update nyquist_plot lines output to match documentation

Author: murrayrm

control/ctrlplot.py

@@ -41,7 +41,10 @@
 #     # Customize axes (curvilinear grids, shared axes, etc)
 #
 #     # Plot the data
-#     lines = np.full(ax_array.shape, [])
+#     lines = np.empty(ax_array.shape, dtype=object)
+#     for i in range(ax_array.shape[0]):
+#         for j in range(ax_array.shape[1]):
+#             lines[i, j] = []
 #     line_labels = _process_line_labels(label, ntraces, nrows, ncols)
 #     color_offset, color_cycle = _get_color_offset(ax)
 #     for i, j in itertools.product(range(nrows), range(ncols)):

control/descfcn.py

@@ -521,7 +521,8 @@ def describing_function_plot(
     # Plot the Nyquist response
     cplt = dfresp.response.plot(**kwargs)
     ax = cplt.axes[0, 0]        # Get the axes where the plot was made
-    lines[0] = cplt.lines[0]    # Return Nyquist lines for first system
+    lines[0] = np.concatenate(  # Return Nyquist lines for first system
+        cplt.lines.flatten()).tolist()
 
     # Add the describing function curve to the plot
     lines[1] = ax.plot(dfresp.N_vals.real, dfresp.N_vals.imag)

control/freqplot.py

@@ -1886,9 +1886,10 @@ def _parse_linestyle(style_name, allow_false=False):
         kwargs, None, 'upper right')
 
     # Create a list of lines for the output
-    out = np.empty(len(nyquist_responses), dtype=object)
-    for i in range(out.shape[0]):
-        out[i] = []             # unique list in each element
+    out = np.empty((len(nyquist_responses), 4), dtype=object)
+    for i in range(len(nyquist_responses)):
+        for j in range(4):
+            out[i, j] = []      # unique list in each element
 
     for idx, response in enumerate(nyquist_responses):
         resp = response.response
@@ -1938,7 +1939,7 @@ def _parse_linestyle(style_name, allow_false=False):
         p = ax.plot(
             x_reg, y_reg, primary_style[0], color=color, label=label, **kwargs)
         c = p[0].get_color()
-        out[idx] += p
+        out[idx, 0] += p
 
         # Figure out how much to offset the curve: the offset goes from
         # zero at the start of the scaled section to max_curve_offset as
@@ -1950,12 +1951,12 @@ def _parse_linestyle(style_name, allow_false=False):
         x_scl = np.ma.masked_where(scale_mask, resp.real)
         y_scl = np.ma.masked_where(scale_mask, resp.imag)
         if x_scl.count() >= 1 and y_scl.count() >= 1:
-            out[idx] += ax.plot(
+            out[idx, 1] += ax.plot(
                 x_scl * (1 + curve_offset),
                 y_scl * (1 + curve_offset),
                 primary_style[1], color=c, **kwargs)
         else:
-            out[idx] += [None]
+            out[idx, 1] += [None]
 
         # Plot the primary curve (invisible) for setting arrows
         x, y = resp.real.copy(), resp.imag.copy()
@@ -1970,15 +1971,15 @@ def _parse_linestyle(style_name, allow_false=False):
         # Plot the mirror image
         if mirror_style is not False:
             # Plot the regular and scaled segments
-            out[idx] += ax.plot(
+            out[idx, 2] += ax.plot(
                 x_reg, -y_reg, mirror_style[0], color=c, **kwargs)
             if x_scl.count() >= 1 and y_scl.count() >= 1:
-                out[idx] += ax.plot(
+                out[idx, 3] += ax.plot(
                     x_scl * (1 - curve_offset),
                     -y_scl * (1 - curve_offset),
                     mirror_style[1], color=c, **kwargs)
             else:
-                out[idx] += [None]
+                out[idx, 3] += [None]
 
             # Add the arrows (on top of an invisible contour)
             x, y = resp.real.copy(), resp.imag.copy()
@@ -1988,12 +1989,15 @@ def _parse_linestyle(style_name, allow_false=False):
             _add_arrows_to_line2D(
                 ax, p[0], arrow_pos, arrowstyle=arrow_style, dir=-1)
         else:
-            out[idx] += [None, None]
+            out[idx, 2] += [None]
+            out[idx, 3] += [None]
 
         # Mark the start of the curve
         if start_marker:
-            ax.plot(resp[0].real, resp[0].imag, start_marker,
-                     color=c, markersize=start_marker_size)
+            segment = 0 if 0 in rescale_idx else 1      # regular vs scaled
+            out[idx, segment] += ax.plot(
+                resp[0].real, resp[0].imag, start_marker,
+                color=c, markersize=start_marker_size)
 
         # Mark the -1 point
         ax.plot([-1], [0], 'r+')

control/tests/descfcn_test.py

@@ -190,11 +190,11 @@ def test_describing_function_plot():
 
     cplt = response.plot()
     assert len(plt.gcf().get_axes()) == 1       # make sure there is a plot
-    assert len(cplt.lines[0]) == 4 and len(cplt.lines[1]) == 1
+    assert len(cplt.lines[0]) == 5 and len(cplt.lines[1]) == 1
 
     # Call plot directly
     cplt = ct.describing_function_plot(H_larger, F_saturation, amp, omega)
-    assert len(cplt.lines[0]) == 4 and len(cplt.lines[1]) == 1
+    assert len(cplt.lines[0]) == 5 and len(cplt.lines[1]) == 1
 
 
 def test_describing_function_exceptions():

control/tests/nyquist_test.py

@@ -406,15 +406,16 @@ def test_linestyle_checks():
     # Set the line styles
     cplt = ct.nyquist_plot(
         sys, primary_style=[':', ':'], mirror_style=[':', ':'])
-    assert all([line.get_linestyle() == ':' for line in cplt.lines[0]])
+    assert all([lines[0].get_linestyle() == ':' for lines in cplt.lines[0, :]])
 
     # Set the line colors
     cplt = ct.nyquist_plot(sys, color='g')
-    assert all([line.get_color() == 'g' for line in cplt.lines[0]])
+    assert all([line.get_color() == 'g' for line in cplt.lines[0, 0]])
 
     # Turn off the mirror image
     cplt = ct.nyquist_plot(sys, mirror_style=False)
-    assert cplt.lines[0][2:] == [None, None]
+    assert cplt.lines[0, 2] == [None]
+    assert cplt.lines[0, 3] == [None]
 
     with pytest.raises(ValueError, match="invalid 'primary_style'"):
         ct.nyquist_plot(sys, primary_style=False)
@@ -532,22 +533,31 @@ def test_nyquist_rescale():
     sys.name = 'How example'
 
     # Default case
-    cplt = ct.nyquist_plot(sys, indent_direction='left', label='default [0.15]')
+    resp = ct.nyquist_response(sys, indent_direction='left')
+    cplt = resp.plot(label='default [0.15]')
+    assert len(cplt.lines[0, 0]) == 2
+    assert all([len(cplt.lines[0, i]) == 1 for i in range(1, 4)])
 
     # Sharper corner
     cplt = ct.nyquist_plot(
         sys*4, indent_direction='left',
         max_curve_magnitude=17, blend_fraction=0.05, label='fraction=0.05')
+    assert len(cplt.lines[0, 0]) == 2
+    assert all([len(cplt.lines[0, i]) == 1 for i in range(1, 4)])
 
     # More gradual corner
     cplt = ct.nyquist_plot(
         sys*0.25, indent_direction='left',
         max_curve_magnitude=13, blend_fraction=0.25, label='fraction=0.25')
+    assert len(cplt.lines[0, 0]) == 2
+    assert all([len(cplt.lines[0, i]) == 1 for i in range(1, 4)])
 
     # No corner
     cplt = ct.nyquist_plot(
         sys*12, indent_direction='left',
         max_curve_magnitude=19, blend_fraction=0, label='fraction=0')
+    assert len(cplt.lines[0, 0]) == 2
+    assert all([len(cplt.lines[0, i]) == 1 for i in range(1, 4)])
 
     # Bad value
     with pytest.raises(ValueError, match="blend_fraction must be between"):

examples/cds110-L8b_pvtol-complete-limits.ipynb

@@ -830,13 +830,13 @@
     "\n",
     "# Gain margin for Lx\n",
     "neg1overgm_x = -0.67  # vary this manually to find intersection with curve\n",
-    "color = cplt.lines[0][0].get_color()\n",
+    "color = cplt.lines[0, 0][0].get_color()\n",
     "plt.plot(neg1overgm_x, 0, color=color, marker='o', fillstyle='none')\n",
     "gm_x = -1/neg1overgm_x\n",
     "\n",
     "# Gain margin for Ly\n",
     "neg1overgm_y = -0.32  # vary this manually to find intersection with curve\n",
-    "color = cplt.lines[1][0].get_color()\n",
+    "color = cplt.lines[1, 0][0].get_color()\n",
     "plt.plot(neg1overgm_y, 0, color=color, marker='o', fillstyle='none')\n",
     "gm_y = -1/neg1overgm_y\n",
     "\n",
@@ -885,13 +885,13 @@
     "# Phase margin of Lx:\n",
     "th_pm_x = 0.14*np.pi\n",
     "th_plt_x = np.pi + th_pm_x\n",
-    "color = cplt.lines[0][0].get_color()\n",
+    "color = cplt.lines[0, 0][0].get_color()\n",
     "plt.plot(np.cos(th_plt_x), np.sin(th_plt_x), color=color, marker='o')\n",
     "\n",
     "# Phase margin of Ly\n",
     "th_pm_y = 0.19*np.pi\n",
     "th_plt_y = np.pi + th_pm_y\n",
-    "color = cplt.lines[1][0].get_color()\n",
+    "color = cplt.lines[1, 0][0].get_color()\n",
     "plt.plot(np.cos(th_plt_y), np.sin(th_plt_y), color=color, marker='o')\n",
     "\n",
     "print('Margins obtained visually:')\n",
@@ -936,12 +936,12 @@
     "\n",
     "# Stability margin:\n",
     "sm_x = 0.3  # vary this manually to find min which intersects\n",
-    "color = cplt.lines[0][0].get_color()\n",
+    "color = cplt.lines[0, 0][0].get_color()\n",
     "sm_circle = plt.Circle((-1, 0), sm_x, color=color, fill=False, ls=':')\n",
     "cplt.axes[0, 0].add_patch(sm_circle)\n",
     "\n",
     "sm_y = 0.5  # vary this manually to find min which intersects\n",
-    "color = cplt.lines[1][0].get_color()\n",
+    "color = cplt.lines[1, 0][0].get_color()\n",
     "sm_circle = plt.Circle((-1, 0), sm_y, color=color, fill=False, ls=':')\n",
     "cplt.axes[0, 0].add_patch(sm_circle)\n",
     "\n",
@@ -1023,8 +1023,22 @@
   }
  ],
  "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
   "language_info": {
-   "name": "python"
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.13.1"
   }
  },
  "nbformat": 4,