bug: Enable AxesArray in FiniteDifference internals

pysindy/differentiation/finite_difference.py

@@ -1,4 +1,7 @@
+from typing import Union
+
 import numpy as np
+from numpy.typing import NDArray
 
 from .base import BaseDifferentiation
 from pysindy.utils.axes import AxesArray
@@ -218,7 +221,9 @@ def _accumulate(self, coeffs, x):
             np.roll(np.arange(x.ndim), self.axis),
         )
 
-    def _differentiate(self, x, t):
+    def _differentiate(
+        self, x: NDArray, t: Union[NDArray, float, list[float]]
+    ) -> NDArray:
         """
         Apply finite difference method.
         """
@@ -249,6 +254,7 @@ def _differentiate(self, x, t):
                     s[self.axis] = slice(start, stop)
                     interior = interior + x[tuple(s)] * coeffs[i]
         else:
+            t = AxesArray(np.array(t), axes={"ax_time": 0})
             coeffs = self._coefficients(t)
             interior = self._accumulate(coeffs, x)
         s[self.axis] = slice((self.n_stencil - 1) // 2, -(self.n_stencil - 1) // 2)