Provide an iterative version on some functions on trees #39519

Oscfon · 2025-02-13T20:14:00Z

This pull request provide iterative methods on AbstractTrees which work both on OrderedTree and BinaryTree.
The problem was that some functions like node_number reach the recursion limit on huge instances.

sage: T = OrderedTree([])
sage: for _ in range(10000):
....:     T = OrderedTree([])
sage: T.node_number()
RecursionError

📝 Checklist

The title is concise and informative.
The description explains in detail what this PR is about.
I have linked a relevant issue or discussion.
I have created tests covering the changes.
I have updated the documentation and checked the documentation preview.

mantepse · 2025-02-14T12:51:47Z

src/sage/combinat/abstract_tree.py

                    if not subtree.is_empty():
                        stack.append(subtree)
            else:
                stack.pop()
                node = stack.pop()
                action(node)

+    def contour_traversal(self,first_action=None, middle_action=None, final_action=None, leaf_action=[]):


Suggested change

def contour_traversal(self,first_action=None, middle_action=None, final_action=None, leaf_action=[]):

def contour_traversal(self, first_action=None, middle_action=None, final_action=None, leaf_action=None):

I don't see why leaf_action should not be None by default.

I want that if you change only first_action and final_action, leaf_action will be the action of both of them but it's perhaps a bad idea.

I don't understand, can you give an example?

If you look at the depth code : i only change the final_action and it change accordingly the leaf_action.
I would like it to work like that.

mantepse · 2025-02-14T13:00:14Z

src/sage/combinat/abstract_tree.py

+        The algorithm is::
+
+            manipulate the root with function `first_action`;
+            iteratively manipulate the root with function `middle_action` 
+                and explore each subtree (by the algorithm) from the
+                leftmost one to the rightmost one;
+            then manipulate the root with function `final_action`;
+            if the root is a leaf it only manipulate with function `leaf_action`.


Suggested change

The algorithm is::

manipulate the root with function `first_action`;

iteratively manipulate the root with function `middle_action`

and explore each subtree (by the algorithm) from the

leftmost one to the rightmost one;

then manipulate the root with function `final_action`;

if the root is a leaf it only manipulate with function `leaf_action`.

ALGORITHM:

- apply `first_action` to the root

- iteratively apply `middle_action` to the root and traverse each subtree from the

leftmost one to the rightmost one

- apply `final_action` to the root if it is not a leaf, and apply `leaf_action` to the root otherwise

(I'm not sure whether my modification introduce mistakes, please double check!)

Suggested change

The algorithm is::

manipulate the root with function `first_action`;

iteratively manipulate the root with function `middle_action`

and explore each subtree (by the algorithm) from the

leftmost one to the rightmost one;

then manipulate the root with function `final_action`;

if the root is a leaf it only manipulate with function `leaf_action`.

ALGORITHM:

- if the root is a leaf, apply `leaf_action`

- else

- apply `first_action` to the root

- iteratively apply `middle_action` to the root and traverse each subtree

from the leftmost one to the rightmost one

- apply `final_action` to the root

It does but i fixed it here.

mantepse · 2025-02-14T13:00:34Z

src/sage/combinat/abstract_tree.py

+            sage: t.contour_traversal(first_action = lambda node: l.append(0),leaf_action = None)
+            sage: len(l)
+            7
+


Suggested change

mantepse · 2025-02-14T13:01:25Z

src/sage/combinat/abstract_tree.py

+        """
+        if first_action is None:
+            def first_action(x):
+                return None


Suggested change

return None

return

mantepse · 2025-02-14T13:01:39Z

src/sage/combinat/abstract_tree.py

+                return None
+        if middle_action is None:
+            def middle_action(x):
+                return None


Suggested change

return None

return

mantepse · 2025-02-14T13:01:50Z

src/sage/combinat/abstract_tree.py

+                return None
+        if final_action is None:
+            def final_action(x):
+                return None


Suggested change

return None

return

mantepse · 2025-02-14T13:02:12Z

src/sage/combinat/abstract_tree.py

+                return None
+        if leaf_action is None:
+            def leaf_action(x):
+                None


Suggested change

None

return

mantepse · 2025-02-14T13:02:30Z

src/sage/combinat/abstract_tree.py

+                final_action(x)
+        stack = []
+        stack.append(self)
+        corners = [0,0]


Suggested change

corners = [0,0]

corners = [0, 0]

mantepse · 2025-02-14T13:03:01Z

src/sage/combinat/abstract_tree.py

+        corners = [0,0]
+        while stack:
+            node = stack.pop()
+            if not(bool(node)):


Suggested change

if not(bool(node)):

if not node:

mantepse · 2025-02-14T13:03:19Z

src/sage/combinat/abstract_tree.py

+                leaf_action(node)
+                corners.pop()
+                corners[-1] += 1
+            elif corners[-1] == 0:


Suggested change

elif corners[-1] == 0:

elif not corners[-1]:

mantepse · 2025-02-14T13:07:19Z

src/sage/combinat/abstract_tree.py

+        def fr_action(node, depths, m, depth):
+            if depths[-1] == depth:
+                m[0] += 1


Suggested change

def fr_action(node, depths, m, depth):

if depths[-1] == depth:

m[0] += 1

m = 0

def fr_action(node):

nonlocal m, depths, depth

if depths[-1] == depth:

m += 1

mantepse · 2025-02-14T13:11:02Z

src/sage/combinat/abstract_tree.py

+        def m_action(node,depths):
+            depths.append(depths[-1]+1)
+        def fn_action(node,depths):
+            depths.pop()


Suggested change

def m_action(node,depths):

depths.append(depths[-1]+1)

def fn_action(node,depths):

depths.pop()

def m_action(node):

nonlocal depths

depths.append(depths[-1] + 1)

def fn_action(node):

nonlocal depths

depths.pop()

mantepse · 2025-02-14T13:11:54Z

src/sage/combinat/abstract_tree.py

+        m = [0]
+        self.contour_traversal(lambda node: fr_action(node, depths,m, depth),lambda node: m_action(node, depths),lambda node: fn_action(node, depths))
+        return m[0]


Suggested change

m = [0]

self.contour_traversal(lambda node: fr_action(node, depths,m, depth),lambda node: m_action(node, depths),lambda node: fn_action(node, depths))

return m[0]

self.contour_traversal(fr_action, m_action, fn_action)

return m

mantepse · 2025-02-14T13:13:14Z

src/sage/combinat/abstract_tree.py

-            return Integer(0 if self.is_empty() else 1)
+        if self.is_empty():
+            return 0
+        def action(node,m):


Suggested change

def action(node,m):

m = []

def action(node):

nonlocal m

mantepse · 2025-02-14T13:13:27Z

src/sage/combinat/abstract_tree.py

+                m.append(0)
+            else:
+                mx = max(m.pop() for _ in node)
+                m.append(mx+1)


Suggested change

m.append(mx+1)

m.append(mx + 1)

mantepse · 2025-02-14T13:14:18Z

src/sage/combinat/abstract_tree.py

+        m = []
+        self.contour_traversal(final_action = lambda node: action(node,m))
+        return m[0]+1


Suggested change

m = []

self.contour_traversal(final_action = lambda node: action(node,m))

return m[0]+1

self.contour_traversal(final_action=action)

return m[0] + 1

Provide an iterative version on some functions on trees

30f50b0

github-actions bot added the s: needs review label Feb 13, 2025

Oscfon added sd125 sage days 125 sd128 tickets of Sage Days 128 Le Teich and removed sd125 sage days 125 labels Feb 13, 2025

Fixed test issues and an error

e8dfafd

mantepse reviewed Feb 14, 2025

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Provide an iterative version on some functions on trees #39519

Provide an iterative version on some functions on trees #39519

Oscfon commented Feb 13, 2025 •

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mantepse Feb 14, 2025

	def contour_traversal(self,first_action=None, middle_action=None, final_action=None, leaf_action=[]):
	def contour_traversal(self, first_action=None, middle_action=None, final_action=None, leaf_action=None):

-        def action(node,m):
+        m = []
+        def action(node):
+            nonlocal m

Provide an iterative version on some functions on trees #39519

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Provide an iterative version on some functions on trees #39519

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Oscfon commented Feb 13, 2025 • edited Loading

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Oscfon commented Feb 13, 2025 •

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