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KML Format

Description​

KML (Keyhole Markup Language) is an XML-based format for representing geographic data. It's widely used by Google Earth and other mapping applications. KML files contain placemarks with geometries (points, lines, polygons) and associated properties.

File Extensions​

  • .kml - KML files

Implementation Details​

Reading​

The KML implementation:

  • Parses KML Placemark elements
  • Extracts geometry (Point, LineString, Polygon)
  • Extracts properties (name, description, ExtendedData)
  • Converts to GeoJSON-like feature format
  • Uses lxml library for XML parsing

Writing​

Writing support:

  • Writes KML Placemark elements
  • Converts GeoJSON-like features to KML
  • Supports Point, LineString, and Polygon geometries
  • Writes properties as ExtendedData
  • Creates proper KML document structure with namespaces

Key Features​

  • Geographic data: Designed for geographic/spatial data visualization
  • Placemark support: Handles KML Placemark elements
  • Multiple geometries: Supports Point, LineString, Polygon
  • Properties: Extracts name, description, and ExtendedData
  • Namespace handling: Proper KML 2.2 namespace support

Usage​

from iterable import open_iterable

# Basic reading
with open_iterable('data.kml') as source:
    for feature in source:
        print(feature)  # Each feature is a dict with geometry and properties
        # feature['type'] == 'Feature'
        # feature['geometry'] contains geometry data
        # feature['properties'] contains attributes

# Writing
with open_iterable('output.kml', mode='w') as dest:
    feature = {
        'type': 'Feature',
        'geometry': {'type': 'Point', 'coordinates': [102.0, 0.5]},
        'properties': {
            'name': 'Location',
            'description': 'A point location'
        }
    }
    dest.write(feature)

Parameters​

  • prefix_strip (bool): Strip XML namespace prefixes (default: True)
  • encoding (str): File encoding (default: utf8)

Limitations​

  1. lxml dependency: Requires lxml package for XML parsing
  2. Memory usage: All features are loaded into memory during reading
  3. Geometry types: Currently supports Point, LineString, Polygon (not MultiGeometry)
  4. ExtendedData: Properties are stored in ExtendedData elements

Compression Support​

KML files can be compressed with all supported codecs:

  • GZip (.kml.gz)
  • BZip2 (.kml.bz2)
  • LZMA (.kml.xz)
  • LZ4 (.kml.lz4)
  • ZIP (.kml.zip)
  • Brotli (.kml.br)
  • ZStandard (.kml.zst)

Use Cases​

  • Google Earth: Creating data for Google Earth visualization
  • Mapping applications: Geographic data for mapping tools
  • Location data: Storing and processing location-based data
  • GIS workflows: Converting between GIS formats

Error Handling​

  • Missing dependency: optional libraries raise ImportError with an install hint (pip install 'iterabledata[<extra>]' when an extra exists).
  • Write mode: read-only formats raise WriteNotSupportedError or ValueError when opened with mode="w".
  • Bad or unsupported input: may raise ValueError, OSError, or library-specific errors.
  • See Troubleshooting for decoding, detection, and engine issues.
  • GML - Geography Markup Language
  • GeoJSON - JSON-based geographic format
  • Shapefile - ESRI Shapefile format
  • XML - Base XML format