update app.py

app.py

@@ -49,6 +49,10 @@ ee.Initialize(project='ee-yashsacisro24')
 with open("sentinel_datasets.json") as f:
     data = json.load(f)
 
+# Load the band options from band_options.json file
+with open("band_options.json") as f:
+    band_options = json.load(f)
+    
 # Display the title and dataset selection
 st.title("Sentinel Dataset")
 
@@ -68,6 +72,12 @@ index_choice = st.selectbox("Select an Index or Enter Custom Formula", ['NDVI',
 # Initialize custom_formula variable
 custom_formula = ""
 
+# Get the available bands for the selected dataset category and subcategory
+if main_selection and sub_selection:
+    available_bands = band_options.get(main_selection, {}).get(sub_selection, [])
+else:
+    available_bands = []
+
 # Display corresponding formula based on the index selected (case-insensitive)
 if index_choice.lower() == 'ndvi':
     st.write("Formula for NDVI: NDVI = (B8 - B4) / (B8 + B4)")
@@ -76,10 +86,8 @@ elif index_choice.lower() == 'ndwi':
 elif index_choice.lower() == 'average no₂':
     st.write("Formula for Average NO₂: Average NO₂ = Mean(NO2 band)")
 elif index_choice.lower() == 'custom formula':
-    # Get the bands for the selected dataset category
-    bands = data[main_selection]["bands"]
     # Allow the user to select up to 3 bands
-    band_selection = st.multiselect("Select up to 3 bands for custom calculation", bands, max_selections=3)
+    band_selection = st.multiselect("Select up to 3 bands for custom calculation", available_bands, max_selections=3)
     
     # Show the selected bands in the custom formula input
     if len(band_selection) > 0: