Add country filter to central viz

src/streamlit_app.py

@@ -117,24 +117,43 @@ st.markdown("""
 Watch how the bubbles (countries) suddenly drop en masse in 2009. This synchronized collapse is the visual signature of a global recession.
 """)
 
-if not df.empty and 'Trade_GDP' in df.columns and 'GDP_Growth' in df.columns:
+# ---COUNTRY FILTER ---
+# Get a list of all unique countries
+all_countries_list = sorted(df['Country Name'].unique().tolist())
+
+# Create the Multiselect Widget
+selected_countries_main = st.multiselect(
+    "🔍 **Filter by Country:** (Leave empty to see the whole world, or select countries to isolate them)",
+    options=all_countries_list,
+    default=[], # Default is empty (show all)
+    placeholder="Choose countries (e.g., United States, China, Germany)..."
+)
+
+# Logic: If countries are selected, filter the dataframe. If not, use the full dataframe.
+if selected_countries_main:
+    df_viz = df[df['Country Name'].isin(selected_countries_main)]
+else:
+    df_viz = df
+
+if not df_viz.empty and 'Trade_GDP' in df_viz.columns and 'GDP_Growth' in df_viz.columns:
     fig_main = px.scatter(
-        df, 
+        df_viz, # Use the filtered dataframe here
         x="Trade_GDP", 
         y="GDP_Growth", 
         animation_frame="Year",
         animation_group="Country Name",
         size="Trade_GDP", 
-        color="GDP_Growth", # Map color to GDP Growth
-        # This scale defines a "Hard Stop" at the middle. 
-        # 0.0 to 0.5 is Red. 0.5 to 1.0 is Blue. No gradient.
+        
+        # STRICT RED/BLUE SCALE
+        color="GDP_Growth", 
         color_continuous_scale=[
             [0, "red"], 
             [0.5, "red"], 
             [0.5, "blue"], 
             [1, "blue"]
         ],
-        color_continuous_midpoint=0, # This ensures the "switch" happens exactly at 0% GDP
+        color_continuous_midpoint=0, 
+        
         hover_name="Country Name",
         range_x=[0, 180], 
         range_y=[-15, 15],
@@ -148,10 +167,10 @@ if not df.empty and 'Trade_GDP' in df.columns and 'GDP_Growth' in df.columns:
     )
 
     # Reference line for Recession
-    fig_main.add_hline(y=0, line_dash="dash", line_color="red", annotation_text="Recession Threshold (0%)")
+    fig_main.add_hline(y=0, line_dash="dash", line_color="black", annotation_text="Recession Threshold (0%)")
 
     st.plotly_chart(fig_main, use_container_width=True)
-    st.caption("Source: World Bank World Development Indicators (WDI). Size of bubble represents trade openness.")
+    st.caption("Source: World Bank World Development Indicators (WDI). Red = Recession, Blue = Growth.")
 else:
     st.warning("Data could not be loaded for the main visualization.")