rtreedata.tree

Difficulty in Obtaining Final Leaves from data.tree Package in R

I am currently working with the data.tree package in R to create hierarchical trees. However, I am facing challenges in obtaining the final leaves (terminal nodes) from the tree. Despite following the package documentation, I am unable to retrieve the desired results.

As an example, consider the following tree structure:

# Install the data.tree package if not already installed
# install.packages("data.tree")

# Load the package
library(data.tree)

# Create a root node
root <- Node$new("Root")

# Add the first child
first_child <- root$AddChild("First Child")

# Add the second child
second_child <- root$AddChild("Second Child")

# Add two children to the second child
grandchild1 <- second_child$AddChild("Grandchild 1")
grandchild2 <- second_child$AddChild("Grandchild 2")

# Add a child to Grandchild 1
great_grandchild <- grandchild1$AddChild("Great Grandchild")

# Display the tree
print(root)

Despite my efforts, I cannot find a straightforward way to extract the final leaves: “First Child,” “Great Grandchild,” and “Grandchild 2.”

Could someone please provide guidance on how to correctly obtain the terminal nodes from the data.tree package? Is there a specific function or approach I should be using?

Additionally, I find the package documentation to be complex, and it surprises me that even AI chatbots like Copilot and Gemini struggle with such a seemingly simple task.

Solution

  • There seem to be relevant examples in the node methods senction of the documentation. For example you can get what you want with

    root$Get("name", filterFun=isLeaf)
#        First Child   Great Grandchild       Grandchild 2 
#      "First Child" "Great Grandchild"     "Grandchild 2"

    This returns a named list. You could either unname() it or just take the names() to get a simple vector.

    If you wanted the nodes themselves you could do

    root$Get(identity, filterFun=isLeaf)