update app.py

app.py

@@ -371,40 +371,58 @@ def calculate_ndwi(image, geometry, reducer_choice):
     ndwi = image.normalizedDifference(['B3', 'B8']).rename('NDWI')
     return ndwi
 
+# def calculate_custom_formula(image, geometry, custom_formula, reducer_choice, scale=30):
+#     try:
+#         # Check if the custom formula contains a comma (dual-band calculation)
+#         if "," in custom_formula:
+#             # Dual-band calculation (e.g., NDVI, NDWI)
+#             band1 = custom_formula[:custom_formula.find(",")].strip()
+#             band2 = custom_formula[custom_formula.find(",") + 1:].strip()
+            
+#             # Ensure the bands exist in the image
+#             if band1 not in image.bandNames().getInfo() or band2 not in image.bandNames().getInfo():
+#                 st.error(f"One or both bands ({band1}, {band2}) do not exist in the image.")
+#                 return None
+            
+#             # Perform the normalized difference calculation
+#             result = image.normalizedDifference([band1, band2]).rename('custom_formula')
+        
+#         else:
+#             # Single-band calculation 
+#             band = custom_formula.strip()
+            
+#             # Ensure the band exists in the image
+#             if band not in image.bandNames().getInfo():
+#                 st.error(f"The band '{band}' does not exist in the image.")
+#                 return None
+            
+#             # Extract the band
+#             result = image.select(band).rename('custom_formula')
+        
+#         return result
+    
+#     except Exception as e:
+#         st.error(f"Error calculating custom formula: {e}")
+#         return None
+
 def calculate_custom_formula(image, geometry, custom_formula, reducer_choice, scale=30):
     try:
-        # Check if the custom formula contains a comma (dual-band calculation)
         if "," in custom_formula:
-            # Dual-band calculation (e.g., NDVI, NDWI)
-            band1 = custom_formula[:custom_formula.find(",")].strip()
-            band2 = custom_formula[custom_formula.find(",") + 1:].strip()
-            
-            # Ensure the bands exist in the image
-            if band1 not in image.bandNames().getInfo() or band2 not in image.bandNames().getInfo():
-                st.error(f"One or both bands ({band1}, {band2}) do not exist in the image.")
-                return None
-            
-            # Perform the normalized difference calculation
+            band1, band2 = [b.strip() for b in custom_formula.split(",")]
+            band_names = image.bandNames().getInfo()
+            if band1 not in band_names or band2 not in band_names:
+                raise ValueError(f"One or both bands ({band1}, {band2}) do not exist in the image.")
             result = image.normalizedDifference([band1, band2]).rename('custom_formula')
-        
         else:
-            # Single-band calculation 
             band = custom_formula.strip()
-            
-            # Ensure the band exists in the image
-            if band not in image.bandNames().getInfo():
-                st.error(f"The band '{band}' does not exist in the image.")
-                return None
-            
-            # Extract the band
+            band_names = image.bandNames().getInfo()
+            if band not in band_names:
+                raise ValueError(f"The band '{band}' does not exist in the image.")
             result = image.select(band).rename('custom_formula')
-        
         return result
-    
     except Exception as e:
-        st.error(f"Error calculating custom formula: {e}")
-        return None
-    
+        return ee.Image(0).rename('custom_formula').set('error', str(e))
+        
 # Modify aggregation functions to return the correct time period and aggregated results
 def aggregate_data_daily(collection):
     # Extract day from the image date (using the exact date)