FAQ: Trees: Python - Tree Review

This community-built FAQ covers the “Tree Review” exercise from the lesson “Trees: Python”.

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This exercise can be found in the following Codecademy content:

Computer Science

Complex Data Structures

FAQs on the exercise Tree Review

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Hi again I am confused How method traverse work with this line of code nodes_to_visit = [self] do we call self. value or do we call self.children or maybe self like whole TreeNode class with this line I can’t get it, what exactly we assign

class TreeNode:
  def __init__(self, value):
    self.value = value # data
    self.children = [] # references to other nodes

  def add_child(self, child_node):
    # creates parent-child relationship
    print("Adding " + child_node.value)
    self.children.append(child_node) 
    
  def remove_child(self, child_node):
    # removes parent-child relationship
    print("Removing " + child_node.value + " from " + self.value)
    self.children = [child for child in self.children 
                     if child is not child_node]

  def traverse(self):
    # moves through each node referenced from self downwards
    nodes_to_visit = [self]
    while len(nodes_to_visit) > 0:
      current_node = nodes_to_visit.pop()
      print(current_node.value)
      nodes_to_visit += current_node.children
1 Like

Heya, I’m stuck on the exact same thing. Did you figure this out? Thank your for your time)

1 Like

moderators please answer this

Sent me link to exercise and I explain

I Created my own Graph traversal method that looks visually appealing,
An additional step of recursion has been made, run the code to look, how beautiful this traversal looks:

class Tree: def __init__(self,value): self.value = value self.children = [] def add_child(self, child): print(f'Adding child node: {child.value}') self.children.append(child) def remove_child(self, child): self.children = [children for children in self.children if children is not child] def transverse(self, level = 0): counter = level while counter> 0: print(' ', end='') counter -= 1 #Redundent step, clean later main_list = [self] current_main = main_list.pop() print('[-]', current_main.value) # end of redundant step if current_main.children: child_list = current_main.children level += 1 while child_list: current_child = child_list.pop(0) current_child.transverse(level) else: return None mobile = Tree('Mobile Phones') company = Tree('Mobile companies') os = Tree('Mobile OS') nokia = Tree('Nokia') htc = Tree('HTC') oneplus = Tree('OnePlus') redmi = Tree('Redmi') android = Tree('Android') macos = Tree('Mac OS') mobile.add_child(company) mobile.add_child(os) company.add_child(nokia) company.add_child(htc) company.add_child(oneplus) company.add_child(redmi) os.add_child(android) os.add_child(macos) mobile.transverse()