src/models/parallelCoordinates.js

//Code adapted from Jason Davies' "Parallel Coordinates"
// http://bl.ocks.org/jasondavies/1341281

nv.models.parallelCoordinates = function() {
  "use strict";
  //============================================================
  // Public Variables with Default Settings
  //------------------------------------------------------------


  var margin = {top: 30, right: 10, bottom: 10, left: 10}
    , width = 960
    , height = 500
    , x = d3.scale.ordinal()
    , y = {}
    , dimensions = []
    , color = nv.utils.getColor(d3.scale.category20c().range())
    , axisLabel = function(d) { return d; }
    , filters = []
    , active = []
    , dispatch = d3.dispatch('brush')
    ;

  //============================================================


  //============================================================
  // Private Variables
  //------------------------------------------------------------


  //============================================================


  function chart(selection) {
    selection.each(function(data) {
      var availableWidth = width - margin.left - margin.right,
          availableHeight = height - margin.top - margin.bottom,
          container = d3.select(this);

      active = data; //set all active before first brush call

      chart.update = function() { }; //This is a placeholder until this chart is made resizeable

      //------------------------------------------------------------
      // Setup Scales

      x
        .rangePoints([0, availableWidth], 1)
        .domain(dimensions);

      // Extract the list of dimensions and create a scale for each.
      dimensions.forEach(function(d) {
          y[d] = d3.scale.linear()
              .domain(d3.extent(data, function(p) { return +p[d]; }))
              .range([availableHeight, 0]);

          y[d].brush = d3.svg.brush().y(y[d]).on('brush', brush);

          return d != 'name';
        })


      //------------------------------------------------------------


      //------------------------------------------------------------
      // Setup containers and skeleton of chart

      var wrap = container.selectAll('g.nv-wrap.nv-parallelCoordinates').data([data]);
      var wrapEnter = wrap.enter().append('g').attr('class', 'nvd3 nv-wrap nv-parallelCoordinates');
      var gEnter = wrapEnter.append('g');
      var g = wrap.select('g')

      gEnter.append('g').attr('class', 'nv-parallelCoordinatesWrap');

      wrap.attr('transform', 'translate(' + margin.left + ',' + margin.top + ')');

      //------------------------------------------------------------


      var line = d3.svg.line(),
          axis = d3.svg.axis().orient('left'),
          background,
          foreground;


      // Add grey background lines for context.
      background = gEnter.append('g')
          .attr('class', 'background')
        .selectAll('path')
          .data(data)
        .enter().append('path')
          .attr('d', path)
        ;

      // Add blue foreground lines for focus.
      foreground = gEnter.append('g')
          .attr('class', 'foreground')
        .selectAll('path')
          .data(data)
        .enter().append('path')
          .attr('d', path)
        ;

      // Add a group element for each dimension.
      var dimension = g.selectAll('.dimension')
          .data(dimensions)
        .enter().append('g')
          .attr('class', 'dimension')
          .attr('transform', function(d) { return 'translate(' + x(d) + ',0)'; });

      // Add an axis and title.
      dimension.append('g')
          .attr('class', 'axis')
          .each(function(d) { d3.select(this).call(axis.scale(y[d])); })
        .append('text')
          .attr('text-anchor', 'middle')
          .attr('y', -9)
          .text(String);

      // Add and store a brush for each axis.
      dimension.append('g')
          .attr('class', 'brush')
          .each(function(d) { d3.select(this).call(y[d].brush); })
        .selectAll('rect')
          .attr('x', -8)
          .attr('width', 16);


      // Returns the path for a given data point.
      function path(d) {
        return line(dimensions.map(function(p) { return [x(p), y[p](d[p])]; }));
      }

      // Handles a brush event, toggling the display of foreground lines.
      function brush() {
        var actives = dimensions.filter(function(p) { return !y[p].brush.empty(); }),
            extents = actives.map(function(p) { return y[p].brush.extent(); });

        filters = []; //erase current filters
        actives.forEach(function(d,i) {
          filters[i] = {
            dimension: d,
            extent: extents[i]
          }
        });

        active = []; //erase current active list
        foreground.style('display', function(d) {
          var isActive = actives.every(function(p, i) {
            return extents[i][0] <= d[p] && d[p] <= extents[i][1];
          });
          if (isActive) active.push(d);
          return isActive ? null : 'none';
        });

        dispatch.brush({
          filters: filters,
          active: active
        });

      }



    });

    return chart;
  }


  //============================================================
  // Expose Public Variables
  //------------------------------------------------------------


  chart.dispatch = dispatch;
  chart.options = nv.utils.optionsFunc.bind(chart);
  
  chart.margin = function(_) {
    if (!arguments.length) return margin;
    margin.top    = typeof _.top    != 'undefined' ? _.top    : margin.top;
    margin.right  = typeof _.right  != 'undefined' ? _.right  : margin.right;
    margin.bottom = typeof _.bottom != 'undefined' ? _.bottom : margin.bottom;
    margin.left   = typeof _.left   != 'undefined' ? _.left   : margin.left;
    return chart;
  };

  chart.width = function(_) {
    if (!arguments.length) return width;
    width = _;
    return chart;
  };

  chart.height = function(_) {
    if (!arguments.length) return height;
    height = _;
    return chart;
  };

  chart.color = function(_) {
    if (!arguments.length) return color;
    color = nv.utils.getColor(_)
    return chart;
  };

  chart.xScale = function(_) {
    if (!arguments.length) return x;
    x = _;
    return chart;
  };

  chart.yScale = function(_) {
    if (!arguments.length) return y;
    y = _;
    return chart;
  };

  chart.dimensions = function(_) {
    if (!arguments.length) return dimensions;
    dimensions = _;
    return chart;
  };

  chart.filters = function() {
    return filters;
  };

  chart.active = function() {
    return active;
  };

  //============================================================


  return chart;
}