Sankey from CSV by harrystevens

index.html

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

      body {
        margin: 0;
        font-family: "Helvetica Neue", sans-serif;
      }

      .node rect {
        cursor: move;
        fill-opacity: .9;
        shape-rendering: crispEdges;
      }
      .node text {
        pointer-events: none;
        text-shadow: 0px 0px 2px #fff;
        font-size: .8em;
      }

      .link {
        fill: none;
        stroke: #000;
        stroke-opacity: .2;
      }
      .link:hover {
        stroke-opacity: .5;
      }

    </style>
  </head>
  <body>
    <script src="https://d3js.org/d3.v4.min.js"></script>
    <script src="sankey.js"></script>
   
    <script>
      // set the dimensions and margins of the graph
      var margin = {top: 10, right: 10, bottom: 10, left: 10},
          width = window.innerWidth - margin.left - margin.right,
          height = window.innerHeight - margin.top - margin.bottom;

      // format variables
      var formatNumber = d3.format(",.0f"),    // zero decimal places
          format = function(d) { return "$" + formatNumber(d); },
          color = d3.scaleOrdinal(d3.schemeCategory20);

      // append the svg object to the body of the page
      var svg = d3.select("body").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(10)
          .nodePadding(10)
          .size([width, height]);

      var path = sankey.link();

      // load the data
      d3.queue()
          .defer(d3.csv, "data.csv")
          .await(ready);

      function ready(error, csv){

        // create an array to push all sources and targets, before making them unique
        var arr = [];
        csv.forEach(function(d){

          arr.push(d.source);
          arr.push(d.target);

        });

        // create nodes array
        var nodes = arr.filter(onlyUnique).map(function(d,i){
          return {
            node: i,
            name: d
          }
        });

        // create links array
        var links = csv.map(function(csv_row){
          return {
            source: getNode("source"),
            target: getNode("target"),
            value: +csv_row.value
          }

          function getNode(type){
            return nodes.filter(function(node_object){ return node_object.name == csv_row[type]; })[0].node;
          }

        });

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

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

        // add the rectangles for the nodes
        node.append("rect")
            .attr("height", function(d) { return d.dy < 0 ? .1 : d.dy; })
            .attr("width", sankey.nodeWidth())
            .style("fill", function(d) { 
              return d.color = color(d.name.replace(/ .*/, "")); 
            })
            .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 + "," 
                     + (d.y = Math.max(
                        0, Math.min(height - d.dy, d3.event.y))
                       ) + ")");
          sankey.relayout();
          link.attr("d", path);
        }

      }

      // unique values of an array
      function onlyUnique(value, index, self) { 
          return self.indexOf(value) === index;
      }

    </script>
  </body>
</html>

data.csv

source,target,value
Bob,Jimmy,30000000
Joey,Bunk,632000000
Joey,Lester,100000000
Joey,Kima,541000000
Joey,Sidnor,7500000
Joey,Roland,15000000
Joey,Cedric,20000000
Steve,Kima,30000000
Steve,Cedric,10000000
Ross,Jay,15384115
Ross,Bunk,21000034
Ross,Lester,52563320
Ross,Kima,99039298
Ross,Phoebe,5910000
Ross,Sidnor,18872439
Ross,Chandler,6797000
Ross,Cedric,13105704
John,Bunk,1072500000
John,Lester,2500000
John,Kima,187500000
John,Phoebe,10000000
John,Monica,10000000
John,Chandler,10000000
John,Rachel,10000000
Tim,Bunk,20000000
Tim,Rachel,10000000

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) {
          if (nextNodes.indexOf(link.target) < 0) {
            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;
};