Add animated 2d example

examples/heatmap_animated.py

@@ -0,0 +1,104 @@
+"""Animated 2D heatmap example with fixed color normalization across frames."""
+
+from pathlib import Path
+
+import matplotlib.pyplot as plt
+from brainglobe_atlasapi import BrainGlobeAtlas
+from matplotlib.animation import FuncAnimation
+from matplotlib.cm import ScalarMappable
+from matplotlib.colors import Normalize
+
+import brainglobe_heatmap as bgh
+
+# Heat values used throughout the animation.
+values = {
+    "TH": 1,
+    "RSP": 0.2,
+    "AI": 0.4,
+    "SS": -3,
+    "MO": 2.6,
+    "PVZ": -4,
+    "LZ": -3,
+    "VIS": 2,
+    "AUD": 0.3,
+    "RHP": -0.2,
+    "STR": 0.5,
+    "CB": 0.5,
+    "FRP": -1.7,
+    "HIP": 3,
+    "PA": -4,
+}
+
+# Example settings.
+atlas_name = "allen_mouse_25um"
+orientation = "frontal"
+cmap = "Reds"
+step_um = 500
+fps = 3
+
+vmin = min(values.values())
+vmax = max(values.values())
+
+axis_idx = {"frontal": 0, "horizontal": 1, "sagittal": 2}[orientation]
+atlas = BrainGlobeAtlas(atlas_name)
+
+# Build the slice positions for the selected axis.
+max_pos_um = atlas.reference.shape[axis_idx] * atlas.resolution[axis_idx]
+
+positions = list(range(0, int(max_pos_um) + 1, step_um))
+
+# Set up the figure and a shared colorbar.
+fig, ax = plt.subplots(figsize=(10, 4))
+
+# Keep the same color scale across frames.
+norm = Normalize(vmin=vmin, vmax=vmax)
+sm = ScalarMappable(norm=norm, cmap=cmap)
+sm.set_array([])
+fig.colorbar(sm, ax=ax, label="Value")
+
+
+def update_frames(frame_idx):
+    """Draw one animation frame for the current slice position."""
+    ax.clear()
+    pos = positions[frame_idx]
+
+    # Recreate the heatmap for this slice position.
+    heatmap = bgh.Heatmap(
+        values,
+        position=pos,
+        orientation=orientation,
+        cmap=cmap,
+        vmin=vmin,
+        vmax=vmax,
+        format="2D",
+        atlas_name=atlas_name,
+    )
+    heatmap.plot_subplot(fig, ax, show_cbar=False)
+    ax.set_title(f"Position: {pos} um")
+    # Show the current frame number.
+    ax.text(
+        0.02,
+        0.98,
+        f"Frame {frame_idx + 1}/{len(positions)}",
+        transform=ax.transAxes,
+        ha="left",
+        va="top",
+        fontsize=10,
+        bbox={"facecolor": "white", "alpha": 0.7, "edgecolor": "none"},
+    )
+
+
+# Build the animation by calling the update function for each frame.
+ani = FuncAnimation(
+    fig,
+    update_frames,
+    frames=len(positions),
+    interval=500,
+    repeat=False,
+)
+
+# Save the animation next to this example script.
+output_path = Path(__file__).with_name("brain_animation.gif")
+ani.save(output_path, writer="pillow", fps=fps)
+
+plt.show()