) z = ticks(u, v, n);
    } else {
      z = ticks(i, j, Math.min(j - i, n)).map(pows);
    }
    return r ? z.reverse() : z;
  };

  scale.tickFormat = (count, specifier) => {
    if (count == null) count = 10;
    if (specifier == null) specifier = base === 10 ? "s" : ",";
    if (typeof specifier !== "function") {
      if (!(base % 1) && (specifier = formatSpecifier(specifier)).precision == null) specifier.trim = true;
      specifier = format(specifier);
    }
    if (count === Infinity) return specifier;
    const k = Math.max(1, base * count / scale.ticks().length); // TODO fast estimate?
    return d => {
      let i = d / pows(Math.round(logs(d)));
      if (i * base < base - 0.5) i *= base;
      return i <= k ? specifier(d) : "";
    };
  };

  scale.nice = () => {
    return domain(nice(domain(), {
      floor: x => pows(Math.floor(logs(x))),
      ceil: x => pows(Math.ceil(logs(x)))
    }));
  };

  return scale;
}

export function loggish(transform) {
  var scale = transform(transformLog, transformExp),
      domain = scale.domain,
      base = 10,
      logs,
      pows;

  function rescale() {
    logs = logp(base), pows = powp(base);
    if (domain()[0] < 0) {
      logs = reflect(logs), pows = reflect(pows);
      transform(transformLogn, transformExpn);
    } else {
      transform(transformLog, transformExp);
    }
    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;
      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);
        }
      }
    } else {
      z = ticks(i, j, Math.min(j - i, n)).map(pows);
    }

    return r ? z.reverse() : z;
  };

  scale.tickFormat = function(count, specifier) {
    if (specifier == null) specifier = base === 10 ? ".0e" : ",";
    if (typeof specifier !== "function") specifier = format(specifier);
    if (count === Infinity) return specifier;
    if (count == null) count = 10;
    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))); }
    }));
  };

  return scale;
}

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;
      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);
        }
      }
    } else {
      z = ticks(i, j, Math.min(j - i, n)).map(pows);
    }

    return r ? z.reverse() : z;
  };

  scale.tickFormat = function(count, specifier) {
    if (specifier == null) specifier = base === 10 ? ".0e" : ",";
    if (typeof specifier !== "function") specifier = format(specifier);
    if (count === Infinity) return specifier;
    if (count == null) count = 10;
    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;
}