/**
     * Init a graph data structure from data in option series
     */
    getInitialData(option: SankeySeriesOption, ecModel: GlobalModel) {
        const links = option.edges || option.links;
        const nodes = option.data || option.nodes;
        const levels = option.levels;
        this.levelModels = [];
        const levelModels = this.levelModels;

        for (let i = 0; i < levels.length; i++) {
            if (levels[i].depth != null && levels[i].depth >= 0) {
                levelModels[levels[i].depth] = new Model(levels[i], this, ecModel);
            }
            else {
                if (__DEV__) {
                    throw new Error('levels[i].depth is mandatory and should be natural number');
                }
            }
        }
        if (nodes && links) {        // => no return of the data object, when there are links or nodes undefined or null
            const graph = createGraphFromNodeEdge(nodes, links, this, true, beforeLink);
            return graph.data;
        }
        function beforeLink(nodeData: SeriesData, edgeData: SeriesData) {
            nodeData.wrapMethod('getItemModel', function (model: Model, idx: number) {
                const seriesModel = model.parentModel as SankeySeriesModel;
                const layout = seriesModel.getData().getItemLayout(idx);
                if (layout) {
                    const nodeDepth = layout.depth;
                    const levelModel = seriesModel.levelModels[nodeDepth];
                    if (levelModel) {
                        model.parentModel = levelModel;
                    }
                }
                return model;
            });

            edgeData.wrapMethod('getItemModel', function (model: Model, idx: number) {
                const seriesModel = model.parentModel as SankeySeriesModel;
                const edge = seriesModel.getGraph().getEdgeByIndex(idx);
                const layout = edge.node1.getLayout();
                if (layout) {
                    const depth = layout.depth;
                    const levelModel = seriesModel.levelModels[depth];
                    if (levelModel) {
                        model.parentModel = levelModel;
                    }
                }
                return model;
            });
        }
    }