GeoParquet-Pydantic

A lightweight, pydantic centric library for validating GeoParquet files (or PyArrow Tables) and converting between GeoJSON and GeoParquet...without GDAL!

Motivation: This project started at the 2024 San Fransisco GeoParquet Community hackathon, and arose out of a simple observation: why must Python users install the massive GDAL dependency (typically via GeoPandas) to do simple GeoJSON<>GeoParquet conversions.

Is this library the right choice for you?:

• Do you need to use a wide variety of Geospatial functions? If so, you will likely have to add GDAL/GeoPandas as a dependency anyways, making this ibrary's conversion functions probably redundant.
• Is your workflow command line centric? If so you may want to consider Planet Lab's simular CLI tool gpq, which is written in Go and substantially faster.
• Otherwise, if you are using Python and want to avoid unnecessary bulky dependencies, this library will be a great choice!

Note: All user-exposed functions and schema classes are available at the top level (i.e., geoparquet_pydantic.validate_geoparquet_table(...)) of this library.

Features

pydantic Schemas

• GeometryColumnMetadata: A pydantic model that validates a geometry column's (aka primary_column) metadata. This is nested within the following schema.
• GeoParquetMetadata: A pydantic model for the metadata assigned to the "geo" key in a pyarrow.Table that allows it to be read by GeoParquet readers once saved.

For an explanation of these schemas, please refence the geoparquet repository.

Validation functions

Convenience functions that simply uses GeoParquetMetadata to return a bool depending on whether the GeoParquet metadata obeys the schema.

Validate a pyarrow.Table's GeoParquet metadata:

def validate_geoparquet_table(
    table: pyarrow.Table,
    primary_column: Optional[str] = None,
) -> bool:
  """Validates a the GeoParquet metadata of a pyarrow.Table.

    Args:
        table (pyarrow.Table): The table to validate.
        primary_column (Optional[str], optional): The name of the primary geometry column.
            Defaults to None.

    Returns:
        bool: True if the metadata is valid, False otherwise.
    """
    ...

Validate a Parquet file's GeoParquet metadata:

def validate_geoparquet_file(
    geoparquet_file: str | Path | pyarrow.parquet.ParquetFile,
    primary_column: Optional[str] = None,
    read_file_kwargs: Optional[dict] = None,
) -> bool:
    """Validates that a parquet file has correct GeoParquet metadata without opening it.

    Args:
        geoparquet_file (str | Path | ParquetFile): The file to validate.
        primary_column (str, optional): The primary column name. Defaults to 'geometry'.
        read_file_kwargs (dict, optional): Kwargs to be passed into pyarrow.parquet.ParquetFile().
            See: https://arrow.apache.org/docs/python/generated/pyarrow.parquet.ParquetFile.html#pyarrow-parquet-parquetfile

    Returns:
        bool: True if the metadata is valid, False otherwise.
    """
    ...

Conversion functions

Convert from geojson_pydantic.FeatureCollection to a GeoParquet pyarrow.Table

def geojson_to_geoparquet(
    geojson: FeatureCollection | Path,
    primary_column: Optional[str] = None,
    column_schema: Optional[pyarrow.Schema] = None,
    add_none_values: Optional[bool] = False,
    geo_metadata: GeoParquetMetadata | dict | None = None,
    **kwargs,
) -> pyarrow.Table:
    """Converts a GeoJSON Pydantic FeatureCollection to an Arrow table with geoparquet
    metadata.

    To save to a file, simply use pyarrow.parquet.write_table() on the returned table.

    Args:
        geojson (FeatureCollection): The GeoJSON Pydantic FeatureCollection.
        primary_column (str, optional): The name of the primary column. Defaults to None.
        column_schema (pyarrow.Schema, optional): The Arrow schema for the table. Defaults to None.
        add_none_values (bool, default=False): Whether to fill missing column values
            specified in param:column_schema with 'None' (converts to pyarrow.null()).
        geo_metadata (GeoParquet | dict | None, optional): The GeoParquet metadata.
        **kwargs: Additional keyword arguments for the Arrow table writer.

    Returns:
        The Arrow table with GeoParquet metadata.
    """
    ...

Convert from a GeoParquet pyarrow.Table or file to a geojson_pydantic.FeatureCollection

def geoparquet_to_geojson(
    geoparquet: pyarrow.Table | str | Path,
    primary_column: Optional[str] = None,
    max_chunksize: Optional[int] = None,
    max_workers: Optional[int] = None,
) -> FeatureCollection:
    """Converts an Arrow table with GeoParquet metadata to a GeoJSON Pydantic
    FeatureCollection.

    Args:
        geoparquet (pyarrow.Table): Either an Arrow.Table or parquet with GeoParquet metadata.
        primary_column (str, optional): The name of the primary column. Defaults to 'geometry'.
        max_chunksize (int, optional): The maximum chunksize to read from the parquet file. Defaults to 1000.
        max_workers (int, optional): The maximum number of workers to use for parallel processing.
            Defaults to 0 (runs sequentially). Use -1 for all available cores.

    Returns:
        FeatureCollection: The GeoJSON Pydantic FeatureCollection.
    """
    ...

Getting Started

Install from PyPi:

pip install geoparquet-pydantic

Or from source:

$ git clone https://github.com/xaviernogueira/geoparquet-pydantic.git
$ cd geoparquet-pydantic
$ pip install .

Then import with an underscore:

import geoparquet_pydantic

Or just import the functions/classes you need from the top-level:

from geoparquet_pydantic import (
  GeometryColumnMetadata,
  GeoParquetMetadata,
  validate_geoparquet_table,
  validate_geoparquet_file,
  geojson_to_geoparquet,
  geoparquet_to_geojson,
)

Roadmap

• [ ] Make CLI file<>file functions w/ click.
• [ ] Add parrallelized Parquet read for geoparquet_pydantic.geoparquet_to_geojson().

Contribute

We encourage contributions, feature requests, and bug reports!

Here is our recomended workflow:

• Use dev-requirements.txt to install our development dependencies.
• Make your edits using pyright as a linter.
• Use pre-commit run --all-file before commiting your work.
• If you add a new feature, we request that you add test coverage for it.

Happy coding!