environmentaltools.spatial.create_polygon

environmentaltools.spatial.create_polygon(data, crs='epsg:25830', sides=[])[source]

Create a closed polygon from coordinates and optional additional sides.

Constructs a polygon geometry from a primary set of coordinates, optionally adding additional side segments. Useful for creating polygons from multiple line segments or closing open geometries.

Parameters:

  • data (pd.DataFrame) – Primary polygon coordinates containing columns ‘x’ and ‘y’. These points define the main boundary of the polygon.

  • crs (str, optional) – Coordinate reference system in EPSG format (e.g., ‘epsg:25830’ for ETRS89 UTM Zone 30N, ‘epsg:4326’ for WGS84). Default is ‘epsg:25830’.

  • sides (list of pd.DataFrame or pd.DataFrame, optional) – Additional side segment(s) to append to the polygon boundary. Each DataFrame should contain ‘x’ and ‘y’ coordinate columns. Coordinates are appended in the order provided. Default is empty list.

Returns:

GeoDataFrame containing single polygon geometry with specified CRS. Has one row with the polygon geometry.

Return type:

gpd.GeoDataFrame

Notes

  • Coordinates are concatenated in order: data, then each side in sides list

  • The shapely Polygon constructor automatically closes the polygon

  • Ensure coordinate order forms a valid polygon (no self-intersections)

  • All input DataFrames should use the same coordinate system

Examples

>>> import pandas as pd
>>> import numpy as np
>>> # Define main boundary
>>> data = pd.DataFrame({'x': [0, 10, 10, 0], 'y': [0, 0, 10, 10]})
>>> # Create closed polygon
>>> poly = create_polygon(data, crs='epsg:4326')
>>> print(poly.geometry[0])
POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))

>>> # Add additional side
>>> side = pd.DataFrame({'x': [10, 5], 'y': [10, 15]})
>>> poly = create_polygon(data, crs='epsg:4326', sides=[side])