From a6c4c89aaa8b2e54fd2f18977e01f662600fa625 Mon Sep 17 00:00:00 2001
From: Jeremie Notebaert <63004366+JeremieNR@users.noreply.github.com>
Date: Tue, 3 Feb 2026 12:09:26 -0500
Subject: [PATCH] Refactor child frame addition to use append method

Use .append() for child/site frames instead of list concatenation to avoid repeated list copies.
---
 src/pytorch_kinematics/mjcf.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/pytorch_kinematics/mjcf.py b/src/pytorch_kinematics/mjcf.py
index 3dc1857..f4610d5 100644
--- a/src/pytorch_kinematics/mjcf.py
+++ b/src/pytorch_kinematics/mjcf.py
@@ -45,7 +45,7 @@ def _build_chain_recurse(m, parent_frame, parent_body):
                 child_joint = frame.Joint(body.name + "_fixed_joint")
             child_link = frame.Link(body.name, offset=tf.Transform3d(rot=body.quat, pos=body.pos))
             child_frame = frame.Frame(name=body.name, link=child_link, joint=child_joint)
-            parent_frame.children = parent_frame.children + [child_frame, ]
+            parent_frame.children.append(child_frame)
             _build_chain_recurse(m, child_frame, body)
 
     # iterate through all sites that are children of parent_body
@@ -54,7 +54,7 @@ def _build_chain_recurse(m, parent_frame, parent_body):
         if site.bodyid == parent_body.id:
             site_link = frame.Link(site.name, offset=tf.Transform3d(rot=site.quat, pos=site.pos))
             site_frame = frame.Frame(name=site.name, link=site_link)
-            parent_frame.children = parent_frame.children + [site_frame, ]
+            parent_frame.children.append(site_frame)
 
 
 def build_chain_from_mjcf(data, body: Union[None, str, int] = None, assets:Optional[Dict[str,bytes]]=None):