sankeyLayout.js

var layout = require("../../util/layout");

var nest = require("../../util/array/nest");

var zrUtil = require("zrender/lib/core/util");

var _config = require("../../config");

var __DEV__ = _config.__DEV__;

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License.  You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied.  See the License for the
* specific language governing permissions and limitations
* under the License.
*/

/**
 * @file The layout algorithm of sankey view
 * @author Deqing Li(annong035@gmail.com)
 */
function _default(ecModel, api, payload) {
  ecModel.eachSeriesByType('sankey', function (seriesModel) {
    var nodeWidth = seriesModel.get('nodeWidth');
    var nodeGap = seriesModel.get('nodeGap');
    var layoutInfo = getViewRect(seriesModel, api);
    seriesModel.layoutInfo = layoutInfo;
    var width = layoutInfo.width;
    var height = layoutInfo.height;
    var graph = seriesModel.getGraph();
    var nodes = graph.nodes;
    var edges = graph.edges;
    computeNodeValues(nodes);
    var filteredNodes = zrUtil.filter(nodes, function (node) {
      return node.getLayout().value === 0;
    });
    var iterations = filteredNodes.length !== 0 ? 0 : seriesModel.get('layoutIterations');
    layoutSankey(nodes, edges, nodeWidth, nodeGap, width, height, iterations);
  });
}
/**
 * Get the layout position of the whole view
 *
 * @param {module:echarts/model/Series} seriesModel  the model object of sankey series
 * @param {module:echarts/ExtensionAPI} api  provide the API list that the developer can call
 * @return {module:zrender/core/BoundingRect}  size of rect to draw the sankey view
 */


function getViewRect(seriesModel, api) {
  return layout.getLayoutRect(seriesModel.getBoxLayoutParams(), {
    width: api.getWidth(),
    height: api.getHeight()
  });
}

function layoutSankey(nodes, edges, nodeWidth, nodeGap, width, height, iterations) {
  computeNodeBreadths(nodes, edges, nodeWidth, width);
  computeNodeDepths(nodes, edges, height, nodeGap, iterations);
  computeEdgeDepths(nodes);
}
/**
 * Compute the value of each node by summing the associated edge's value
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 */


function computeNodeValues(nodes) {
  zrUtil.each(nodes, function (node) {
    var value1 = sum(node.outEdges, getEdgeValue);
    var value2 = sum(node.inEdges, getEdgeValue);
    var value = Math.max(value1, value2);
    node.setLayout({
      value: value
    }, true);
  });
}
/**
 * Compute the x-position for each node.
 * 
 * Here we use Kahn algorithm to detect cycle when we traverse
 * the node to computer the initial x position.
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 * @param  {number} nodeWidth  the dx of the node
 * @param  {number} width  the whole width of the area to draw the view
 */


function computeNodeBreadths(nodes, edges, nodeWidth, width) {
  // Used to mark whether the edge is deleted. if it is deleted,
  // the value is 0, otherwise it is 1.
  var remainEdges = []; // Storage each node's indegree.

  var indegreeArr = []; //Used to storage the node with indegree is equal to 0.

  var zeroIndegrees = [];
  var nextNode = [];
  var x = 0;
  var kx = 0;

  for (var i = 0; i < edges.length; i++) {
    remainEdges[i] = 1;
  }

  for (var i = 0; i < nodes.length; i++) {
    indegreeArr[i] = nodes[i].inEdges.length;

    if (indegreeArr[i] === 0) {
      zeroIndegrees.push(nodes[i]);
    }
  }

  while (zeroIndegrees.length) {
    zrUtil.each(zeroIndegrees, function (node) {
      node.setLayout({
        x: x
      }, true);
      node.setLayout({
        dx: nodeWidth
      }, true);
      zrUtil.each(node.outEdges, function (edge) {
        var indexEdge = edges.indexOf(edge);
        remainEdges[indexEdge] = 0;
        var targetNode = edge.node2;
        var nodeIndex = nodes.indexOf(targetNode);

        if (--indegreeArr[nodeIndex] === 0) {
          nextNode.push(targetNode);
        }
      });
    });
    ++x;
    zeroIndegrees = nextNode;
    nextNode = [];
  }

  for (var i = 0; i < remainEdges.length; i++) {}

  moveSinksRight(nodes, x);
  kx = (width - nodeWidth) / (x - 1);
  scaleNodeBreadths(nodes, kx);
}
/**
 * All the node without outEgdes are assigned maximum x-position and
 *     be aligned in the last column.
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 * @param {number} x  value (x-1) use to assign to node without outEdges
 *     as x-position
 */


function moveSinksRight(nodes, x) {
  zrUtil.each(nodes, function (node) {
    if (!node.outEdges.length) {
      node.setLayout({
        x: x - 1
      }, true);
    }
  });
}
/**
 * Scale node x-position to the width
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 * @param {number} kx   multiple used to scale nodes
 */


function scaleNodeBreadths(nodes, kx) {
  zrUtil.each(nodes, function (node) {
    var nodeX = node.getLayout().x * kx;
    node.setLayout({
      x: nodeX
    }, true);
  });
}
/**
 * Using Gauss-Seidel iterations method to compute the node depth(y-position)
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 * @param {module:echarts/data/Graph~Edge} edges  edge of sankey view
 * @param {number} height  the whole height of the area to draw the view
 * @param {number} nodeGap  the vertical distance between two nodes
 *     in the same column.
 * @param {number} iterations  the number of iterations for the algorithm
 */


function computeNodeDepths(nodes, edges, height, nodeGap, iterations) {
  var nodesByBreadth = nest().key(function (d) {
    return d.getLayout().x;
  }).sortKeys(ascending).entries(nodes).map(function (d) {
    return d.values;
  });
  initializeNodeDepth(nodes, nodesByBreadth, edges, height, nodeGap);
  resolveCollisions(nodesByBreadth, nodeGap, height);

  for (var alpha = 1; iterations > 0; iterations--) {
    // 0.99 is a experience parameter, ensure that each iterations of
    // changes as small as possible.
    alpha *= 0.99;
    relaxRightToLeft(nodesByBreadth, alpha);
    resolveCollisions(nodesByBreadth, nodeGap, height);
    relaxLeftToRight(nodesByBreadth, alpha);
    resolveCollisions(nodesByBreadth, nodeGap, height);
  }
}
/**
 * Compute the original y-position for each node
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 * @param {Array.<Array.<module:echarts/data/Graph~Node>>} nodesByBreadth
 *     group by the array of all sankey nodes based on the nodes x-position.
 * @param {module:echarts/data/Graph~Edge} edges  edge of sankey view
 * @param {number} height  the whole height of the area to draw the view
 * @param {number} nodeGap  the vertical distance between two nodes
 */


function initializeNodeDepth(nodes, nodesByBreadth, edges, height, nodeGap) {
  var kyArray = [];
  zrUtil.each(nodesByBreadth, function (nodes) {
    var n = nodes.length;
    var sum = 0;
    zrUtil.each(nodes, function (node) {
      sum += node.getLayout().value;
    });
    var ky = (height - (n - 1) * nodeGap) / sum;
    kyArray.push(ky);
  });
  kyArray.sort(function (a, b) {
    return a - b;
  });
  var ky0 = kyArray[0];
  zrUtil.each(nodesByBreadth, function (nodes) {
    zrUtil.each(nodes, function (node, i) {
      node.setLayout({
        y: i
      }, true);
      var nodeDy = node.getLayout().value * ky0;
      node.setLayout({
        dy: nodeDy
      }, true);
    });
  });
  zrUtil.each(edges, function (edge) {
    var edgeDy = +edge.getValue() * ky0;
    edge.setLayout({
      dy: edgeDy
    }, true);
  });
}
/**
 * Resolve the collision of initialized depth (y-position)
 *
 * @param {Array.<Array.<module:echarts/data/Graph~Node>>} nodesByBreadth
 *     group by the array of all sankey nodes based on the nodes x-position.
 * @param {number} nodeGap  the vertical distance between two nodes
 * @param {number} height  the whole height of the area to draw the view
 */


function resolveCollisions(nodesByBreadth, nodeGap, height) {
  zrUtil.each(nodesByBreadth, function (nodes) {
    var node;
    var dy;
    var y0 = 0;
    var n = nodes.length;
    var i;
    nodes.sort(ascendingDepth);

    for (i = 0; i < n; i++) {
      node = nodes[i];
      dy = y0 - node.getLayout().y;

      if (dy > 0) {
        var nodeY = node.getLayout().y + dy;
        node.setLayout({
          y: nodeY
        }, true);
      }

      y0 = node.getLayout().y + node.getLayout().dy + nodeGap;
    } // If the bottommost node goes outside the bounds, push it back up


    dy = y0 - nodeGap - height;

    if (dy > 0) {
      var nodeY = node.getLayout().y - dy;
      node.setLayout({
        y: nodeY
      }, true);
      y0 = node.getLayout().y;

      for (i = n - 2; i >= 0; --i) {
        node = nodes[i];
        dy = node.getLayout().y + node.getLayout().dy + nodeGap - y0;

        if (dy > 0) {
          nodeY = node.getLayout().y - dy;
          node.setLayout({
            y: nodeY
          }, true);
        }

        y0 = node.getLayout().y;
      }
    }
  });
}
/**
 * Change the y-position of the nodes, except most the right side nodes
 *
 * @param {Array.<Array.<module:echarts/data/Graph~Node>>} nodesByBreadth
 *     group by the array of all sankey nodes based on the node x-position.
 * @param {number} alpha  parameter used to adjust the nodes y-position
 */


function relaxRightToLeft(nodesByBreadth, alpha) {
  zrUtil.each(nodesByBreadth.slice().reverse(), function (nodes) {
    zrUtil.each(nodes, function (node) {
      if (node.outEdges.length) {
        var y = sum(node.outEdges, weightedTarget) / sum(node.outEdges, getEdgeValue);
        var nodeY = node.getLayout().y + (y - center(node)) * alpha;
        node.setLayout({
          y: nodeY
        }, true);
      }
    });
  });
}

function weightedTarget(edge) {
  return center(edge.node2) * edge.getValue();
}
/**
 * Change the y-position of the nodes, except most the left side nodes
 *
 * @param {Array.<Array.<module:echarts/data/Graph~Node>>} nodesByBreadth
 *     group by the array of all sankey nodes based on the node x-position.
 * @param {number} alpha  parameter used to adjust the nodes y-position
 */


function relaxLeftToRight(nodesByBreadth, alpha) {
  zrUtil.each(nodesByBreadth, function (nodes) {
    zrUtil.each(nodes, function (node) {
      if (node.inEdges.length) {
        var y = sum(node.inEdges, weightedSource) / sum(node.inEdges, getEdgeValue);
        var nodeY = node.getLayout().y + (y - center(node)) * alpha;
        node.setLayout({
          y: nodeY
        }, true);
      }
    });
  });
}

function weightedSource(edge) {
  return center(edge.node1) * edge.getValue();
}
/**
 * Compute the depth(y-position) of each edge
 *
 * @param {module:echarts/data/Graph~Node} nodes  node of sankey view
 */


function computeEdgeDepths(nodes) {
  zrUtil.each(nodes, function (node) {
    node.outEdges.sort(ascendingTargetDepth);
    node.inEdges.sort(ascendingSourceDepth);
  });
  zrUtil.each(nodes, function (node) {
    var sy = 0;
    var ty = 0;
    zrUtil.each(node.outEdges, function (edge) {
      edge.setLayout({
        sy: sy
      }, true);
      sy += edge.getLayout().dy;
    });
    zrUtil.each(node.inEdges, function (edge) {
      edge.setLayout({
        ty: ty
      }, true);
      ty += edge.getLayout().dy;
    });
  });
}

function ascendingTargetDepth(a, b) {
  return a.node2.getLayout().y - b.node2.getLayout().y;
}

function ascendingSourceDepth(a, b) {
  return a.node1.getLayout().y - b.node1.getLayout().y;
}

function sum(array, f) {
  var sum = 0;
  var len = array.length;
  var i = -1;

  while (++i < len) {
    var value = +f.call(array, array[i], i);

    if (!isNaN(value)) {
      sum += value;
    }
  }

  return sum;
}

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

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

function ascending(a, b) {
  return a - b;
}

function getEdgeValue(edge) {
  return edge.getValue();
}

module.exports = _default;