Roll Observatory packages and add a roll script

charted/lib/core/scales/log_scale.dart

-//
-// Copyright 2014 Google Inc. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-//
-part of charted.core.scales;
-
-/// Log scale is similar to linear scale, except there's a logarithmic
-/// transform that is applied to the input domain value before the output
-/// range value is computed.
-///
-/// The mapping to the output range value y can be expressed as a function
-/// of the input domain value x: y = m log(x) + b.
-///
-/// As log(0) is negative infinity, a log scale must have either an
-/// exclusively-positive or exclusively-negative domain; the domain must not
-/// include or cross zero.
-class LogScale implements Scale {
-  static const defaultBase = 10;
-  static const defaultDomain = const [1, 10];
-  static final negativeNumbersRoundFunctionsPair =
-      new RoundingFunctions(
-          (x) => -((-x).floor()),
-          (x) => -((-x).ceil()));
-
-  final LinearScale _linear;
-
-  bool _nice = false;
-  int _base = defaultBase;
-  int _ticksCount = 10;
-  bool _positive = true;
-  List _domain = defaultDomain;
-
-  LogScale() : _linear = new LinearScale();
-
-  LogScale._clone(LogScale source)
-      : _linear = source._linear.clone(),
-        _domain = source._domain.toList(),
-        _positive = source._positive,
-        _base = source._base,
-        _nice = source._nice,
-        _ticksCount = source._ticksCount;
-
-  num _log(x) => (_positive ?
-      math.log(x < 0 ? 0 : x) : -math.log(x > 0 ? 0 : -x)) / math.log(base);
-
-  num _pow(x) => _positive ? math.pow(base, x) : -math.pow(base, -x);
-
-  set base(int value) {
-    if (_base != value) {
-      _base = value;
-      _reset();
-    }
-  }
-
-  get base => _base;
-
-  @override
-  num scale(x) => _linear.scale(_log(x));
-
-  @override
-  num invert(x) => _pow(_linear.invert(x));
-
-  @override
-  set domain(Iterable values) {
-    _positive = values.first >= 0;
-    _domain = values;
-    _reset();
-  }
-
-  @override
-  Iterable get domain => _domain;
-
-  @override
-  set range(Iterable newRange) {
-    _linear.range = newRange;
-  }
-
-  @override
-  Iterable get range => _linear.range;
-
-  @override
-  set rounded(bool value) {
-    _linear.rounded = value;
-  }
-
-  @override
-  bool get rounded => _linear.rounded;
-
-  @override
-  set nice(bool value) {
-    if (_nice != value) {
-      _nice = value;
-      _reset();
-    }
-  }
-
-  @override
-  bool get nice => _nice;
-
-  @override
-  set ticksCount(int value) {
-    if (_ticksCount != value) {
-      _ticksCount = value;
-      _reset();
-    }
-  }
-
-  @override
-  int get ticksCount => _ticksCount;
-
-  @override
-  set clamp(bool value) {
-    _linear.clamp = value;
-  }
-
-  @override
-  bool get clamp => _linear.clamp;
-
-  @override
-  Extent get rangeExtent => _linear.rangeExtent;
-
-  _reset() {
-    if (_nice) {
-      var niced = _domain.map((e) => _log(e)).toList();
-      var roundFunctions = _positive
-          ? new RoundingFunctions.defaults()
-          : negativeNumbersRoundFunctionsPair;
-
-      _linear.domain = ScaleUtils.nice(niced, roundFunctions);
-      _domain = niced.map((e) => _pow(e)).toList();
-    } else {
-      _linear.domain = _domain.map((e) => _log(e)).toList();
-    }
-  }
-
-  Iterable get ticks {
-    var extent = ScaleUtils.extent(_domain),
-        ticks = [],
-        u = extent.min,
-        v = extent.max,
-        i = (_log(u)).floor(),
-        j = (_log(v)).ceil(),
-        n = (_base % 1 > 0) ? 2 : _base;
-
-    if ((j - i).isFinite) {
-      if (_positive) {
-        for (; i < j; i++) for (var k = 1; k < n; k++) ticks.add(_pow(i) * k);
-        ticks.add(_pow(i));
-      } else {
-        ticks.add(_pow(i));
-        for (; i++ < j;) for (var k = n - 1; k > 0; k--) ticks.add(_pow(i) * k);
-      }
-      for (i = 0; ticks[i] < u; i++) {} // strip small values
-      for (j = ticks.length; ticks[j - 1] > v; j--) {} // strip big values
-      ticks = ticks.sublist(i, j);
-    }
-    return ticks;
-  }
-
-  FormatFunction createTickFormatter([String formatStr]) {
-    NumberFormat formatter = new NumberFormat(new EnUsLocale());
-    FormatFunction logFormatFunction =
-        formatter.format(formatStr != null ? formatStr : ".0E");
-    var k = math.max(.1, ticksCount / this.ticks.length),
-        e = _positive ? 1e-12 : -1e-12;
-    return (d) {
-      if (_positive) {
-        return d / _pow((_log(d) + e).ceil()) <= k ? logFormatFunction(d) : '';
-      } else {
-        return d / _pow((_log(d) + e).floor()) <= k ? logFormatFunction(d) : '';
-      }
-    };
-  }
-
-  @override
-  LogScale clone() => new LogScale._clone(this);
-}