/**
 * Returns a new categorical color encoding using the specified colors.  The
 * arguments to this method are an array of colors; see {@link pv.color}. For
 * example, to create a categorical color encoding using the <tt>species</tt>
 * attribute:
 *
 * <pre>pv.colors("red", "green", "blue").by(function(d) d.species)</pre>
 *
 * The result of this expression can be used as a fill- or stroke-style
 * property. This assumes that the data's <tt>species</tt> attribute is a
 * string.
 *
 * @param {string} colors... categorical colors.
 * @see pv.Scale.ordinal
 * @returns {pv.Scale.ordinal} an ordinal color scale.
 */
pv.colors = function() {
  var scale = pv.Scale.ordinal();
  scale.range.apply(scale, arguments);
  return scale;
};

/**
 * A collection of standard color palettes for categorical encoding.
 *
 * @namespace A collection of standard color palettes for categorical encoding.
 */
pv.Colors = {};

/**
 * Returns a new 10-color scheme. The arguments to this constructor are
 * optional, and equivalent to calling {@link pv.Scale.OrdinalScale#domain}. The
 * following colors are used:
 *
 * <div style="background:#1f77b4;">#1f77b4</div>
 * <div style="background:#ff7f0e;">#ff7f0e</div>
 * <div style="background:#2ca02c;">#2ca02c</div>
 * <div style="background:#d62728;">#d62728</div>
 * <div style="background:#9467bd;">#9467bd</div>
 * <div style="background:#8c564b;">#8c564b</div>
 * <div style="background:#e377c2;">#e377c2</div>
 * <div style="background:#7f7f7f;">#7f7f7f</div>
 * <div style="background:#bcbd22;">#bcbd22</div>
 * <div style="background:#17becf;">#17becf</div>
 *
 * @param {number...} domain... domain values.
 * @returns {pv.Scale.ordinal} a new ordinal color scale.
 * @see pv.color
 */
pv.Colors.category10 = function() {
  var scale = pv.colors(
      "#1f77b4", "#ff7f0e", "#2ca02c", "#d62728", "#9467bd",
      "#8c564b", "#e377c2", "#7f7f7f", "#bcbd22", "#17becf");
  scale.domain.apply(scale, arguments);
  return scale;
};

/**
 * Returns a new 20-color scheme. The arguments to this constructor are
 * optional, and equivalent to calling {@link pv.Scale.OrdinalScale#domain}. The
 * following colors are used:
 *
 * <div style="background:#1f77b4;">#1f77b4</div>
 * <div style="background:#aec7e8;">#aec7e8</div>
 * <div style="background:#ff7f0e;">#ff7f0e</div>
 * <div style="background:#ffbb78;">#ffbb78</div>
 * <div style="background:#2ca02c;">#2ca02c</div>
 * <div style="background:#98df8a;">#98df8a</div>
 * <div style="background:#d62728;">#d62728</div>
 * <div style="background:#ff9896;">#ff9896</div>
 * <div style="background:#9467bd;">#9467bd</div>
 * <div style="background:#c5b0d5;">#c5b0d5</div>
 * <div style="background:#8c564b;">#8c564b</div>
 * <div style="background:#c49c94;">#c49c94</div>
 * <div style="background:#e377c2;">#e377c2</div>
 * <div style="background:#f7b6d2;">#f7b6d2</div>
 * <div style="background:#7f7f7f;">#7f7f7f</div>
 * <div style="background:#c7c7c7;">#c7c7c7</div>
 * <div style="background:#bcbd22;">#bcbd22</div>
 * <div style="background:#dbdb8d;">#dbdb8d</div>
 * <div style="background:#17becf;">#17becf</div>
 * <div style="background:#9edae5;">#9edae5</div>
 *
 * @param {number...} domain... domain values.
 * @returns {pv.Scale.ordinal} a new ordinal color scale.
 * @see pv.color
*/
pv.Colors.category20 = function() {
  var scale = pv.colors(
      "#1f77b4", "#aec7e8", "#ff7f0e", "#ffbb78", "#2ca02c",
      "#98df8a", "#d62728", "#ff9896", "#9467bd", "#c5b0d5",
      "#8c564b", "#c49c94", "#e377c2", "#f7b6d2", "#7f7f7f",
      "#c7c7c7", "#bcbd22", "#dbdb8d", "#17becf", "#9edae5");
  scale.domain.apply(scale, arguments);
  return scale;
};

/**
 * Returns a new alternative 19-color scheme. The arguments to this constructor
 * are optional, and equivalent to calling
 * {@link pv.Scale.OrdinalScale#domain}. The following colors are used:
 *
 * <div style="background:#9c9ede;">#9c9ede</div>
 * <div style="background:#7375b5;">#7375b5</div>
 * <div style="background:#4a5584;">#4a5584</div>
 * <div style="background:#cedb9c;">#cedb9c</div>
 * <div style="background:#b5cf6b;">#b5cf6b</div>
 * <div style="background:#8ca252;">#8ca252</div>
 * <div style="background:#637939;">#637939</div>
 * <div style="background:#e7cb94;">#e7cb94</div>
 * <div style="background:#e7ba52;">#e7ba52</div>
 * <div style="background:#bd9e39;">#bd9e39</div>
 * <div style="background:#8c6d31;">#8c6d31</div>
 * <div style="background:#e7969c;">#e7969c</div>
 * <div style="background:#d6616b;">#d6616b</div>
 * <div style="background:#ad494a;">#ad494a</div>
 * <div style="background:#843c39;">#843c39</div>
 * <div style="background:#de9ed6;">#de9ed6</div>
 * <div style="background:#ce6dbd;">#ce6dbd</div>
 * <div style="background:#a55194;">#a55194</div>
 * <div style="background:#7b4173;">#7b4173</div>
 *
 * @param {number...} domain... domain values.
 * @returns {pv.Scale.ordinal} a new ordinal color scale.
 * @see pv.color
 */
pv.Colors.category19 = function() {
  var scale = pv.colors(
      "#9c9ede", "#7375b5", "#4a5584", "#cedb9c", "#b5cf6b",
      "#8ca252", "#637939", "#e7cb94", "#e7ba52", "#bd9e39",
      "#8c6d31", "#e7969c", "#d6616b", "#ad494a", "#843c39",
      "#de9ed6", "#ce6dbd", "#a55194", "#7b4173");
  scale.domain.apply(scale, arguments);
  return scale;
};