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Python tools for quick access to DataBC geo-data available via WFS

Project description

bcdata

Python and command line tools for quick access to DataBC geo-data available via WFS/WCS.

There is a wealth of British Columbia geographic information available as open data, but direct file download urls are not available and the syntax to accesss WFS via ogr2ogr and/or curl/wget can be awkward.

This Python module and CLI attempts to simplify downloads of BC geographic data and smoothly integrate with PostGIS and Python GIS tools like geopandas, fiona and rasterio.

Disclaimer
It is the user's responsibility to check the licensing for any downloads, data are generally licensed as OGL-BC

Installation

pip

$ pip install bcdata

conda

bcdata has several dependencies that may not easily be installed via pip (gdal, fiona, geopandas, rasterio) Installing via miniconda, the conda package manager is recommended on Windows or if you do not wish to install these dependencies yourself. Once conda is installed, download the provided environment.yml file to your system, open the Anaconda Prompt command line from the start menu, navigate to the folder where you saved environment.yml and create/actvate the environment.

conda env create -f environment.yml
conda activate bcdataenv

Configuration

Default PostgreSQL database

The default target database connection (used by bc2pg) can be set via the DATABASE_URL environment variable (the password parameter should not be required if using a .pgpass file)

Linux/Mac: export DATABASE_URL=postgresql://{username}:{password}@{hostname}:{port}/{database}

Windows: SET DATABASE_URL=postgresql://{username}:{password}@{hostname}:{port}/{database}

Layer list cache file

A list of DataBC layers is cached to file to speed request validation. The cache is automatically refreshed if it is more than a day old. The cache file location defaults to ~/.bcdata, but can be configured by setting the a $BCDATA_CACHE environment variable.

export BCDATA_CACHE=/path/to/bcdata_cache

Usage

Typical usage will involve a manual search of the DataBC Catalogue to find a layer of interest. Once a dataset of interest is found, note the key with which to retreive it. This can be either the id/package name (the last portion of the url) or the Object Name (Under Object Description).

For example, for BC Airports, either of these keys will work:

  • id/package name: bc-airports
  • object name: WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW

Note that some packages may have more than one layer - if you request a package like this, bcdata will prompt you with a list of valid object/table names to use instead of the package name.

Python module

import bcdata

# get a feature as geojson
geojson = bcdata.get_data(
    'bc-airports',
    query="AIRPORT_NAME='Terrace (Northwest Regional) Airport'"
)
geojson
{'type': 'FeatureCollection', 'features': [{'type': 'Feature', 'id': 'WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW.fid-f0cdbe4_16811fe142b_-6f34', 'geometry': {'type': 'Point', ...

# optionally, load data as a geopandas GeoDataFrame
gdf = bcdata.get_data(
    'bc-airports',
    query="AIRPORT_NAME='Terrace (Northwest Regional) Airport'",
    as_gdf=True
)
gdf.head()
AERODROME_STATUS AIRCRAFT_ACCESS_IND                          AIRPORT_NAME                ...                TC_LID_CODE WEBSITE_URL                          geometry
0        Certified                   Y  Terrace (Northwest Regional) Airport                ...                       None        None  POINT (-128.5783333 54.46861111)

CLI

Commands available via the bcdata command line interface are documented with the --help option:


$ bcdata --help

Usage: bcdata [OPTIONS] COMMAND [ARGS]...

Options:
  --version  Show the version and exit.
  --help     Show this message and exit.

Commands:
  bc2pg  Download a DataBC WFS layer to postgres
  cat    Write DataBC features to stdout as GeoJSON feature objects.
  dem    Dump BC DEM to TIFF
  dump   Write DataBC features to stdout as GeoJSON feature collection.
  info   Print basic metadata about a DataBC WFS layer as JSON.
  list   List DataBC layers available via WFS

bc2pg

$ bcdata bc2pg --help

Usage: bcdata bc2pg [OPTIONS] DATASET

  Download a DataBC WFS layer to postgres

   $ bcdata bc2pg bc-airports --db_url postgresql://postgres:postgres@localhost:5432/postgis

Options:
  -db, --db_url TEXT      Target database url, defaults to $DATABASE_URL
                          environment variable if set
  --table TEXT            Destination table name
  --schema TEXT           Destination schema name
  --query TEXT            A valid CQL or ECQL query
  -c, --count INTEGER     Total number of features to load
  -p, --pagesize INTEGER  Maximum request size
  -k, --primary_key TEXT  Primary key of dataset
  -s, --schema_only       Dump only the object definitions (schema), not data
  -a, --append            Append to existing table
  -t, --no_timestamp      Do not add download timestamp to bcdata meta table
  -v, --verbose           Increase verbosity.
  -q, --quiet             Decrease verbosity.
  --help                  Show this message and exit.

cat

$ bcdata cat --help

Usage: bcdata cat [OPTIONS] DATASET

  Write DataBC features to stdout as GeoJSON feature objects.

Options:
  --query TEXT                    A valid CQL or ECQL query
  --bounds TEXT                   Bounds: "left bottom right top" or "[left,
                                  bottom, right, top]". Coordinates are BC
                                  Albers (default) or --bounds_crs
  --indent INTEGER                Indentation level for JSON output
  --compact / --not-compact       Use compact separators (',', ':').
  --dst-crs, --dst_crs TEXT       Destination CRS
  -p, --pagesize INTEGER          Maximum request size
  -s, --sortby TEXT               Name of sort field
  --bounds-crs, --bounds_crs TEXT
                                  CRS of provided bounds
  -w, --max_workers INTEGER       Max number of concurrent requests
  -v, --verbose                   Increase verbosity.
  -q, --quiet                     Decrease verbosity.
  --help                          Show this message and exit.

dem

$ bcdata dem --help

Usage: bcdata dem [OPTIONS]

  Dump BC DEM to TIFF

Options:
  -o, --out_file TEXT             Output file
  --bounds TEXT                   Bounds: "left bottom right top" or "[left,
                                  bottom, right, top]". Coordinates are BC
                                  Albers (default) or --bounds_crs  [required]
  --dst-crs, --dst_crs TEXT       Destination CRS
  --bounds-crs, --bounds_crs TEXT
                                  CRS of provided bounds
  -r, --resolution INTEGER
  -a, --align                     Align provided bounds to provincial standard
  -i, --interpolation [nearest|bilinear|bicubic]
  -v, --verbose                   Increase verbosity.
  -q, --quiet                     Decrease verbosity.
  --help                          Show this message and exit.

dump

$ bcdata dump --help

Usage: bcdata dump [OPTIONS] DATASET

  Write DataBC features to stdout as GeoJSON feature collection.

    $ bcdata dump bc-airports
    $ bcdata dump bc-airports --query "AIRPORT_NAME='Victoria Harbour (Shoal Point) Heliport'"
    $ bcdata dump bc-airports --bounds xmin ymin xmax ymax

   It can also be combined to read bounds of a feature dataset using Fiona: ?
   $ bcdata dump bc-airports --bounds $(fio info aoi.shp --bounds)

Options:
  --query TEXT                    A valid CQL or ECQL query
  -o, --out_file TEXT             Output file
  --bounds TEXT                   Bounds: "left bottom right top" or "[left,
                                  bottom, right, top]". Coordinates are BC
                                  Albers (default) or --bounds_crs
  --bounds-crs, --bounds_crs TEXT
                                  CRS of provided bounds
  -v, --verbose                   Increase verbosity.
  -q, --quiet                     Decrease verbosity.
  --help                          Show this message and exit.

info

$ bcdata info --help

Usage: bcdata info [OPTIONS] DATASET

  Print basic metadata about a DataBC WFS layer as JSON.

  Optionally print a single metadata item as a string.

Options:
  --indent INTEGER  Indentation level for JSON output
  --count           Print the count of features.
  --name            Print the table name of the dateset.
  -v, --verbose     Increase verbosity.
  -q, --quiet       Decrease verbosity.
  --help            Show this message and exit.

list

$ bcdata list --help

Usage: bcdata list [OPTIONS]

  List DataBC layers available via WFS

Options:
  -r, --refresh  Refresh the cached list
  --help         Show this message and exit.

CLI notes

Note that bc2pg creates public.bcdata as a meta table tracking the most recent download date for each layer downloaded. Disable with the switch --no_timestamp if you do not wish to create this table or do not have access to public schema.

Example of a record in public.bcdata:

mydb=# select * from bcdata;
                 table_name                  |        date_downloaded
---------------------------------------------+-------------------------------
 whse_imagery_and_base_maps.gsr_airports_svw | 2021-02-17 11:50:34.044481-08

CLI examples

Search the data listing for airports:

  $ bcdata list | grep AIRPORTS
  WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW

Describe a dataset. Note that if we know the id of a dataset, we can use that rather than the object name:

$ bcdata info bc-airports --indent 2
{
  "name": "WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW",
  "count": 455,
  "schema": {
    "properties": {
      "CUSTODIAN_ORG_DESCRIPTION": "string",
      "BUSINESS_CATEGORY_CLASS": "string",
      "BUSINESS_CATEGORY_DESCRIPTION": "string",
      "OCCUPANT_TYPE_DESCRIPTION": "string",
      ...etc...
    },
    "geometry": "GeometryCollection",
    "geometry_column": "SHAPE"
  }
}

The JSON output can be manipulated with jq. For example, to show only the fields available in the dataset:

$ bcdata info bc-airports | jq '.schema.properties'
{
  "CUSTODIAN_ORG_DESCRIPTION": "string",
  "BUSINESS_CATEGORY_CLASS": "string",
  "BUSINESS_CATEGORY_DESCRIPTION": "string",
  "OCCUPANT_TYPE_DESCRIPTION": "string",
  etc...
}

Dump data to geojson (EPSG:4326 only):

$ bcdata dump bc-airports > bc-airports.geojson

Get a single feature and send it to geojsonio (requires geojson-cli). Note the double quotes required around a CQL FILTER provided to the --query option.

$ bcdata dump \
  WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW \
  --query "AIRPORT_NAME='Terrace (Northwest Regional) Airport'" \
   | geojsonio

Save a layer to a geopackage in BC Albers:

$ bcdata cat bc-airports --dst-crs EPSG:3005 \
  | fio collect \
  | fio load -f GPKG --dst-crs EPSG:3005 airports.gpkg

Load data to postgres and run a spatial query:

$ bcdata bc2pg bc-airports \
    --db_url postgresql://postgres:postgres@localhost:5432/postgis

$ bcdata bc2pg WHSE_LEGAL_ADMIN_BOUNDARIES.ABMS_MUNICIPALITIES_SP \
    --db_url postgresql://postgres:postgres@localhost:5432/postgis

$ psql -c \
  "SELECT airport_name
   FROM whse_imagery_and_base_maps.gsr_airports_svw a
   INNER JOIN whse_legal_admin_boundaries.abms_municipalities_sp m
   ON ST_Intersects(a.geom, m.geom)
   WHERE admin_area_name LIKE '%Victoria%'"
                           airport_name
------------------------------------------------------------------
 Victoria Harbour (Camel Point) Heliport
 Victoria Inner Harbour Airport (Victoria Harbour Water Airport)
 Victoria Harbour (Shoal Point) Heliport
(3 rows)

Projections / CRS

CLI

bcdata dump returns GeoJSON in WGS84 (EPSG:4326).

bcdata cat provides the --dst-crs option, use any CRS the WFS server supports.

bcdata bc2pg loads data to PostgreSQL in BC Albers (EPSG:3005).

Python module

bcdata.get_data() defaults to EPSG:4236 but any CRS can be specified (that the server will accept).

Development and testing

bc2pg tests require database postgresql://postgres@localhost:5432/test_bcdata exists and has PostGIS installed:

psql -c "create database test_bcdata"
psql test_bcdata -c "create extension postgis"

Create virtualenv and install bcdata in development mode:

$ mkdir bcdata_env
$ virtualenv bcdata_env
$ source bcdata_env/bin/activate
(bcdata_env)$ git clone git@github.com:smnorris/bcdata.git
(bcdata_env)$ cd bcdata
(bcdata_env)$ pip install -e .[test]
(bcdata_env)$ py.test

Other implementations

  • bcdata R package

  • OWSLib has basic WFS capabilities

  • pgsql-ogr-fdw - read WFS data with postgres foreign data wrapper

  • GDAL / curl / wget:

      # list all layers
      # querying the endpoint this way doesn't seem to work with `VERSION=2.0.0`
      ogrinfo WFS:http://openmaps.gov.bc.ca/geo/ows?VERSION=1.1.0
    
      # define a request url for airports
      airports_url="https://openmaps.gov.bc.ca/geo/pub/WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW/wfs?service=WFS&version=2.0.0&request=GetFeature&typeName=WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW&outputFormat=json&SRSNAME=epsg%3A3005"
    
      # describe airports
      ogrinfo -so $airports_url OGRGeoJSON
    
      # dump airports to geojson
      ogr2ogr \
        -f GeoJSON \
        airports.geojson \
        $airports_url
    
      # load airports to postgres
      ogr2ogr \
        -f PostgreSQL \
        PG:"host=localhost user=postgres dbname=postgis password=postgres" \
        -lco SCHEMA=whse_imagery_and_base_maps \
        -lco GEOMETRY_NAME=geom \
        -nln gsr_airports_svw \
        $airports_url
    
      # Try requesting a larger dataset - ungulate winter range
      uwr_url="https://openmaps.gov.bc.ca/geo/pub/WHSE_WILDLIFE_MANAGEMENT.WCP_UNGULATE_WINTER_RANGE_SP/wfs?service=WFS&version=2.0.0&request=GetFeature&typeName=WHSE_WILDLIFE_MANAGEMENT.WCP_UNGULATE_WINTER_RANGE_SP&outputFormat=json&SRSNAME=epsg%3A3005"
    
      # The request only returns the first 10,000 records
      ogr2ogr \
        uwr.shp \
        -dsco OGR_WFS_PAGING_ALLOWED=ON \
        $uwr_url
    
      # wget works too, but still only 10k records
      wget -O uwr.geojson $uwr_url
    

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