From f737ae13d4236e439effb96daf1bdc677f3d6215 Mon Sep 17 00:00:00 2001
From: Jake <37048747+Jacob-Stevens-Haas@users.noreply.github.com>
Date: Wed, 3 Jan 2024 17:07:13 +0000
Subject: [PATCH] BUG: Set mutable default function_library in __init__() body

---
 pysindy/feature_library/pde_library.py      | 8 ++++----
 pysindy/feature_library/weak_pde_library.py | 7 ++++---
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/pysindy/feature_library/pde_library.py b/pysindy/feature_library/pde_library.py
index 89b53a35c..44ce3a5c6 100644
--- a/pysindy/feature_library/pde_library.py
+++ b/pysindy/feature_library/pde_library.py
@@ -1,5 +1,6 @@
 import warnings
 from itertools import product as iproduct
+from typing import Optional
 
 import numpy as np
 from sklearn.utils.validation import check_is_fitted
@@ -85,9 +86,7 @@ class PDELibrary(BaseFeatureLibrary):
 
     def __init__(
         self,
-        function_library: BaseFeatureLibrary = PolynomialLibrary(
-            degree=3, include_bias=False
-        ),
+        function_library: Optional[BaseFeatureLibrary] = None,
         derivative_order=0,
         spatial_grid=None,
         temporal_grid=None,
@@ -110,7 +109,8 @@ def __init__(
         self.num_trajectories = 1
         self.differentiation_method = differentiation_method
         self.diff_kwargs = diff_kwargs
-
+        if function_library is None:
+            self.function_library = PolynomialLibrary(degree=3, include_bias=False)
         if derivative_order < 0:
             raise ValueError("The derivative order must be >0")
 
diff --git a/pysindy/feature_library/weak_pde_library.py b/pysindy/feature_library/weak_pde_library.py
index fe82518ff..16e2792a0 100644
--- a/pysindy/feature_library/weak_pde_library.py
+++ b/pysindy/feature_library/weak_pde_library.py
@@ -1,5 +1,6 @@
 import warnings
 from itertools import product as iproduct
+from typing import Optional
 
 import numpy as np
 from scipy.special import binom
@@ -135,9 +136,7 @@ class WeakPDELibrary(BaseFeatureLibrary):
 
     def __init__(
         self,
-        function_library: BaseFeatureLibrary = PolynomialLibrary(
-            degree=3, include_bias=False
-        ),
+        function_library: Optional[BaseFeatureLibrary] = None,
         derivative_order=0,
         spatiotemporal_grid=None,
         interaction_only=True,
@@ -166,6 +165,8 @@ def __init__(
         self.num_trajectories = 1
         self.differentiation_method = differentiation_method
         self.diff_kwargs = diff_kwargs
+        if function_library is None:
+            self.function_library = PolynomialLibrary(degree=3, include_bias=False)
 
         if spatiotemporal_grid is None:
             raise ValueError(