Dendropy:Addinnernodemidwaybetweentwonodes

1. 导入需要的库和模块。

   import dendropy
   

2. 定义一个函数，将该函数命名为“add_inner_node”。

   def add_inner_node(node1, node2):
   

3. 获取需要添加内部节点的两个节点的距离和相对位置。

   distance = node1.edge_length + node2.edge_length
   relative_position = node1.edge_length / distance
   

4. 创建新的内部节点。

   inner_node = dendropy.Node()
   

5. 将内部节点添加到节点列表中，并设置其父节点。

   node1.parent_node = inner_node
   inner_node.add_child(node1)
   inner_node.add_child(node2)
   node2.parent_node = inner_node
   

6. 更新新节点的长度。

   inner_node.edge_length = distance / 2
   node1.edge_length = inner_node.edge_length * relative_position
   node2.edge_length = inner_node.edge_length * (1 - relative_position)
   

7. 返回内部节点。

   return inner_node
   

完整代码示例：

import dendropy

def add_inner_node(node1, node2):
    distance = node1.edge_length + node2.edge_length
    relative_position = node1.edge_length / distance
    inner_node = dendropy.Node()
    node1.parent_node = inner_node
    inner_node.add_child(node1)
    inner_node.add_child(node2)
    node2.parent_node = inner_node
    inner_node.edge_length = distance / 2
    node1.edge_length = inner_node.edge_length * relative_position
    node2.edge_length = inner_node.edge_length * (1 - relative_position)
    return inner_node

# 示例使用
tree = dendropy.Tree.get_from_string("((A:1,B:2):3,(C:4,D:5):6);", "newick")
node1 = tree.find_node_with_taxon_label("B")
node2 = tree.find_node_with_taxon_label("C")
inner_node = add_inner_node(node1, node2)
print(tree.as_string(schema="new