Geometries: Points, Lines, and Polygons
Understanding geometric primitives is essential for representing and analyzing spatial features in geospatial data science. The three fundamental geometry types are points, lines, and polygons. Each of these serves a unique purpose when modeling real-world objects.
A point is the simplest geometry, representing a single location in space. You can use points to mark the locations of cities, weather stations, or specific events. For example, a point could represent the geographic center of Paris.
Lines (or more precisely, LineStrings) are sequences of points connected in order, representing linear features. These are ideal for modeling roads, rivers, or railway tracks. For instance, the route of a highway between two cities would be represented as a line.
Polygons are closed shapes defined by a sequence of points where the first and last point are the same. Polygons are used to represent areas such as country borders, lakes, or land parcels. For example, the boundary of a national park would be a polygon.
To work with these geometries in Python, you can use the shapely library, which provides classes for creating and manipulating geometric objects.
1234567891011121314151617181920from shapely.geometry import Point, LineString, Polygon # Create a Point representing a city city = Point(2.3522, 48.8566) # Longitude, Latitude for Paris # Create a LineString representing a road road = LineString([(2.3522, 48.8566), (2.295, 48.8738), (2.1734, 48.8584)]) # Create a Polygon representing a park boundary park = Polygon([ (2.3490, 48.8647), (2.3530, 48.8647), (2.3530, 48.8617), (2.3490, 48.8617), (2.3490, 48.8647) # Close the polygon ]) print("City (Point):", city) print("Road (LineString):", road) print("Park (Polygon):", park)
12345678910111213141516171819202122import pandas as pd from shapely.geometry import Point, LineString, Polygon import geopandas as gpd # List of geometries: a city, a road, and a park geometries = [ Point(2.3522, 48.8566), LineString([(2.3522, 48.8566), (2.295, 48.8738), (2.1734, 48.8584)]), Polygon([ (2.3490, 48.8647), (2.3530, 48.8647), (2.3530, 48.8617), (2.3490, 48.8617), (2.3490, 48.8647) ]) ] # Create a GeoDataFrame gdf = gpd.GeoDataFrame({'geometry': geometries, 'type': ['City', 'Road', 'Park']}) # Display the structure of the GeoDataFrame print(gdf)
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Understanding geometric primitives is essential for representing and analyzing spatial features in geospatial data science. The three fundamental geometry types are points, lines, and polygons. Each of these serves a unique purpose when modeling real-world objects.
A point is the simplest geometry, representing a single location in space. You can use points to mark the locations of cities, weather stations, or specific events. For example, a point could represent the geographic center of Paris.
Lines (or more precisely, LineStrings) are sequences of points connected in order, representing linear features. These are ideal for modeling roads, rivers, or railway tracks. For instance, the route of a highway between two cities would be represented as a line.
Polygons are closed shapes defined by a sequence of points where the first and last point are the same. Polygons are used to represent areas such as country borders, lakes, or land parcels. For example, the boundary of a national park would be a polygon.
To work with these geometries in Python, you can use the shapely library, which provides classes for creating and manipulating geometric objects.
1234567891011121314151617181920from shapely.geometry import Point, LineString, Polygon # Create a Point representing a city city = Point(2.3522, 48.8566) # Longitude, Latitude for Paris # Create a LineString representing a road road = LineString([(2.3522, 48.8566), (2.295, 48.8738), (2.1734, 48.8584)]) # Create a Polygon representing a park boundary park = Polygon([ (2.3490, 48.8647), (2.3530, 48.8647), (2.3530, 48.8617), (2.3490, 48.8617), (2.3490, 48.8647) # Close the polygon ]) print("City (Point):", city) print("Road (LineString):", road) print("Park (Polygon):", park)
12345678910111213141516171819202122import pandas as pd from shapely.geometry import Point, LineString, Polygon import geopandas as gpd # List of geometries: a city, a road, and a park geometries = [ Point(2.3522, 48.8566), LineString([(2.3522, 48.8566), (2.295, 48.8738), (2.1734, 48.8584)]), Polygon([ (2.3490, 48.8647), (2.3530, 48.8647), (2.3530, 48.8617), (2.3490, 48.8617), (2.3490, 48.8647) ]) ] # Create a GeoDataFrame gdf = gpd.GeoDataFrame({'geometry': geometries, 'type': ['City', 'Road', 'Park']}) # Display the structure of the GeoDataFrame print(gdf)
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