not use default mutable object

.flake8

@@ -0,0 +1,4 @@
+[flake8]
+max-line-length = 119
+exclude = __init__.py,__pycache__
+ignore = E121,E123,E126,E133,E226,E203,E241,E242,E704,W503,W504,W505,E127,E266,E402,W605,W391,E701,E731

kinpy/chain.py

@@ -16,7 +16,7 @@ def _find_frame_recursive(name: str, frame: frame.Frame) -> Optional[frame.Frame
             if child.name == name:
                 return child
             ret = Chain._find_frame_recursive(name, child)
-            if not ret is None:
+            if ret is not None:
                 return ret
         return None
 
@@ -31,7 +31,7 @@ def _find_link_recursive(name: str, frame: frame.Frame) -> Optional[frame.Frame]
             if child.link.name == name:
                 return child.link
             ret = Chain._find_link_recursive(name, child)
-            if not ret is None:
+            if ret is not None:
                 return ret
         return None
 
@@ -55,13 +55,14 @@ def get_joint_parameter_names(self, exclude_fixed: bool = True) -> List[str]:
 
     def add_frame(self, frame: frame.Frame, parent_name: str) -> None:
         frame = self.find_frame(parent_name)
-        if not frame is None:
+        if frame is not None:
             frame.add_child(frame)
 
     @staticmethod
     def _forward_kinematics(
-        root: frame.Frame, th_dict: Dict[str, float], world: transform.Transform = transform.Transform()
+        root: frame.Frame, th_dict: Dict[str, float], world: Optional[transform.Transform] = None
     ) -> Dict[str, transform.Transform]:
+        world = world or transform.Transform()
         link_transforms = {}
         trans = world * root.get_transform(th_dict.get(root.joint.name, 0.0))
         link_transforms[root.link.name] = trans * root.link.offset
@@ -70,8 +71,9 @@ def _forward_kinematics(
         return link_transforms
 
     def forward_kinematics(
-        self, th: Union[Dict[str, float], List[float]], world=transform.Transform()
+        self, th: Union[Dict[str, float], List[float]], world: Optional[transform.Transform] = None
     ) -> Dict[str, transform.Transform]:
+        world = world or transform.Transform()
         if not isinstance(th, dict):
             jn = self.get_joint_parameter_names()
             assert len(jn) == len(th)
@@ -111,7 +113,7 @@ def _generate_serial_chain_recurse(root_frame: frame.Frame, end_frame_name: str)
                 return [child]
             else:
                 frames = SerialChain._generate_serial_chain_recurse(child, end_frame_name)
-                if not frames is None:
+                if frames is not None:
                     return [child] + frames
         return None
 
@@ -124,8 +126,9 @@ def get_joint_parameter_names(self, exclude_fixed: bool = True) -> List[str]:
         return names
 
     def forward_kinematics(
-        self, th: List[float], world: transform.Transform = transform.Transform(), end_only: bool = True
+        self, th: List[float], world: Optional[transform.Transform] = None, end_only: bool = True
     ) -> Union[transform.Transform, Dict[str, transform.Transform]]:
+        world = world or transform.Transform()
         cnt = 0
         link_transforms = {}
         trans = world

kinpy/frame.py

@@ -10,11 +10,11 @@ class Visual(object):
 
     def __init__(
         self,
-        offset: transform.Transform = transform.Transform(),
+        offset: Optional[transform.Transform] = None,
         geom_type: Optional[str] = None,
         geom_param: Any = None,
     ) -> None:
-        self.offset = offset
+        self.offset = offset or transform.Transform()
         self.geom_type = geom_type
         self.geom_param = geom_param
 
@@ -26,11 +26,11 @@ def __repr__(self) -> None:
 
 class Link(object):
     def __init__(
-        self, name: Optional[str] = None, offset: transform.Transform = transform.Transform(), visuals: List = []
+        self, name: Optional[str] = None, offset: Optional[transform.Transform] = None, visuals: Optional[List] = None
     ) -> None:
         self.name = name
-        self.offset = offset
-        self.visuals = visuals
+        self.offset = offset or transform.Transform()
+        self.visuals = visuals or []
 
     def __repr__(self) -> None:
         return "Link(name='{0}', offset={1}, visuals={2})".format(self.name, self.offset, self.visuals)
@@ -42,17 +42,17 @@ class Joint(object):
     def __init__(
         self,
         name: Optional[str] = None,
-        offset: transform.Transform = transform.Transform(),
+        offset: Optional[transform.Transform] = None,
         joint_type: str = "fixed",
-        axis: List = [0.0, 0.0, 1.0],
+        axis: Optional[List[float]] = None,
     ) -> None:
         self.name = name
-        self.offset = offset
+        self.offset = offset or transform.Transform()
         self.joint_type = joint_type
         if self.joint_type != "fixed" and axis is None:
             self.axis = np.array([0.0, 0.0, 1.0])
         else:
-            self.axis = np.array(axis)
+            self.axis = np.array(axis) if axis is not None else np.array([0.0, 0.0, 1.0])
 
     def __repr__(self) -> None:
         return "Joint(name='{0}', offset={1}, joint_type='{2}', axis={3})".format(
@@ -62,12 +62,16 @@ def __repr__(self) -> None:
 
 class Frame(object):
     def __init__(
-        self, name: Optional[str] = None, link: Link = Link(), joint: Joint = Joint(), children: List["Frame"] = []
+        self,
+        name: Optional[str] = None,
+        link: Optional[Link] = None,
+        joint: Optional[Joint] = None,
+        children: Optional[List["Frame"]] = None,
     ) -> None:
         self.name = "None" if name is None else name
-        self.link = link
-        self.joint = joint
-        self.children = children
+        self.link = link or Link()
+        self.joint = joint or Joint()
+        self.children = children or []
 
     def __str__(self, level: int = 0) -> str:
         ret = " \t" * level + self.name + "\n"

kinpy/jacobian.py

@@ -1,10 +1,11 @@
-from typing import Any, List
+from typing import Any, List, Optional
 import numpy as np
 
 from . import transform
 
 
-def calc_jacobian(serial_chain: Any, th: List[float], tool: transform.Transform = transform.Transform()) -> np.ndarray:
+def calc_jacobian(serial_chain: Any, th: List[float], tool: Optional[transform.Transform] = None) -> np.ndarray:
+    tool = tool or transform.Transform()
     ndof = len(th)
     j_fl = np.zeros((6, ndof))
     cur_transform = tool.matrix()
@@ -32,8 +33,9 @@ def calc_jacobian(serial_chain: Any, th: List[float], tool: transform.Transform
 
 
 def calc_jacobian_frames(
-    serial_chain: Any, th: List[float], link_name: str, tool: transform.Transform = transform.Transform()
+    serial_chain: Any, th: List[float], link_name: str, tool: Optional[transform.Transform] = None
 ) -> np.ndarray:
+    tool = tool or transform.Transform()
     ndof = len(th)
     j_fl = np.zeros((6, ndof))
     cur_transform = tool.matrix()

kinpy/mjcf.py

@@ -1,11 +1,12 @@
-from typing import Dict
+from typing import Dict, Optional
 from . import chain, frame, mjcf_parser, transform
 
 
 JOINT_TYPE_MAP: Dict[str, str] = {"hinge": "revolute", "slide": "prismatic"}
 
 
-def geoms_to_visuals(geom, base=transform.Transform()):
+def geoms_to_visuals(geom, base: Optional[transform.Transform] = None):
+    base = base or transform.Transform()
     visuals = []
     for g in geom:
         if g.type == "capsule":
@@ -20,11 +21,13 @@ def geoms_to_visuals(geom, base=transform.Transform()):
     return visuals
 
 
-def body_to_link(body, base=transform.Transform()):
+def body_to_link(body, base: Optional[transform.Transform] = None):
+    base = base or transform.Transform()
     return frame.Link(body.name, offset=base * transform.Transform(body.quat, body.pos))
 
 
-def joint_to_joint(joint, base=transform.Transform()):
+def joint_to_joint(joint, base: Optional[transform.Transform] = None):
+    base = base or transform.Transform()
     return frame.Joint(
         joint.name,
         offset=base * transform.Transform(pos=joint.pos),
@@ -33,7 +36,8 @@ def joint_to_joint(joint, base=transform.Transform()):
     )
 
 
-def add_composite_joint(root_frame, joints, base=transform.Transform()):
+def add_composite_joint(root_frame, joints, base: Optional[transform.Transform] = None):
+    base = base or transform.Transform()
     if len(joints) > 0:
         root_frame.children = root_frame.children + [
             frame.Frame(link=frame.Link(name=root_frame.link.name + "_child"), joint=joint_to_joint(joints[0], base))

kinpy/transform.py

@@ -1,4 +1,4 @@
-from typing import List, Union
+from typing import List, Optional, Union
 import numpy as np
 import transformations as tf
 
@@ -14,7 +14,11 @@ class Transform(object):
         The translation parameter.
     """
 
-    def __init__(self, rot: Union[List, np.ndarray] = [1.0, 0.0, 0.0, 0.0], pos: np.ndarray = np.zeros(3)) -> None:
+    def __init__(self, rot: Union[List, np.ndarray, None] = None, pos: Optional[np.ndarray] = None) -> None:
+        if rot is None:
+            rot = [1.0, 0.0, 0.0, 0.0]
+        if pos is None:
+            pos = np.zeros(3)
         if rot is None:
             self.rot = np.array([1.0, 0.0, 0.0, 0.0])
         elif len(rot) == 3:

kinpy/visualizer.py

@@ -1,4 +1,4 @@
-from typing import Dict, List, Tuple
+from typing import Dict, List, Optional, Tuple
 import os
 
 import numpy as np
@@ -83,33 +83,38 @@ def load_stl(self, filename: str) -> None:
         reader.SetFileName(filename)
         return reader
 
-    def add_cylinder(self, radius: float, height: float, tf: transform.Transform = transform.Transform()):
+    def add_cylinder(self, radius: float, height: float, tf: Optional[transform.Transform] = None) -> None:
+        tf = tf or transform.Transform()
         cylinder = vtk.vtkCylinderSource()
         cylinder.SetResolution(20)
         cylinder.SetRadius(radius)
         cylinder.SetHeight(height)
         self.add_shape_source(cylinder, tf)
 
-    def add_box(self, size: List[float], tf: transform.Transform = transform.Transform()) -> None:
+    def add_box(self, size: List[float], tf: Optional[transform.Transform] = None) -> None:
+        tf = tf or transform.Transform()
         cube = vtk.vtkCubeSource()
         cube.SetXLength(size[0])
         cube.SetYLength(size[1])
         cube.SetZLength(size[2])
         self.add_shape_source(cube, tf)
 
-    def add_sphere(self, radius: float, tf: transform.Transform = transform.Transform()) -> None:
+    def add_sphere(self, radius: float, tf: Optional[transform.Transform] = None) -> None:
+        tf = tf or transform.Transform()
         sphere = vtk.vtkSphereSource()
         sphere.SetRadius(radius)
         self.add_shape_source(sphere, tf)
 
     def add_capsule(
-        self, radius: float, fromto: np.ndarray, tf: transform.Transform = transform.Transform(), step: float = 0.05
+        self, radius: float, fromto: np.ndarray, tf: Optional[transform.Transform] = None, step: float = 0.05
     ) -> None:
+        tf = tf or transform.Transform()
         for t in np.arange(0.0, 1.0, step):
             trans = transform.Transform(pos=t * fromto[:3] + (1.0 - t) * fromto[3:])
             self.add_sphere(radius, tf * trans)
 
-    def add_mesh(self, filename: str, tf: transform.Transform = transform.Transform()) -> None:
+    def add_mesh(self, filename: str, tf: Optional[transform.Transform] = None) -> None:
+        tf = tf or transform.Transform()
         _, ext = os.path.splitext(filename)
         ext = ext.lower()
         if ext == ".stl":

pyproject.toml

@@ -19,6 +19,8 @@ vtk = "^9.0.1"
 twine = "^3.3.0"
 isort = "^5.9.3"
 black = "^22.6.0"
+flake8 = "^5.0.4"
+flake8-bugbear = "^22.8.23"
 
 [build-system]
 requires = ["poetry-core>=1.0.0", "setuptools"]