Update app.py

app.py

@@ -202,9 +202,69 @@ class PSDAnalyzer:
 
 
      
-        # Add frequency band visualization - Minimalist & Non-Intrusive
+
+        # Add frequency band visualization - Colored bands with legend
         if show_bands:
-            # 1. Vertical dotted lines at band edges (only once per edge)
+            # Use paper coordinates for shapes to avoid affecting data scale
+            # We'll draw rectangles in "paper" space, so they don't distort the plot
+
+            # Get current y-axis range in paper coordinates
+            try:
+                y_min_data = min(trace.y.min() for trace in fig.data if hasattr(trace, 'y'))
+                y_max_data = max(trace.y.max() for trace in fig.data if hasattr(trace, 'y'))
+            except Exception:
+                y_min_data, y_max_data = 1e-5, 1.0
+
+            # Map data y-range to paper y-coordinates (0 to 1)
+            # For log scale, we map log(y) to linear paper space
+            y_log_min = np.log10(y_min_data)
+            y_log_max = np.log10(y_max_data)
+            y_log_range = y_log_max - y_log_min
+
+            # Now loop through bands
+            for band, (low, high) in FREQ_BANDS.items():
+                # Only show if band overlaps visible freq range
+                if high < freq_range[0] or low > freq_range[1]:
+                    continue
+
+                band_low = max(low, freq_range[0])
+                band_high = min(high, freq_range[1])
+
+                # Map y-data to paper coordinates (for log scale)
+                # We want the band to cover full y-axis in paper space
+                # So we set y0=0, y1=1 in paper coordinates
+                # But we must use `yref="paper"` and `xref="x"`
+                fig.add_shape(
+                    type="rect",
+                    x0=band_low,
+                    x1=band_high,
+                    y0=0,
+                    y1=1,
+                    xref="x",
+                    yref="paper",
+                    fillcolor=band_colors[band],
+                    opacity=0.15,
+                    layer="below",
+                    line_width=0,
+                    name=band,
+                )
+
+                # Add label above the plot (outside the plot area)
+                center_x = (band_low + band_high) / 2
+                fig.add_annotation(
+                    x=center_x,
+                    y=1.02,  # Slightly above the top of the plot
+                    text=band,
+                    showarrow=False,
+                    font=dict(size=9, color="dimgray"),
+                    xanchor="center",
+                    yanchor="bottom",
+                    xref="x",
+                    yref="paper",
+                    opacity=0.8,
+                )
+
+            # Optional: Add vertical lines at band edges
             seen_edges = set()
             for low, high in FREQ_BANDS.values():
                 for edge in [low, high]:
@@ -212,7 +272,7 @@ class PSDAnalyzer:
                         fig.add_vline(
                             x=edge,
                             line=dict(color="lightgray", width=1, dash="dot"),
-                            opacity=0.6,
+                            opacity=0.5,
                             layer="below"
                         )
                         seen_edges.add(edge)