Geo

Geoprocessing utilities: bounding boxes, coordinate conversions.

import numpy as np

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get_bbox

def get_bbox(
    df:pandas.DataFrame, # DataFrame with coordinate columns
    coord_cols:tuple[str, str]=('LON', 'LAT'), # Column names for (longitude, latitude)
)->shapely.geometry.base.BaseGeometry: # Envelope: a Polygon, or a Point when all coordinates are equal

Bounding box of a DataFrame’s coordinates as a shapely envelope

get_bbox returns the envelope of all the points. Its bounds are (min lon, min lat, max lon, max lat):

df = pd.DataFrame({'LON': np.linspace(-10, 5, 20), 'LAT':  np.linspace(40, 50, 20)})
bbox = get_bbox(df)
test_eq(bbox.bounds, (-10.0, 40.0, 5.0, 50.0))

The envelope is a shapely Polygon:

test_eq(bbox.wkt, 'POLYGON ((-10 40, 5 40, 5 50, -10 50, -10 40))')

When all the points are equal, the envelope is a Point:

bbox = get_bbox(pd.DataFrame({'LON': [0, 0], 'LAT': [1, 1]}))
test_eq(bbox.geom_type, 'Point')
test_eq(bbox.bounds, (0.0, 1.0, 0.0, 1.0))

coord_cols names other coordinate columns:

bbox = get_bbox(pd.DataFrame({'X': [10, 20], 'Y': [30, 40]}), coord_cols=('X', 'Y'))
test_eq(bbox.bounds, (10.0, 30.0, 20.0, 40.0))

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ddmm_to_dd

def ddmm_to_dd(
    ddmmmm:float, # Coord in DDMM.MMMM format (e.g. 45.34 → 45°34')
)->float: # Same coord in decimal degrees

Convert DDMM.MMMM to decimal degrees

ddmm_to_dd converts degrees and decimal minutes, such as 45°34’ written as 45.34, to decimal degrees. A negative coordinate stays negative:

test_close(ddmm_to_dd(45.34), 45.566667)
test_close(ddmm_to_dd(0.0), 0.0)
test_close(ddmm_to_dd(0.30), 0.5)
test_close(ddmm_to_dd(-45.34), -45.566667)
test_close(ddmm_to_dd(180.00), 180.0)