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skills/geopandas/references/data-structures.md

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+# GeoPandas Data Structures
+
+## GeoSeries
+
+A GeoSeries is a vector where each entry is a set of shapes corresponding to one observation (similar to a pandas Series but with geometric data).
+
+```python
+import geopandas as gpd
+from shapely.geometry import Point, Polygon
+
+# Create a GeoSeries from geometries
+points = gpd.GeoSeries([Point(1, 1), Point(2, 2), Point(3, 3)])
+
+# Access geometric properties
+points.area
+points.length
+points.bounds
+```
+
+## GeoDataFrame
+
+A GeoDataFrame is a tabular data structure that contains a GeoSeries (similar to a pandas DataFrame but with geographic data).
+
+```python
+# Create from dictionary
+gdf = gpd.GeoDataFrame({
+    'name': ['Point A', 'Point B'],
+    'value': [100, 200],
+    'geometry': [Point(1, 1), Point(2, 2)]
+})
+
+# Create from pandas DataFrame with coordinates
+import pandas as pd
+df = pd.DataFrame({'x': [1, 2, 3], 'y': [1, 2, 3], 'name': ['A', 'B', 'C']})
+gdf = gpd.GeoDataFrame(df, geometry=gpd.points_from_xy(df.x, df.y))
+```
+
+## Key Properties
+
+- **geometry**: The active geometry column (can have multiple geometry columns)
+- **crs**: Coordinate reference system
+- **bounds**: Bounding box of all geometries
+- **total_bounds**: Overall bounding box
+
+## Setting Active Geometry
+
+When a GeoDataFrame has multiple geometry columns:
+
+```python
+# Set active geometry column
+gdf = gdf.set_geometry('other_geom_column')
+
+# Check active geometry column
+gdf.geometry.name
+```
+
+## Indexing and Selection
+
+Use standard pandas indexing with spatial data:
+
+```python
+# Select by label
+gdf.loc[0]
+
+# Boolean indexing
+large_areas = gdf[gdf.area > 100]
+
+# Select columns
+gdf[['name', 'geometry']]
+```