d3noob/.block

## .block
license: mit

## README.md

      
    Raw
  

              README.md
            
          
    The above example is intended to demonstrate drawing a simple Sankey diagram using JSON with names for the nodes instead of relying on d3 to index them. It uses  Jason Davies' version of the Sankey plugin.
This is one of the code samples for the update to the book D3 Tips and Tricks to version 5 of d3.js.

  
## index.html
<!DOCTYPE html>
<meta charset="utf-8">
<title>SANKEY Experiment</title>
<style>

.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;
}

</style>
<body>

<script src="https://d3js.org/d3.v5.min.js"></script>
<script src="sankey.js"></script>
<script>

var units = "Widgets";

// set the dimensions and margins of the graph
var margin = {top: 10, right: 10, bottom: 10, left: 10},
    width = 700 - margin.left - margin.right,
    height = 300 - margin.top - margin.bottom;

// format variables
var formatNumber = d3.format(",.0f"),    // zero decimal places
    format = function(d) { return formatNumber(d) + " " + units; },
    color = d3.scaleOrdinal(d3.schemeCategory10);

// 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(36)
    .nodePadding(40)
    .size([width, height]);

var path = sankey.link();

// load the data
d3.json("sankey-names.json").then(function(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.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; })
      .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);
  }
});

</script>

</body>


## sankey-names.json
{
"nodes":[
{"name":"Barry"},
{"name":"Frodo"},
{"name":"Elvis"},
{"name":"Sarah"},
{"name":"Alice"}
],
"links":[
{"source":"Barry","target":"Elvis","value":2},
{"source":"Frodo","target":"Elvis","value":2},
{"source":"Frodo","target":"Sarah","value":2},
{"source":"Barry","target":"Alice","value":2},
{"source":"Elvis","target":"Sarah","value":2},
{"source":"Elvis","target":"Alice","value":2},
{"source":"Sarah","target":"Alice","value":4}
]}

## 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;
};

## thumbnail.png

      
    Raw
  

              thumbnail.png
	<!DOCTYPE html>
	<meta charset="utf-8">
	<title>SANKEY Experiment</title>
	<style>

	.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;
	}

	</style>
	<body>

	<script src="https://d3js.org/d3.v5.min.js"></script>
	<script src="sankey.js"></script>
	<script>

	var units = "Widgets";

	// set the dimensions and margins of the graph
	var margin = {top: 10, right: 10, bottom: 10, left: 10},
	width = 700 - margin.left - margin.right,
	height = 300 - margin.top - margin.bottom;

	// format variables
	var formatNumber = d3.format(",.0f"), // zero decimal places
	format = function(d) { return formatNumber(d) + " " + units; },
	color = d3.scaleOrdinal(d3.schemeCategory10);

	// 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(36)
	.nodePadding(40)
	.size([width, height]);

	var path = sankey.link();

	// load the data
	d3.json("sankey-names.json").then(function(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.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; })
	.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);
	}
	});

	</script>

	</body>
	{
	"nodes":[
	{"name":"Barry"},
	{"name":"Frodo"},
	{"name":"Elvis"},
	{"name":"Sarah"},
	{"name":"Alice"}
	],
	"links":[
	{"source":"Barry","target":"Elvis","value":2},
	{"source":"Frodo","target":"Elvis","value":2},
	{"source":"Frodo","target":"Sarah","value":2},
	{"source":"Barry","target":"Alice","value":2},
	{"source":"Elvis","target":"Sarah","value":2},
	{"source":"Elvis","target":"Alice","value":2},
	{"source":"Sarah","target":"Alice","value":4}
	]}
	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;
	};