so it begins...

app.py

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+# -*- coding: utf-8 -*-
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import leafmap.foliumap as leafmap
+import rioxarray
+import geopandas as gpd
+import streamlit as st
+import altair as alt
+import ibis
+from ibis import _
+import ibis.selectors as s
+from streamlit_folium import st_folium
+import json
+
+def extract_geom(gdf, cog):
+    x = (rioxarray.
+         open_rasterio('/vsicurl/'+cog, masked=True).
+         rio.clip(gdf.geometry.values, gdf.crs, from_disk=True)
+    )
+    return x
+
+def read_polygon(polygon):
+    geojson_str = json.dumps(polygon)
+    gdf = gpd.read_file(geojson_str, driver='GeoJSON')
+    gdf.set_crs('epsg:4326')
+    return gdf
+
+def area_hectares(gdf):
+    area = gdf.to_crs("EPSG:9822").area / 10000.
+    return area
+
+
+# +
+st.set_page_config(layout="wide", page_title="Paradise Valley", page_icon="⚡")
+
+st.title("Land Use change in Paradise Valley")
+
+DESCRIPTION='''
+Pan and zoom to the desired location on the map. Then, use the map tools to draw a polygon (pentagon tool), bounding box (square tool) or other shape anywhere on the map.
+(use esc key to exit drawing mode).  Map will display acres of land converted.
+'''
+
+built = "https://huggingface.co/datasets/boettiger-lab/yellowstone/resolve/main/diffs_cog.tif"
+
+
+m = leafmap.Map(center=[35, -100], zoom=3)
+
+## Map controls sidebar
+with st.sidebar:
+    st.markdown(DESCRIPTION)
+
+    cog_layers = {
+            "Expanded Built Land, 2017-2023": built,
+            }
+
+    selection = st.radio("Data", cog_layers)
+    cog = cog_layers[selection]
+    m.add_cog_layer(cog, palette="reds", name=selection,
+                    transparent_bg=True, opacity = 0.8, 
+                    zoom_to_layer=False)
+
+    "### python code for map layer:"
+    "adjust options or add additional layers using leafmap"
+    code = st.text_area(
+        label = "code:",
+        value = code_ex, 
+        height = 400)
+
+# run whatever python code is in the python box, just for fun
+eval(compile(code, "<string>", "exec"))
+st_data = m.to_streamlit(height=400, bidirectional=True)
+
+polygon = st_data["last_active_drawing"]
+# Here we actually compute the total carbon in the requested polygon
+if polygon is not None:
+    gdf = read_polygon(polygon)
+    x = extract_geom(gdf, cog).fillna(0)    
+    count = x.count()
+    area = round(float(area_hectares(gdf)))
+    carbon_total = round(float(x.mean()) * area) # no, mean does not include zeros
+    col2, col3 = st.columns(3)
+    col2.metric(label=f"Area", value=f"{area:,} Hectares")
+    col3.metric(label=f"pixels", value=f"{count:,}")
+
+
+# pixel sums instead of means
+#    value = round(float(x.sum()))
+#    if(selection in ["Vulnerable Carbon (2018)",
+#                     "Manageable Carbon (2018)",
+#                     "Irrecoverable Carbon (2018)"]):
+#        value = value * 9 # 300m pixels, each pixel is 9 hectres
+
+
+st.divider()
+
+'''
+Note: this is just a proof-of-principle demonstration of these tools, and these calculations have not been validated. 
+
+## Credits
+
+### Data sources
+
+- <https://planetarycomputer.microsoft.com/dataset/io-lulc-annual-v02>
+
+### Software stack
+ 
+- Streamlit (python) app hosted on free-tier HuggingFace spaces ([source code](https://huggingface.co/spaces/boettiger-lab/leafmap/blob/main/app.py)).
+- Cloud-optimized geotifs hosted on [Source.Coop](https://source.coop)
+- Mapping with Leafmap, calculations with rasterio
+
+'''

requirements.txt

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+pandas
+pydeck
+pmtiles
+streamlit
+leafmap
+ibis-framework[duckdb]
+altair
+rioxarray
+geopandas
+streamlit-folium