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3.0.0 - 2025-10-13

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Summary: This release introduces new model dimensions (periods and scenarios) for multi-period investments and stochastic modeling, along with a redesigned effect sharing system and enhanced I/O capabilities. For detailed migration instructions, see the Migration Guide.

✨ Added

New model dimensions:

  • Period dimension: Enables multi-period investment modeling with distinct decisions in each period for transformation pathway optimization
  • Scenario dimension: Supports stochastic modeling with weighted scenarios for robust decision-making under uncertainty (demand, prices, weather)
    • Control variable independence across scenarios via scenario_independent_sizes and scenario_independent_flow_rates parameters
    • By default, investment sizes are shared across scenarios while flow rates vary per scenario

Redesigned effect sharing system:

Effects now use intuitive share_from_* syntax that clearly shows contribution sources:

costs = fx.Effect('costs', '€', 'Total costs',
    share_from_temporal={'CO2': 0.2},      # From temporal effects
    share_from_periodic={'land': 100})     # From periodic effects

This replaces specific_share_to_other_effects_* parameters and inverts the direction for clearer relationships.

Enhanced I/O and data handling:

  • NetCDF/JSON serialization for all Interface objects and FlowSystem with round-trip support
  • FlowSystem manipulation: sel(), isel(), resample(), copy(), __eq__() methods
  • Direct access to FlowSystem from results without manual restoring (lazily loaded)
  • New FlowResults class and precomputed DataArrays for sizes/flow_rates/flow_hours
  • effects_per_component dataset for component impact evaluation, including all indirect effects through effect shares

Other additions:

  • Balanced storage - charging and discharging sizes can be forced equal via balanced parameter
  • New Storage parameters: relative_minimum_final_charge_state and relative_maximum_final_charge_state for final state control
  • Improved filter methods in results
  • Example for 2-stage investment decisions leveraging FlowSystem resampling

💥 Breaking Changes

  • relative_minimum_charge_state and relative_maximum_charge_state don't have an extra timestep anymore.
  • Renamed class SystemModel to FlowSystemModel
  • Renamed class Model to Submodel
  • Renamed mode parameter in plotting methods to style
  • Renamed investment binary variable is_invested to invested in InvestmentModel
  • Calculation.do_modeling() now returns the Calculation object instead of its linopy.Model. Callers that previously accessed the linopy model directly should now use calculation.do_modeling().model instead of calculation.do_modeling().

♻️ Changed

  • FlowSystems cannot be shared across multiple Calculations anymore. A copy of the FlowSystem is created instead, making every Calculation independent
  • Each Subcalculation in SegmentedCalculation now has its own distinct FlowSystem object
  • Type system overhaul - added clear separation between temporal and non-temporal data throughout codebase for better clarity
  • Enhanced FlowSystem interface with improved __repr__() and __str__() methods
  • Improved Model Structure - Views and organisation is now divided into:
    • Model: The main Model (linopy.Model) that is used to create and store the variables and constraints for the FlowSystem.
    • Submodel: The base class for all submodels. Each is a subset of the Model, for simpler access and clearer code.
  • Made docstrings in config.py more compact and easier to read
  • Improved format handling in configuration module
  • Enhanced console output to support both stdout and stderr stream selection
  • Added show_logger_name parameter to CONFIG.Logging for displaying logger names in messages

🗑️ Deprecated

  • The agg_group and agg_weight parameters of TimeSeriesData are deprecated and will be removed in a future version. Use aggregation_group and aggregation_weight instead.
  • The active_timesteps parameter of Calculation is deprecated and will be removed in a future version. Use the new sel(time=...) method on the FlowSystem instead.
  • The assignment of Bus Objects to Flow.bus is deprecated and will be removed in a future version. Use the label of the Bus instead.
  • The usage of Effects objects in Dicts to assign shares to Effects is deprecated and will be removed in a future version. Use the label of the Effect instead.
  • InvestParameters parameters renamed for improved clarity around investment and retirement effects:
    • fix_effects → effects_of_investment
    • specific_effects → effects_of_investment_per_size
    • divest_effects → effects_of_retirement
    • piecewise_effects → piecewise_effects_of_investment
  • Effect parameters renamed:
    • minimum_investment → minimum_periodic
    • maximum_investment → maximum_periodic
    • minimum_operation → minimum_temporal
    • maximum_operation → maximum_temporal
    • minimum_operation_per_hour → minimum_per_hour
    • maximum_operation_per_hour → maximum_per_hour
  • Component parameters renamed:
    • Source.source → Source.outputs
    • Sink.sink → Sink.inputs
    • SourceAndSink.source → SourceAndSink.outputs
    • SourceAndSink.sink → SourceAndSink.inputs
    • SourceAndSink.prevent_simultaneous_sink_and_source → SourceAndSink.prevent_simultaneous_flow_rates

🔥 Removed

  • Effect share parameters: The old specific_share_to_other_effects_* parameters were replaced WITHOUT DEPRECATION
    • specific_share_to_other_effects_operation → share_from_temporal (with inverted direction)
    • specific_share_to_other_effects_invest → share_from_periodic (with inverted direction)

🐛 Fixed

  • Enhanced NetCDF I/O with proper attribute preservation for DataArrays
  • Improved error handling and validation in serialization processes
  • Better type consistency across all framework components
  • Added extra validation in config.py to improve error handling

📝 Docs

  • Reorganized mathematical notation docs: moved to lowercase mathematical-notation/ with subdirectories (elements/, features/, modeling-patterns/)
  • Added comprehensive documentation pages: dimensions.md (time/period/scenario), effects-penalty-objective.md, modeling patterns
  • Enhanced all element pages with implementation details, cross-references, and "See Also" sections
  • Rewrote README and landing page with clearer vision, roadmap, and universal applicability emphasis
  • Removed deprecated docs/SUMMARY.md, updated mkdocs.yml for new structure
  • Tightened docstrings in core modules with better cross-referencing
  • Added recipes section to docs

🚧 Known Issues

  • IO for single Interfaces/Elements to Datasets might not work properly if the Interface/Element is not part of a fully transformed and connected FlowSystem. This arises from Numeric Data not being stored as xr.DataArray by the user. To avoid this, always use the to_dataset() on Elements inside a FlowSystem that's connected and transformed.

👷 Development

  • Centralized deprecation pattern: Added _handle_deprecated_kwarg() helper method to Interface base class that provides reusable deprecation handling with consistent warnings, conflict detection, and optional value transformation. Applied across 5 classes (InvestParameters, Source, Sink, SourceAndSink, Effect) reducing deprecation boilerplate by 72%.
  • FlowSystem data management simplified - removed time_series_collection pattern in favor of direct timestep properties
  • Change modeling hierarchy to allow for more flexibility in future development. This leads to minimal changes in the access and creation of Submodels and their variables.
  • Added new module .modeling that contains modeling primitives and utilities
  • Clearer separation between the main Model and "Submodels"
  • Improved access to the Submodels and their variables, constraints and submodels
  • Added __repr__() for Submodels to easily inspect its content
  • Enhanced data handling methods
    • fit_to_model_coords() method for data alignment
    • fit_effects_to_model_coords() method for effect data processing
    • connect_and_transform() method replacing several operations
  • Testing improvements: Eliminated warnings during test execution
    • Updated deprecated code patterns in tests and examples (e.g., sink/source → inputs/outputs, 'H' → 'h' frequency)
    • Refactored plotting logic to handle test environments explicitly with non-interactive backends
    • Added comprehensive warning filters in __init__.py and pyproject.toml to suppress third-party library warnings
    • Improved test fixtures with proper figure cleanup to prevent memory leaks
    • Enhanced backend detection and handling in plotting.py for both Matplotlib and Plotly
    • Always run dependent tests in order

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