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Shapefile Format

Description​

Shapefile is a popular geospatial vector data format developed by ESRI. Despite its name, a shapefile actually consists of multiple files (.shp, .shx, .dbf, etc.) that work together. This implementation uses the pyshp library to read and write shapefiles.

File Extensions​

  • .shp - Shapefile main file
  • .shapefile - Shapefile (alias)

Implementation Details​

Reading​

The Shapefile implementation:

  • Reads .shp files using pyshp library
  • Extracts geometry (Point, LineString, Polygon, MultiPoint)
  • Extracts attribute data from associated .dbf file
  • Converts to GeoJSON-like feature format
  • Handles multiple geometry types

Writing​

Writing support:

  • Writes shapefiles with geometry and attributes
  • Automatically determines shape type from first record
  • Creates field definitions based on property types
  • Supports Point, LineString, Polygon, MultiPoint geometries
  • Creates all necessary shapefile components (.shp, .shx, .dbf)

Key Features​

  • Industry standard: Widely used in GIS industry
  • Multiple files: Automatically handles multiple component files
  • Geometry types: Supports Point, LineString, Polygon, MultiPoint
  • Attributes: Full attribute data support
  • Type detection: Automatically detects geometry and attribute types

Usage​

from iterable import open_iterable

# Basic reading
with open_iterable('data.shp') 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.shp', mode='w') as dest:
    feature = {
        'type': 'Feature',
        'geometry': {'type': 'Point', 'coordinates': [102.0, 0.5]},
        'properties': {
            'id': '1',
            'name': 'Location'
        }
    }
    dest.write(feature)

Parameters​

  • encoding (str): File encoding (default: utf8)

Limitations​

  1. pyshp dependency: Requires pyshp package
  2. File path required: Requires filename, not stream
  3. Multiple files: Shapefile consists of multiple files (.shp, .shx, .dbf, etc.)
  4. Geometry types: Limited to Point, LineString, Polygon, MultiPoint
  5. Field types: Field types are determined from first record
  6. Memory usage: All features are loaded into memory during reading

Compression Support​

Shapefiles cannot be directly compressed as they consist of multiple files. However, you can compress the entire directory or use ZIP format for the shapefile components.

Use Cases​

  • GIS workflows: Standard format in GIS applications
  • ESRI compatibility: Working with ESRI ArcGIS data
  • Spatial analysis: Geographic data analysis
  • Data exchange: Common format for exchanging geographic data
  • Cartography: Creating maps and visualizations

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.
  • GeoJSON - JSON-based geographic format
  • KML - Keyhole Markup Language
  • GML - Geography Markup Language
  • GeoPackage - SQLite-based geospatial format