Examples

Basic Usage

>>> from treelib import Node, Tree
>>> tree = Tree()
>>> tree.create_node("Harry", "harry")  # root node
>>> tree.create_node("Jane", "jane", parent="harry")
>>> tree.create_node("Bill", "bill", parent="harry")
>>> tree.create_node("Diane", "diane", parent="jane")
>>> tree.create_node("Mary", "mary", parent="diane")
>>> tree.create_node("Mark", "mark", parent="jane")
>>> tree.show()
Harry
├── Bill
└── Jane
    ├── Diane
    │   └── Mary
    └── Mark

API Examples

Example 1: Expand a tree with specific mode (Tree.DEPTH [default], Tree.WIDTH, Tree.ZIGZAG).

>>> print(','.join([tree[node].tag for node in \
            tree.expand_tree(mode=Tree.DEPTH)]))
Harry,Bill,Jane,Diane,Mary,Mark

Example 2: Expand tree with custom filter.

>>> print(','.join([tree[node].tag for node in \
            tree.expand_tree(filter = lambda x: \
            x.identifier != 'diane')]))
Harry,Bill,Jane,Mark

Example 3: Get a subtree with the root of ‘diane’.

>>> sub_t = tree.subtree('diane')
>>> sub_t.show()
Diane
└── Mary

Example 4: Paste a new tree to the original one.

>>> new_tree = Tree()
>>> new_tree.create_node("n1", 1)  # root node
>>> new_tree.create_node("n2", 2, parent=1)
>>> new_tree.create_node("n3", 3, parent=1)
>>> tree.paste('bill', new_tree)
>>> tree.show()
Harry
├── Bill
│   └── n1
│       ├── n2
│       └── n3
└── Jane
    ├── Diane
    │   └── Mary
    └── Mark

Example 5: Remove the existing node from the tree

>>> tree.remove_node(1)
>>> tree.show()
Harry
├── Bill
└── Jane
    ├── Diane
    │   └── Mary
    └── Mark

Example 6: Move a node to another parent.

>>> tree.move_node('mary', 'harry')
>>> tree.show()
Harry
├── Bill
├── Jane
│   ├── Diane
│   └── Mark
└── Mary

Example 7: Get the height of the tree.

>>> tree.depth()
2

Example 8: Get the level of a node.

>>> node = tree.get_node("bill")
>>> tree.depth(node)
1

Example 9: Print or dump tree structure. For example, the same tree in

basic example can be printed with ‘ascii-em’:

>>> tree.show(line_type="ascii-em")
Harry
╠══ Bill
╠══ Jane
║   ╠══ Diane
║   ╚══ Mark
╚══ Mary

In the JSON form, to_json() takes optional parameter with_data to trigger if the data field is appended into JSON string. For example,

>>> print(tree.to_json(with_data=True))
{"Harry": {"data": null, "children": [{"Bill": {"data": null}}, {"Jane": {"data": null, "children": [{"Diane": {"data": null}}, {"Mark": {"data": null}}]}}, {"Mary": {"data": null}}]}}

Advanced Usage

Sometimes, you need trees to store your own data. The newsest version of treelib supports .data variable to store whatever you want. For example, to define a flower tree with your own data:

>>> class Flower(object): \
        def __init__(self, color): \
            self.color = color

You can create a flower tree now:

>>> ftree = Tree()
>>> ftree.create_node("Root", "root")
>>> ftree.create_node("F1", "f1", parent='root', data=Flower("white"))
>>> ftree.create_node("F2", "f2", parent='root', data=Flower("red"))

Notes: Before version 1.2.5, you may need to inherit and modify the behaviors of tree. Both are supported since then. For flower example,

>>> class FlowerNode(treelib.Node): \
        def __init__(self, color): \
            self.color = color
>>> # create a new node
>>> fnode = FlowerNode("white")