User Guide

Overview

Pathways consumes a datapackage with:

  • Scenario data: model, scenario, year, region, variables, values

  • Mappings: links from scenario variables → LCA activities (and optional subshares)

  • Matrices: prebuilt technosphere/biosphere/characterization elements

The main workflow is driven by pathways.Pathways.

Pathways workflow

  1. Initialize

    from pathways import Pathways
pw = Pathways("remind-SSP2-NPi.zip", ecoinvent_version="3.12")

    The initializer parses the datapackage, builds internal indices, loads classification info and LCIA method names, and prepares the scenario catalog:

    • pw.scenarios: available models, scenarios, regions, years

    • pw.lcia_methods: available impact categories (method names)

    • pw.units: unit conversion helpers

    Example

    print("LCIA methods:", pw.lcia_methods)
# e.g. ["AWARE", "IPCC 2021 climate change GWP 100a", ...]

  2. Calculate

    pw.calculate(
    methods=["AWARE"], models=["REMIND"], scenarios=["SSP2-NPi"],
    regions=["World"], years=[2020, 2050],
    demand_cutoff=1e-3, use_distributions=0
)

    methods must be chosen from the list returned by pw.lcia_methods.

    Output shape

    pw.lca_results is an xarray DataArray with dimensions:

    (act_category, variable, year, region, location, model, scenario, impact_category)

  3. Aggregate for display

    pw.aggregate_results(cutoff=0.01, interpolate=False)

    Aggregates contributions below the cutoff into an "other" category.

  4. Export to Parquet

    path = pw.export_results("my_results")  # → my_results.gzip

Notes

  • Supported ecoinvent_version values are "3.10", "3.11", and "3.12".

  • Matrix files A_matrix.csv and B_matrix.csv are semicolon-delimited and may include a header row.

  • Index files A_matrix_index.csv and B_matrix_index.csv may include a header row.