sankeyCenter function

int sankeyCenter(SankeyNode node, int n)

Centers the node based on its incoming/outgoing relationships

• If the node has incoming links (i.e. it is a target), its column is set to its depth.
• Otherwise, if it has outgoing links, its column is set to one less than the minimum depth of its target nodes
• If neither is available, the node is placed in column 0

This function mimics d3‑sankey's "center" alignment

Implementation

int sankeyCenter(SankeyNode node, int n) {
  if (node.targetLinks.isNotEmpty) return node.depth;
  if (node.sourceLinks.isNotEmpty)
    return (node.sourceLinks
            .map((link) => (link.target as SankeyNode).depth)
            .reduce(min)) -
        1;
  return 0;
}