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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.

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There is a [wealth of British Columbia geographic information available as open
data](https://catalogue.data.gov.bc.ca/dataset?download_audience=Public),
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 existing Python GIS tools like `fiona` and `rasterio`.


**Note**

- it is the user's responsibility to check the licensing for any downloads, data are generally licensed as [OGL-BC](http://www2.gov.bc.ca/gov/content/governments/about-the-bc-government/databc/open-data/open-government-license-bc)
- this is not specifically endorsed by the Province of Britsh Columbia or DataBC
- use with care, please don't overload the service


## Installation

$ pip install bcdata

To enable autocomplete of dataset names (full object names only) with the command line tools, add this line to your `.bashrc` as per this [guide](https://click.palletsprojects.com/en/7.x/bashcomplete/?highlight=autocomplete#activation).

eval "$(_BCDATA_COMPLETE=source bcdata)"

## Usage

Typical usage will involve a manual search of the [DataBC Catalogue](https://catalogue.data.gov.bc.ca/dataset?download_audience=Public) 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]( https://catalogue.data.gov.bc.ca/dataset/bc-airports), either of these keys will work:

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

### Python module

>>> import bcdata
>>> 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', ...

### CLI

There are several commands available:

$ bcdata --help
Usage: bcdata [OPTIONS] COMMAND [ARGS]...

Options:
--help Show this message and exit.

Commands:
bc2pg Download a DataBC WFS layer to postgres - an ogr2ogr wrapper.
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


#### `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.


#### `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 datasource's name.
--help Show this message and exit.


#### `dump`

$ bcdata dump --help
Usage: bcdata dump [OPTIONS] DATASET

Dump a data layer from DataBC WFS to GeoJSON

$ 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

The values of --bounds must be in BC Albers.

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, quote enclosed (https://docs
.geoserver.org/stable/en/user/tutorials/cql/cql_tutoria
l.html)
-o, --out_file TEXT Output file
--bounds TEXT Bounds: "left bottom right top" or "[left, bottom,
right, top]".
--help Show this message and exit.

#### `cat`

$ bcdata cat --help
Usage: bcdata cat [OPTIONS] DATASET

Download a DataBC WFS layer and write to stdout as GeoJSON feature
objects. In this case, cat does not concatenate.

Options:
--query TEXT A valid `CQL` or `ECQL` query (https://docs.geose
rver.org/stable/en/user/tutorials/cql/cql_tutoria
l.html)
--indent INTEGER Indentation level for JSON output
--bounds TEXT Bounds: "left bottom right top" or "[left,
bottom, right, top]".
--compact / --not-compact Use compact separators (',', ':').
--dst-crs, --dst_crs TEXT Destination CRS.
-p, --pagesize INTEGER Max number of records to request
-s, --sortby TEXT Name of sort field
--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]". [required]
--dst-crs, --dst_crs TEXT Destination CRS.
-r, --resolution INTEGER
--help Show this message and exit.


#### `bc2pg`

$ bcdata bc2pg --help
Usage: bcdata bc2pg [OPTIONS] DATASET

Copy a data from DataBC WFS to postgres - a wrapper around ogr2ogr

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

The default target database can be specified by setting the $DATABASE_URL
environment variable.
https://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls

Options:
-db, --db_url TEXT SQLAlchemy database url
--query TEXT A valid `CQL` or `ECQL` query (https://docs.geoserve
r.org/stable/en/user/tutorials/cql/cql_tutorial.html
)
-p, --pagesize INTEGER Max number of records to request
-s, --sortby TEXT Name of sort field
--help Show this message and exit.

#### 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](https://stedolan.github.io/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](https://tools.ietf.org/html/rfc7946#section-4)):

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

Get a single feature and send it to geojsonio (requires [geojson-cli](https://github.com/mapbox/geojsonio-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 a layer to postgres:

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


## 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

$ 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](https://github.com/bcgov/bcdata)
- [OWSLib](https://github.com/geopython/OWSLib) has basic WFS capabilities
- 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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