Color links same as origin nodes for a d3 sankey plot

Question

I have a sankey plot and I have been able to change the node color by adding a color key:value pair into my json object, now I trying to do the same for my links. My thought was I could do the same i.e. add a color key:value pair to my links with the origin color, then I would be able to color the links the same as their origin node.

Below is my json object. You can see that the color for each link matches the color for the node where links.source = nodes.name.

I was able to get the nodes colored based on the color in the node section of the json object by modifying the line where I commented \ modified node color.

Though it seems that this same strategy doesn't work for the links? Maybe it does? Does anyone have thoughts on how color the links like I'm describing?

JSON

{
 "links": [
  {
   "color": "#00A651", 
   "source": "IPhone ", 
   "target": "Android Mobile", 
   "value": "2152.0"
  }, 
  {
   "color": "#D2232A", 
   "source": "Windows Mobile ", 
   "target": "Android Tablet", 
   "value": "5.0"
  }, 
  {
   "color": "#CBC911", 
   "source": "Android Tablet ", 
   "target": "IPad", 
   "value": "102.0"
  }, 
  {
   "color": "#0092D0", 
   "source": "Android Mobile ", 
   "target": "Computer", 
   "value": "26005.0"
  }, 
  {
   "color": "#B95EA4", 
   "source": "Computer ", 
   "target": "Android Tablet", 
   "value": "7681.0"
  }, 
  {
   "color": "#D2232A", 
   "source": "Windows Mobile ", 
   "target": "IPhone", 
   "value": "23.0"
  }, 
  {
   "color": "#0092D0", 
   "source": "Android Mobile ", 
   "target": "Android Mobile", 
   "value": "24634.3"
  }, 
  {
   "color": "#B95EA4", 
   "source": "Computer ", 
   "target": "Android Mobile", 
   "value": "29165.0"
  }, 
  {
   "color": "#00A651", 
   "source": "IPhone ", 
   "target": "IPad", 
   "value": "1312.0"
  }, 
  {
   "color": "#F79131", 
   "source": "IPad ", 
   "target": "Android Mobile", 
   "value": "576.0"
  }, 
  {
   "color": "#0092D0", 
   "source": "Android Mobile ", 
   "target": "Android Tablet", 
   "value": "209.0"
  }, 
  {
   "color": "#D2232A", 
   "source": "Windows Mobile ", 
   "target": "Windows Mobile", 
   "value": "2007.0"
  }, 
  {
   "color": "#CBC911", 
   "source": "Android Tablet ", 
   "target": "Windows Mobile", 
   "value": "1.0"
  }, 
  {
   "color": "#00A651", 
   "source": "IPhone ", 
   "target": "Computer", 
   "value": "21400.0"
  }, 
  {
   "color": "#B95EA4", 
   "source": "Computer ", 
   "target": "IPhone", 
   "value": "40140.0"
  }, 
  {
   "color": "#CBC911", 
   "source": "Android Tablet ", 
   "target": "Computer", 
   "value": "7234.0"
  }, 
  {
   "color": "#0092D0", 
   "source": "Android Mobile ", 
   "target": "IPad", 
   "value": "210.0"
  }, 
  {
   "color": "#0092D0", 
   "source": "Android Mobile ", 
   "target": "Windows Mobile", 
   "value": "10.0"
  }, 
  {
   "color": "#F79131", 
   "source": "IPad ", 
   "target": "IPad", 
   "value": "20216.0"
  }, 
  {
   "color": "#00A651", 
   "source": "IPhone ", 
   "target": "Android Tablet", 
   "value": "201.0"
  }, 
  {
   "color": "#F79131", 
   "source": "IPad ", 
   "target": "Windows Mobile", 
   "value": "17.0"
  }, 
  {
   "color": "#B95EA4", 
   "source": "Computer ", 
   "target": "Windows Mobile", 
   "value": "843.0"
  }, 
  {
   "color": "#D2232A", 
   "source": "Windows Mobile ", 
   "target": "Computer", 
   "value": "2468.0"
  }, 
  {
   "color": "#00A651", 
   "source": "IPhone ", 
   "target": "Windows Mobile", 
   "value": "40.0"
  }, 
  {
   "color": "#F79131", 
   "source": "IPad ", 
   "target": "IPhone", 
   "value": "1194.0"
  }, 
  {
   "color": "#D2232A", 
   "source": "Windows Mobile ", 
   "target": "IPad", 
   "value": "22.0"
  }, 
  {
   "color": "#CBC911", 
   "source": "Android Tablet ", 
   "target": "Android Mobile", 
   "value": "426.0"
  }, 
  {
   "color": "#F79131", 
   "source": "IPad ", 
   "target": "Android Tablet", 
   "value": "57.0"
  }, 
  {
   "color": "#B95EA4", 
   "source": "Computer ", 
   "target": "IPad", 
   "value": "40995.0"
  }, 
  {
   "color": "#0092D0", 
   "source": "Android Mobile ", 
   "target": "IPhone", 
   "value": "259.0"
  }, 
  {
   "color": "#CBC911", 
   "source": "Android Tablet ", 
   "target": "IPhone", 
   "value": "202.0"
  }, 
  {
   "color": "#D2232A", 
   "source": "Windows Mobile ", 
   "target": "Android Mobile", 
   "value": "152.0"
  }, 
  {
   "color": "#CBC911", 
   "source": "Android Tablet ", 
   "target": "Android Tablet", 
   "value": "4681.0"
  }, 
  {
   "color": "#F79131", 
   "source": "IPad ", 
   "target": "Computer", 
   "value": "20344.0"
  }, 
  {
   "color": "#00A651", 
   "source": "IPhone ", 
   "target": "IPhone", 
   "value": "115632.0"
  }
 ], 
 "nodes": [
  {
   "color": "#0092D0", 
   "name": "Android Mobile"
  }, 
  {
   "color": "#0092D0", 
   "name": "Android Mobile "
  }, 
  {
   "color": "#CBC911", 
   "name": "Android Tablet"
  }, 
  {
   "color": "#CBC911", 
   "name": "Android Tablet "
  }, 
  {
   "color": "#B95EA4", 
   "name": "Computer"
  }, 
  {
   "color": "#B95EA4", 
   "name": "Computer "
  }, 
  {
   "color": "#F79131", 
   "name": "IPad"
  }, 
  {
   "color": "#F79131", 
   "name": "IPad "
  }, 
  {
   "color": "#00A651", 
   "name": "IPhone"
  }, 
  {
   "color": "#00A651", 
   "name": "IPhone "
  }, 
  {
   "color": "#D2232A", 
   "name": "Windows Mobile"
  }, 
  {
   "color": "#D2232A", 
   "name": "Windows Mobile "
  }
 ]
}

INDEX.HTML

<!DOCTYPE html>
<meta charset="utf-8">
<script>

.node rect {
  cursor: move;
  fill-opacity: .9;
  shape-rendering: crispEdges;
}

.node text {
  pointer-events: none;
  text-shadow: 0 1px 0 #fff;
}

.link {
  fill: none;
  stroke: #000;
  stroke-opacity: .2;
}

.link:hover {
  stroke-opacity: .5;
}

</script>

<body>

<p id="chart">

<script src="http://d3js.org/d3.v3.js"></script>
<script src="sankey.js"></script>
<script>

var units = "ABC";

var margin = {top: 10, right: 10, bottom: 10, left: 10},
    width = 1200 - margin.left - margin.right,
    height = 740 - margin.top - margin.bottom;

var formatNumber = d3.format(",.0f"),    // zero decimal places
    format = function(d) { return formatNumber(d) + " " + units; },
    color = d3.scale.category10();

// append the svg canvas to the page
var svg = d3.select("#chart").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", 
          "translate(" + margin.left + "," + margin.top + ")");

// Set the sankey diagram properties
var sankey = d3.sankey()
    .nodeWidth(36)
    .nodePadding(10)
    .size([width, height]);

var path = sankey.link();

// load the data
d3.json("xd_json.json", function(error, graph) {

    var nodeMap = {};
    graph.nodes.forEach(function(x) { nodeMap[x.name] = x; });
    graph.links = graph.links.map(function(x) {
      return {
        source: nodeMap[x.source],
        target: nodeMap[x.target],
        value: x.value
      };
    });

  sankey
      .nodes(graph.nodes)
      .links(graph.links)
      .layout(32);

// add in the links
  var link = svg.append("g").selectAll(".link")
      .data(graph.links)
    .enter().append("path")
      .attr("class", "link")
      .attr("d", path)
      .style("stroke-width", function(d) { return Math.max(1, d.dy); })
      .sort(function(a, b) { return b.dy - a.dy; });

// add the link titles
  link.append("title")
        .text(function(d) {
        return d.source.name + " → " + 
                d.target.name + "\n" + format(d.value); });

// add in the nodes
  var node = svg.append("g").selectAll(".node")
      .data(graph.nodes)
    .enter().append("g")
      .attr("class", "node")
      .attr("transform", function(d) { 
      return "translate(" + d.x + "," + d.y + ")"; })
    .call(d3.behavior.drag()
      .origin(function(d) { return d; })
      .on("dragstart", function() { 
      this.parentNode.appendChild(this); })
      .on("drag", dragmove));

// add the rectangles for the nodes
  node.append("rect")
      .attr("height", function(d) { return d.dy; })
      .attr("width", sankey.nodeWidth())
      .style("fill", function(d) { return d.color;}) // modified node color
      .style("stroke", function(d) { 
        return d3.rgb(d.color).darker(2); })
    .append("title")
      .text(function(d) { 
        return d.name + "\n" + format(d.value); });

// add in the title for the nodes
  node.append("text")
      .attr("x", -6)
      .attr("y", function(d) { return d.dy / 2; })
      .attr("dy", ".35em")
      .attr("text-anchor", "end")
      .attr("transform", null)
      .text(function(d) { return d.name; })
    .filter(function(d) { return d.x < width / 2; })
      .attr("x", 6 + sankey.nodeWidth())
      .attr("text-anchor", "start");

// the function for moving the nodes
  function dragmove(d) {
    d3.select(this).attr("transform", 
        "translate(" + (
             d.x = Math.max(0, Math.min(width - d.dx, d3.event.x))
          ) + "," + (
                   d.y = Math.max(0, Math.min(height - d.dy, d3.event.y))
            ) + ")");
    sankey.relayout();
    link.attr("d", path);
  }
});

</script>

</body>
</html>

SANKEY.JS

d3.sankey = function() {
  var sankey = {},
      nodeWidth = 24,
      nodePadding = 8,
      size = [1, 1],
      nodes = [],
      links = [];

  sankey.nodeWidth = function(_) {
    if (!arguments.length) return nodeWidth;
    nodeWidth = +_;
    return sankey;
  };

  sankey.nodePadding = function(_) {
    if (!arguments.length) return nodePadding;
    nodePadding = +_;
    return sankey;
  };

  sankey.nodes = function(_) {
    if (!arguments.length) return nodes;
    nodes = _;
    return sankey;
  };

  sankey.links = function(_) {
    if (!arguments.length) return links;
    links = _;
    return sankey;
  };

  sankey.size = function(_) {
    if (!arguments.length) return size;
    size = _;
    return sankey;
  };

  sankey.layout = function(iterations) {
    computeNodeLinks();
    computeNodeValues();
    computeNodeBreadths();
    computeNodeDepths(iterations);
    computeLinkDepths();
    return sankey;
  };

  sankey.relayout = function() {
    computeLinkDepths();
    return sankey;
  };

  sankey.link = function() {
    var curvature = .5;

    function link(d) {
      var x0 = d.source.x + d.source.dx,
          x1 = d.target.x,
          xi = d3.interpolateNumber(x0, x1),
          x2 = xi(curvature),
          x3 = xi(1 - curvature),
          y0 = d.source.y + d.sy + d.dy / 2,
          y1 = d.target.y + d.ty + d.dy / 2;
      return "M" + x0 + "," + y0
           + "C" + x2 + "," + y0
           + " " + x3 + "," + y1
           + " " + x1 + "," + y1;
    }

    link.curvature = function(_) {
      if (!arguments.length) return curvature;
      curvature = +_;
      return link;
    };

    return link;
  };

  // Populate the sourceLinks and targetLinks for each node.
  // Also, if the source and target are not objects, assume they are indices.
  function computeNodeLinks() {
    nodes.forEach(function(node) {
      node.sourceLinks = [];
      node.targetLinks = [];
    });
    links.forEach(function(link) {
      var source = link.source,
          target = link.target;
      if (typeof source === "number") source = link.source = nodes[link.source];
      if (typeof target === "number") target = link.target = nodes[link.target];
      source.sourceLinks.push(link);
      target.targetLinks.push(link);
    });
  }

  // Compute the value (size) of each node by summing the associated links.
  function computeNodeValues() {
    nodes.forEach(function(node) {
      node.value = Math.max(
        d3.sum(node.sourceLinks, value),
        d3.sum(node.targetLinks, value)
      );
    });
  }

  // Iteratively assign the breadth (x-position) for each node.
  // Nodes are assigned the maximum breadth of incoming neighbors plus one;
  // nodes with no incoming links are assigned breadth zero, while
  // nodes with no outgoing links are assigned the maximum breadth.
  function computeNodeBreadths() {
    var remainingNodes = nodes,
        nextNodes,
        x = 0;

    while (remainingNodes.length) {
      nextNodes = [];
      remainingNodes.forEach(function(node) {
        node.x = x;
        node.dx = nodeWidth;
        node.sourceLinks.forEach(function(link) {
          nextNodes.push(link.target);
        });
      });
      remainingNodes = nextNodes;
      ++x;
    }

    //
    moveSinksRight(x);
    scaleNodeBreadths((size[0] - nodeWidth) / (x - 1));
  }

  function moveSourcesRight() {
    nodes.forEach(function(node) {
      if (!node.targetLinks.length) {
        node.x = d3.min(node.sourceLinks, function(d) { return d.target.x; }) - 1;
      }
    });
  }

  function moveSinksRight(x) {
    nodes.forEach(function(node) {
      if (!node.sourceLinks.length) {
        node.x = x - 1;
      }
    });
  }

  function scaleNodeBreadths(kx) {
    nodes.forEach(function(node) {
      node.x *= kx;
    });
  }

  function computeNodeDepths(iterations) {
    var nodesByBreadth = d3.nest()
        .key(function(d) { return d.x; })
        .sortKeys(d3.ascending)
        .entries(nodes)
        .map(function(d) { return d.values; });

    //
    initializeNodeDepth();
    resolveCollisions();
    for (var alpha = 1; iterations > 0; --iterations) {
      relaxRightToLeft(alpha *= .99);
      resolveCollisions();
      relaxLeftToRight(alpha);
      resolveCollisions();
    }

    function initializeNodeDepth() {
      var ky = d3.min(nodesByBreadth, function(nodes) {
        return (size[1] - (nodes.length - 1) * nodePadding) / d3.sum(nodes, value);
      });

      nodesByBreadth.forEach(function(nodes) {
        nodes.forEach(function(node, i) {
          node.y = i;
          node.dy = node.value * ky;
        });
      });

      links.forEach(function(link) {
        link.dy = link.value * ky;
      });
    }

    function relaxLeftToRight(alpha) {
      nodesByBreadth.forEach(function(nodes, breadth) {
        nodes.forEach(function(node) {
          if (node.targetLinks.length) {
            var y = d3.sum(node.targetLinks, weightedSource) / d3.sum(node.targetLinks, value);
            node.y += (y - center(node)) * alpha;
          }
        });
      });

      function weightedSource(link) {
        return center(link.source) * link.value;
      }
    }

    function relaxRightToLeft(alpha) {
      nodesByBreadth.slice().reverse().forEach(function(nodes) {
        nodes.forEach(function(node) {
          if (node.sourceLinks.length) {
            var y = d3.sum(node.sourceLinks, weightedTarget) / d3.sum(node.sourceLinks, value);
            node.y += (y - center(node)) * alpha;
          }
        });
      });

      function weightedTarget(link) {
        return center(link.target) * link.value;
      }
    }

    function resolveCollisions() {
      nodesByBreadth.forEach(function(nodes) {
        var node,
            dy,
            y0 = 0,
            n = nodes.length,
            i;

        // Push any overlapping nodes down.
        nodes.sort(ascendingDepth);
        for (i = 0; i < n; ++i) {
          node = nodes[i];
          dy = y0 - node.y;
          if (dy > 0) node.y += dy;
          y0 = node.y + node.dy + nodePadding;
        }

        // If the bottommost node goes outside the bounds, push it back up.
        dy = y0 - nodePadding - size[1];
        if (dy > 0) {
          y0 = node.y -= dy;

          // Push any overlapping nodes back up.
          for (i = n - 2; i >= 0; --i) {
            node = nodes[i];
            dy = node.y + node.dy + nodePadding - y0;
            if (dy > 0) node.y -= dy;
            y0 = node.y;
          }
        }
      });
    }

    function ascendingDepth(a, b) {
      return a.y - b.y;
    }
  }

  function computeLinkDepths() {
    nodes.forEach(function(node) {
      node.sourceLinks.sort(ascendingTargetDepth);
      node.targetLinks.sort(ascendingSourceDepth);
    });
    nodes.forEach(function(node) {
      var sy = 0, ty = 0;
      node.sourceLinks.forEach(function(link) {
        link.sy = sy;
        sy += link.dy;
      });
      node.targetLinks.forEach(function(link) {
        link.ty = ty;
        ty += link.dy;
      });
    });

    function ascendingSourceDepth(a, b) {
      return a.source.y - b.source.y;
    }

    function ascendingTargetDepth(a, b) {
      return a.target.y - b.target.y;
    }
  }

  function center(node) {
    return node.y + node.dy / 2;
  }

  function value(link) {
    return link.value;
  }

  return sankey;
};

Answer 1

No problem, I was able to set it up:

Two lines of change:

Add the stroke color

  var link = svg.append("g").selectAll(".link")
      .data(graph.links)
    .enter().append("path")
      .attr("class", "link")
      .attr("d", path)
      .style("stroke", function(d){return d.color;})//add this to return the color of link
      .style("stroke-width", function(d) { return Math.max(1, d.dy); })
      .sort(function(a, b) { return b.dy - a.dy; });

Next change add color to the link JSON object

graph.links = graph.links.map(function(x) {
  return {
    source: nodeMap[x.source],
    target: nodeMap[x.target],
    value: x.value,
    color: x.color //get the color in the json fo links
  };
});

Full working code here

Hope this helps!