Fix various ruff unknown symbol warnings

roryyorke · roryyorke · commit 71ea2d7df795 · 2025-02-02T07:09:58.000+02:00
diff --git a/control/freqplot.py b/control/freqplot.py
@@ -2219,7 +2219,7 @@ def gangof4_plot(
         See :class:`ControlPlot` for more detailed information.
 
     """
-    if len(args) == 1 and isinstance(arg, FrequencyResponseData):
+    if len(args) == 1 and isinstance(args[0], FrequencyResponseData):
         if any([kw is not None
                 for kw in [omega, omega_limits, omega_num, Hz]]):
             raise ValueError(
diff --git a/control/nichols.py b/control/nichols.py
@@ -136,7 +136,7 @@ def nichols_plot(
 
         # Decide on the system name and label
         sysname = response.sysname if response.sysname is not None \
-            else f"Unknown-{idx_sys}"
+            else f"Unknown-sys_{idx}"
         label_ = sysname if label is None else label[idx]
 
         # Generate the plot
diff --git a/control/optimal.py b/control/optimal.py
@@ -162,7 +162,7 @@ def __init__(
         if trajectory_method is None:
             trajectory_method = 'collocation' if sys.isctime() else 'shooting'
         elif trajectory_method not in _optimal_trajectory_methods:
-            raise NotImplementedError(f"Unkown method {method}")
+            raise NotImplementedError(f"Unknown method {trajectory_method}")
 
         self.shooting = trajectory_method in {'shooting'}
         self.collocation = trajectory_method in {'collocation'}
@@ -1105,7 +1105,7 @@ def solve_ocp(
     # Process (legacy) method keyword
     if kwargs.get('method'):
         method = kwargs.pop('method')
-        if method not in optimal_methods:
+        if method not in _optimal_trajectory_methods:
             if kwargs.get('minimize_method'):
                 raise ValueError("'minimize_method' specified more than once")
             warnings.warn(
diff --git a/control/phaseplot.py b/control/phaseplot.py
@@ -38,6 +38,7 @@
 from . import config
 from .ctrlplot import ControlPlot, _add_arrows_to_line2D, _get_color, \
     _process_ax_keyword, _update_plot_title
+from .exception import ControlArgument
 from .nlsys import NonlinearIOSystem, find_operating_point, \
     input_output_response
 
