Add zoomed in region to show smoothness of streamlines

eytanadler · eytanadler · commit a2f8a8bb328d · 2024-12-20T21:47:23.000-05:00
diff --git a/galleries/examples/images_contours_and_fields/plot_streamplot.py b/galleries/examples/images_contours_and_fields/plot_streamplot.py
@@ -77,7 +77,7 @@
 axs[7].set_title('Streamplot with unbroken streamlines')
 
 plt.tight_layout()
-plt.show()
+# plt.show()
 
 # %%
 # Streamline computation
@@ -93,7 +93,7 @@
 # This example shows how adjusting the maximum allowed step size and error for
 # the integrator changes the appearance of the streamline. The differences can
 # be subtle, but can be observed particularly where the streamlines have
-# high curvature.
+# high curvature (as shown in the zoomed in region).
 
 # Linear potential flow over a lifting cylinder
 n = 50
@@ -110,37 +110,56 @@
 seed_pts = np.column_stack((np.full(n_seed, -1.75), np.linspace(-2, 2, n_seed)))
 
 _, axs = plt.subplots(3, 1, figsize=(6, 14))
+th_circ = np.linspace(0, 2 * np.pi, 100)
 for ax, max_val in zip(axs, [0.05, 1, 5]):
-    t_start = time.time()
-    ax.streamplot(
-        x,
-        y,
-        vx,
-        vy,
-        start_points=seed_pts,
-        broken_streamlines=False,
-        arrowsize=1e-10,
-        linewidth=0.6,
-        color="k",
-        integration_max_step_scale=max_val,
-        integration_max_error_scale=max_val,
-    )
-
+    ax_ins = ax.inset_axes([0.0, 0.7, 0.3, 0.35])
+    for ax_curr, is_inset in zip([ax, ax_ins], [False, True]):
+        t_start = time.time()
+        ax_curr.streamplot(
+            x,
+            y,
+            vx,
+            vy,
+            start_points=seed_pts,
+            broken_streamlines=False,
+            arrowsize=1e-10,
+            linewidth=2 if is_inset else 0.6,
+            color="k",
+            integration_max_step_scale=max_val,
+            integration_max_error_scale=max_val,
+        )
+        if is_inset:
+            t_total = time.time() - t_start
+
+        # Draw the cylinder
+        ax_curr.fill(
+            np.cos(th_circ),
+            np.sin(th_circ),
+            color="w",
+            ec="k",
+            lw=6 if is_inset else 2,
+        )
+
+        # Set axis properties
+        ax_curr.set_aspect("equal")
+
+    # Label properties of each circle
     text = f"integration_max_step_scale: {max_val}\n" \
         f"integration_max_error_scale: {max_val}\n" \
-        f"streamplot time: {time.time() - t_start:.2f} sec"
+        f"streamplot time: {t_total:.2f} sec"
     if max_val == 1:
         text += "\n(default)"
     ax.text(0.0, 0.0, text, ha="center", va="center")
 
-# Draw the cylinder
-th_circ = np.linspace(0, 2 * np.pi, 100)
-for ax in axs:
-    ax.fill(np.cos(th_circ), np.sin(th_circ), color="w", ec="k")
+    # Set axis limits and show zoomed region
+    ax_ins.set_xlim(-1.2, -0.7)
+    ax_ins.set_ylim(-0.8, -0.4)
+    ax_ins.set_yticks(())
+    ax_ins.set_xticks(())
 
-    ax.set_aspect("equal")
     ax.set_ylim(-1.5, 1.5)
     ax.axis("off")
+    ax.indicate_inset_zoom(ax_ins, ec="k")
 
 plt.tight_layout()
 plt.show()
diff --git a/lib/matplotlib/tests/baseline_images/test_streamplot/streamplot_integration.png b/lib/matplotlib/tests/baseline_images/test_streamplot/streamplot_integration.png
diff --git a/lib/matplotlib/tests/test_streamplot.py b/lib/matplotlib/tests/test_streamplot.py
@@ -117,29 +117,45 @@ def test_integration_options():
     seed_pts = np.column_stack((np.full(n_seed, -1.75), np.linspace(-2, 2, n_seed)))
 
     fig, axs = plt.subplots(3, 1, figsize=(6, 14))
-    for ax, max_val in zip(axs, [0.05, 1, 5]):
-        ax.streamplot(
-            x,
-            y,
-            vx,
-            vy,
-            start_points=seed_pts,
-            broken_streamlines=False,
-            arrowsize=1e-10,
-            linewidth=0.6,
-            color="k",
-            integration_max_step_scale=max_val,
-            integration_max_error_scale=max_val,
-        )
-
-    # Draw the cylinder
     th_circ = np.linspace(0, 2 * np.pi, 100)
-    for ax in axs:
-        ax.fill(np.cos(th_circ), np.sin(th_circ), color="w", ec="k")
+    for ax, max_val in zip(axs, [0.05, 1, 5]):
+        ax_ins = ax.inset_axes([0.0, 0.7, 0.3, 0.35])
+        for ax_curr, is_inset in zip([ax, ax_ins], [False, True]):
+            ax_curr.streamplot(
+                x,
+                y,
+                vx,
+                vy,
+                start_points=seed_pts,
+                broken_streamlines=False,
+                arrowsize=1e-10,
+                linewidth=2 if is_inset else 0.6,
+                color="k",
+                integration_max_step_scale=max_val,
+                integration_max_error_scale=max_val,
+            )
+
+            # Draw the cylinder
+            ax_curr.fill(
+                np.cos(th_circ),
+                np.sin(th_circ),
+                color="w",
+                ec="k",
+                lw=6 if is_inset else 2,
+            )
+
+            # Set axis properties
+            ax_curr.set_aspect("equal")
+
+        # Set axis limits and show zoomed region
+        ax_ins.set_xlim(-1.2, -0.7)
+        ax_ins.set_ylim(-0.8, -0.4)
+        ax_ins.set_yticks(())
+        ax_ins.set_xticks(())
 
-        ax.set_aspect("equal")
         ax.set_ylim(-1.5, 1.5)
         ax.axis("off")
+        ax.indicate_inset_zoom(ax_ins, ec="k")
 
     fig.tight_layout()
 
