update app.py

app.py

@@ -59,20 +59,6 @@ ee.Initialize(project='ee-yashsacisro24')
 # Imagery base selection
 imagery_base = st.selectbox("Select Imagery Base", ["Sentinel", "Landsat", "MODIS", "Custom Input"], index=0)
 
-# Function to fetch date range from GEE
-def fetch_date_range(dataset_id):
-    try:
-        collection = ee.ImageCollection(dataset_id)
-        date_range = collection.reduceColumns(
-            ee.Reducer.minMax(),
-            ["system:time_start"]
-        ).getInfo()
-        start_date = datetime.fromtimestamp(date_range['min'] / 1000).strftime('%Y-%m-%d')
-        end_date = datetime.fromtimestamp(date_range['max'] / 1000).strftime('%Y-%m-%d')
-        return start_date, end_date
-    except Exception as e:
-        return None, None
-
 # Load the appropriate dataset based on imagery base
 if imagery_base == "Sentinel":
     dataset_file = "sentinel_datasets.json"
@@ -96,7 +82,6 @@ elif imagery_base == "Custom Input":
             # Fetch dataset info from GEE
             collection = ee.ImageCollection(custom_dataset_id)
             band_names = collection.first().bandNames().getInfo()
-            start_date, end_date = fetch_date_range(custom_dataset_id)
             data = {
                 f"Custom Dataset: {custom_dataset_id}": {
                     "sub_options": {custom_dataset_id: f"Custom Dataset ({custom_dataset_id})"},
@@ -104,10 +89,6 @@ elif imagery_base == "Custom Input":
                 }
             }
             st.write(f"Fetched bands for {custom_dataset_id}: {', '.join(band_names)}")
-            if start_date and end_date:
-                st.info(f"Valid Date Range: {start_date} to {end_date}")
-            else:
-                st.warning("Could not fetch date range for this dataset.")
         except Exception as e:
             st.error(f"Error fetching dataset: {str(e)}. Please check the dataset ID and ensure it's valid in Google Earth Engine.")
             data = {}
@@ -133,18 +114,36 @@ if main_selection:
     sub_options = data[main_selection]["sub_options"]
     sub_selection = st.selectbox(f"Select Specific {imagery_base} Dataset ID", list(sub_options.keys()))
 
-    # Display the selected dataset ID and fetch date range
+    # Display the selected dataset ID and its availability based on user input
     if sub_selection:
         st.write(f"You selected: {main_selection} -> {sub_options[sub_selection]}")
         st.write(f"Dataset ID: {sub_selection}")
         dataset_id = sub_selection  # Use the key directly as the dataset ID
 
-        # Fetch and display the date range for the selected dataset
-        start_date, end_date = fetch_date_range(dataset_id)
-        if start_date and end_date:
-            st.info(f"Valid Date Range for {dataset_id}: {start_date} to {end_date}")
-        else:
-            st.warning(f"Could not fetch date range for {dataset_id}.")
+        # Fetch and display dataset availability
+        try:
+            # Create an Earth Engine ImageCollection object for the selected dataset
+            collection = ee.ImageCollection(dataset_id)
+            
+            # Get the date range of the collection
+            range_info = collection.reduceColumns(
+                reducer=ee.Reducer.minMax(),
+                selectors=['system:time_start']
+            ).getInfo()
+            
+            # Extract min and max timestamps (in milliseconds) and convert to readable dates
+            min_time = range_info.get('min', None)
+            max_time = range_info.get('max', None)
+            
+            if min_time and max_time:
+                start_date = datetime.fromtimestamp(min_time / 1000).strftime('%Y-%m-%d')
+                end_date = datetime.fromtimestamp(max_time / 1000).strftime('%Y-%m-%d')
+                st.markdown(f"**Dataset Availability:** From {start_date} to {end_date}", unsafe_allow_html=True)
+            else:
+                st.markdown("**Dataset Availability:** Date range not available.", unsafe_allow_html=True)
+                
+        except Exception as e:
+            st.error(f"Error fetching dataset availability: {str(e)}")
 
 # Earth Engine Index Calculator Section
 st.header("Earth Engine Index Calculator")
@@ -178,7 +177,7 @@ if main_selection and sub_selection:
             example = f"'{selected_bands[0]} * {selected_bands[1]} / 2' or '({selected_bands[0]} - {selected_bands[1]}) / ({selected_bands[0]} + {selected_bands[1]})'"
 
         custom_formula = st.text_input(
-            "Enter Custom Formula",
+            "Enter Custom Formula (e.g (B8 - B4) / (B8 + B4) , B4*B3/2)",
             value=default_formula,
             help=f"Use only these bands: {', '.join(selected_bands)}. Examples: {example}"
         )