NGD Wrappers python

This is a python package which extends and enhances the flexibility and functionality of Ordnance Survey NGD API - Features.

Features

1. Wrapping core OS NGD API - Features functionality
   • Calls to the Features and Collections endpoints can be made through python functions.
2. Limit Extension
   • The default upper limit for the number of features returned can be extended above the default of 100 through automatic pagination.
3. Geometry Extension
   • Multi-geometry search areas can be provided as spatial filters, including Geometry Collections.
   • Each search area is searched in turn.
   • The base NGD API is low-performing when multigeometries are searched and the component geometries are a long way apart. The wrapper resolves this issue.
4. Collection Extension
   • Multiple collections can be searched at once.
   • This is useful when data relevant to a use-case spans multiple collections.
5. Latest Collections
   • Retrieve a simple list of the latest schema versions available for each NGD collection, for for a specified set.
   • The latest schema version for a given collection can be automatically used for a features request.
6. CRS Specification
   • Short/simple versions of CRS codes can be used (eg. 27700, 4326, CRS84) instead of the full URIs.
   • This applies for all crs parameters:
     • crs
     • bbox-crs
     • filter-crs
7. Filter Parameters
   • Rather than writing full CQL filters, filter parameters for equality (=) can be supplied as a dictionary.
   • Rather than writing a full CQL spatial filter, WKT geometries can be supplied as a separate parameter.
8. Automatic Oauth2 authentication
   • When CLIENT_ID (project api key) and CLIENT_SECRET (project api secret) are provided as environment variables, authentication is processed automatically via 5-minute access tokens.
   • Once these environment variables are supplied, the user does not need to do any further action to authenticate their requests.

Install

The library can be installed using pip. It is not currently published to a repository such as PyPI but it can be installed by direct link to the latest version tag on GitHub.

$ pip install git+https://github.com/Geovation/catalyst-ngd-wrappers-python@0.1.0

Replace the version tag with the latest version. To upgrade, reinstall with the latest tag (or whichever tag you choose).

Usage

import catalyst_ngd_wrappers

collection = ['bld-fts-building', 'trn-ntwk-road', 'wtr-fts-water']
wkt = 'GEOMETRYCOLLECTION (POLYGON ((400000 400000, 400090 400050, 400050 400000, 400000 40050, 400000 400000)), LINESTRING(399990 399990, 399000 399000))'
universal_crs = 27700
limit = 300

os.environ['CLIENT_ID'] = '<YOUR_PROJECT_API_KEY>'
os.environ['CLIENT_SECRET'] = '<YOUR_PROJECT_API_SECRET>'

# Returns a hierarchical set of geojsons containing OS data for for latest versions of selected collections, for the set of search areas provided'
data = items_limit_geom_col(
    collection = collection,
    wkt = wkt,
    use_latest_collection = True,
    hierarchical_output = True
    query_params = {
        'wkt': universal_crs,
        'filter-crs': universal_crs,
        'limit': limit,
    }
)