Data Commons Client

Overview

Provides comprehensive access to the Data Commons Python API v2 for querying statistical observations, exploring the knowledge graph, and resolving entity identifiers. Data Commons aggregates data from census bureaus, health organizations, environmental agencies, and other authoritative sources into a unified knowledge graph.

Installation

Install the Data Commons Python client with Pandas support:

uv pip install "datacommons-client[Pandas]"

For basic usage without Pandas:

uv pip install datacommons-client

Core Capabilities

The Data Commons API consists of three main endpoints, each detailed in dedicated reference files:

1. Observation Endpoint - Statistical Data Queries

Query time-series statistical data for entities. See references/observation.md for comprehensive documentation.

Primary use cases:

• Retrieve population, economic, health, or environmental statistics

• Access historical time-series data for trend analysis

• Query data for hierarchies (all counties in a state, all countries in a region)

• Compare statistics across multiple entities

• Filter by data source for consistency

Common patterns:

from datacommons_client import DataCommonsClient

client = DataCommonsClient()

Get latest population data

response = client.observation.fetch( variable_dcids=["Count_Person"], entity_dcids=["geoId/06"], # California date="latest" )

Get time series

response = client.observation.fetch( variable_dcids=["UnemploymentRate_Person"], entity_dcids=["country/USA"], date="all" )

Query by hierarchy

response = client.observation.fetch( variable_dcids=["MedianIncome_Household"], entity_expression="geoId/06<-containedInPlace+{typeOf:County}", date="2020" )

2. Node Endpoint - Knowledge Graph Exploration

Explore entity relationships and properties within the knowledge graph. See references/node.md for comprehensive documentation.

Primary use cases:

• Discover available properties for entities

• Navigate geographic hierarchies (parent/child relationships)

• Retrieve entity names and metadata

• Explore connections between entities

• List all entity types in the graph

Common patterns:

Discover properties

labels = client.node.fetch_property_labels( node_dcids=["geoId/06"], out=True )

Navigate hierarchy

children = client.node.fetch_place_children( node_dcids=["country/USA"] )

Get entity names

names = client.node.fetch_entity_names( node_dcids=["geoId/06", "geoId/48"] )

3. Resolve Endpoint - Entity Identification

Translate entity names, coordinates, or external IDs into Data Commons IDs (DCIDs). See references/resolve.md for comprehensive documentation.

Primary use cases:

• Convert place names to DCIDs for queries

• Resolve coordinates to places

• Map Wikidata IDs to Data Commons entities

• Handle ambiguous entity names

Common patterns:

Resolve by name

response = client.resolve.fetch_dcids_by_name( names=["California", "Texas"], entity_type="State" )

Resolve by coordinates

dcid = client.resolve.fetch_dcid_by_coordinates( latitude=37.7749, longitude=-122.4194 )

Resolve Wikidata IDs

response = client.resolve.fetch_dcids_by_wikidata_id( wikidata_ids=["Q30", "Q99"] )

Typical Workflow

Most Data Commons queries follow this pattern:

Resolve entities (if starting with names):

resolve_response = client.resolve.fetch_dcids_by_name( names=["California", "Texas"] ) dcids = [r["candidates"][0]["dcid"] for r in resolve_response.to_dict().values() if r["candidates"]]

Discover available variables (optional):

variables = client.observation.fetch_available_statistical_variables( entity_dcids=dcids )

Query statistical data:

response = client.observation.fetch( variable_dcids=["Count_Person", "UnemploymentRate_Person"], entity_dcids=dcids, date="latest" )

Process results:

As dictionary

data = response.to_dict()

As Pandas DataFrame

df = response.to_observations_as_records()

Finding Statistical Variables

Statistical variables use specific naming patterns in Data Commons:

Common variable patterns:

• Count_Person

• Total population

• Count_Person_Female

• Female population

• UnemploymentRate_Person

• Unemployment rate

• Median_Income_Household

• Median household income

• Count_Death

• Death count

• Median_Age_Person

• Median age

Discovery methods:

Check what variables are available for an entity

available = client.observation.fetch_available_statistical_variables( entity_dcids=["geoId/06"] )

Or explore via the web interface

https://datacommons.org/tools/statvar

Working with Pandas

All observation responses integrate with Pandas:

response = client.observation.fetch( variable_dcids=["Count_Person"], entity_dcids=["geoId/06", "geoId/48"], date="all" )

Convert to DataFrame

df = response.to_observations_as_records()

Columns: date, entity, variable, value

Reshape for analysis

pivot = df.pivot_table( values='value', index='date', columns='entity' )

API Authentication

For datacommons.org (default):

• An API key is required

• Set via environment variable: export DC_API_KEY="your_key"

• Or pass when initializing: client = DataCommonsClient(api_key="your_key")

• Request keys at: https://apikeys.datacommons.org/

For custom Data Commons instances:

• No API key required

• Specify custom endpoint: client = DataCommonsClient(url="https://custom.datacommons.org")

Reference Documentation

Comprehensive documentation for each endpoint is available in the references/ directory:

• references/observation.md : Complete Observation API documentation with all methods, parameters, response formats, and common use cases

• references/node.md : Complete Node API documentation for graph exploration, property queries, and hierarchy navigation

• references/resolve.md : Complete Resolve API documentation for entity identification and DCID resolution

• references/getting_started.md : Quickstart guide with end-to-end examples and common patterns

Additional Resources

• Official Documentation: https://docs.datacommons.org/api/python/v2/

• Statistical Variable Explorer: https://datacommons.org/tools/statvar

• Data Commons Browser: https://datacommons.org/browser/

• GitHub Repository: https://github.com/datacommonsorg/api-python

Tips for Effective Use

• Always start with resolution: Convert names to DCIDs before querying data

• Use relation expressions for hierarchies: Query all children at once instead of individual queries

• Check data availability first: Use fetch_available_statistical_variables() to see what's queryable

• Leverage Pandas integration: Convert responses to DataFrames for analysis

• Cache resolutions: If querying the same entities repeatedly, store name→DCID mappings

• Filter by facet for consistency: Use filter_facet_domains to ensure data from the same source

• Read reference docs: Each endpoint has extensive documentation in the references/ directory