These catalogs are a standardized format for describing metadata and access information
for public datasets, as described here.
Many Socrata and ESRI data portals publish
data.json files in this format describing their catalogs.
Two examples of thes can be found at
This project provides an opinionated way for users to load datasets from these catalogs into the scientific Python ecosystem. At the moment it loads CSVs into Pandas dataframes and GeoJSON files into GeoDataFrames, and ESRI Shapefiles into GeoDataFrames. Future formats could include plain JSON and Parquet.
intake >= 0.4.4 intake_geopandas >= 0.2.2 geopandas >= 0.5.0
intake-dcat is published on PyPI.
You can install it by running the following in your terminal:
pip install intake-dcat
You can test the functionality by opening the example notebooks in the
The package can be imported using
from intake_dcat import DCATCatalog
Loading a catalog
You can load data from a DCAT catalog by providing the URL to the
catalog = DCATCatalog('http://geohub.lacity.org/data.json', name='geohub') len(list(catalog))
You can display the items in the catalog
for entry_id, entry in catalog.items(): display(entry)
If the catalog has too many entries to comfortably print all at once, you can narrow it by searching for a term (e.g. 'district'):
for entry_id, entry in catalog.search('district').items(): display(entry)
Loading a dataset
Once you have identified a dataset, you can load it into a dataframe using
df = entry.read()
This will automatically load that dataset into a Pandas dataframe, or a GeoDataFrame, depending on the source format.
You can read a
DCATCatalog directly in Python using a URL, as done above,
but it is also possible to write a catalog file that itself contains
This allows you to more easily specify DCAT catalogs for use in distribution and version control.
For instance, this YAML file creates entries for two open data catalogs:
metadata: version: 1 sources: # Here we have two data sources for this catalog, which are themselves # DCAT catalogs, one for LA open data, and the other for LA GeoHub la_open_data: # We identify them as being loaded with the DCAT driver driver: dcat # Here we specify the args used to load the catalog args: # The URL to the catalog url: https://data.lacity.org/data.json # An optional name for the catalog. name: la-open-data la_geohub: driver: dcat args: url: http://geohub.lacity.org/data.json name: la_geohub # We can also specify a subset of the datasets in the catalog using an "items" # dictionary. If these are specified, only these datasets will be available in # the resulting catalog. They will be available under the more human-readable # name specified as the key. items: # So, this dataset will be available as "bikeways" bikeways: http://geohub.lacity.org/datasets/2602345a7a8549518e8e3c873368c1d9_0 city_boundary: http://geohub.lacity.org/datasets/09f503229d37414a8e67a7b6ceb9ec43_7 bike_racks: http://geohub.lacity.org/datasets/3b022cced9704108af157d3d5eedb268_2
Command Line Interface
intake-dcat provides a small command line interface for some common operations.
These are invoked using
intake-dcat <subcommand> <options>
This command loads a manifest file that lists a set of DCAT entries, uploads them to a specified s3 bucket, and outputs a new catalog with identical entries pointing to the bucket.
An example manifest is given by
# Name of the LA open data portal la-open-data: # URL to the open data portal catalog url: https://data.lacity.org/data.json # The s3 bucket to upload the data to bucket_uri: s3://my-bucket # A list of data resources to mirror items: lapd_metrics: https://data.lacity.org/api/views/t6kt-2yic # Name of the LA GeoHub data portal la-geohub: # URL to the open data portal catalog url: http://geohub.lacity.org/data.json # The s3 bucket to upload the data to bucket_uri: s3://my-bucket # A list of data resources to mirror items: bikeways: http://geohub.lacity.org/datasets/2602345a7a8549518e8e3c873368c1d9_0 city_boundary: http://geohub.lacity.org/datasets/09f503229d37414a8e67a7b6ceb9ec43_7
This can be mirrored using the command
intake-dcat mirror manifest.yml > new-catalog.yml
This command uses the
boto3 library and assumes it can find AWS credentials.
For more information see this documentation.
This command creates a new intake catalog from a DCAT catalog, and outputs it to standard out. An example command is given by
intake-dcat create data.lacity.org/data.json > catalog.yml