Add FlowContainer for inputs/outputs by FBumann · Pull Request #587 · flixOpt/flixopt

FBumann · 2026-01-23T13:13:28Z

Summary

Replaces list[Flow] with FlowContainer for inputs, outputs, and flows attributes. Provides dual access by index (inputs[0]) or label (inputs['Q_th']).

Breaking Change

Use .values() for flow iteration: for flow in component.inputs.values():

Summary by CodeRabbit

New Features
- Introduced FlowContainer for flexible access to component and bus flows by index or label (e.g., inputs[0] or inputs['Q_th'])
- Added new flows property to components and buses for unified access to both inputs and outputs
Refactor
- Updated internal flow collection handling to use dict-based containers for improved access patterns

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…s done: Summary 1. Created FlowContainer Class (structure.py) - Added FlowContainer class that extends ContainerMixin - Uses flow.label_full as the key (e.g., 'Boiler(Q_th)') - Supports index-based access: inputs[0] - Supports label-based access: inputs['Boiler(Q_th)'] - Added __add__ method to ContainerMixin for concatenation 2. Updated Component Class (elements.py) - Changed inputs and outputs from list[Flow] to FlowContainer - Modified __init__ to accept both list[Flow] and dict[str, Flow] (for deserialization) - Updated _check_unique_flow_labels() and _connect_flows() to accept lists as parameters - FlowContainers are created after connecting flows (so label_full is correct) 3. Updated Bus Class (elements.py) - Changed inputs and outputs from list[Flow] to FlowContainer 4. Updated Iteration Patterns All iteration patterns were updated from: - for flow in self.inputs: → for flow in self.inputs.values(): - for flow in self.inputs + self.outputs: → for flow in (self.inputs + self.outputs).values(): Files updated: - elements.py (Component, Bus, BusModel, ComponentModel) - components.py (TransmissionModel, LinearConverterModel) - flow_system.py (flow population and network connection) - io.py (format_flow_details) - statistics_accessor.py (various plotting methods) - tests/deprecated/test_integration.py Usage Examples boiler = Boiler(label='Boiler', inputs=[Flow('Q_th', bus=heat_bus)]) # Both access methods work assert boiler.inputs[0] == boiler.inputs['Boiler(Q_th)'] assert len(boiler.inputs) == 1 # Iteration requires .values() for flow in boiler.inputs.values(): print(flow.label_full) # Concatenation works all_flows = boiler.inputs + boiler.outputs for flow in all_flows.values(): print(flow.label) All 1570 tests passed.

Added all_flows property to Component and Bus classes using itertools.chain: @Property def all_flows(self) -> Iterator[Flow]: """Iterate over all flows (inputs and outputs) without creating intermediate containers.""" return chain(self.inputs.values(), self.outputs.values()) Performance Improvement ┌─────────┬──────────────────────────────┬───────────────────────┐ │ Pattern │ Before │ After │ ├─────────┼──────────────────────────────┼───────────────────────┤ │ Memory │ O(n) - creates new container │ O(1) - iterator only │ ├─────────┼──────────────────────────────┼───────────────────────┤ │ Time │ O(n) - copies all elements │ O(1) - lazy iteration │ └─────────┴──────────────────────────────┴───────────────────────┘ Usage # Efficient iteration (no allocation) for flow in component.all_flows: ... # When you need a list (e.g., reusing multiple times) all_flows = list(component.all_flows) # Container concatenation still available when needed combined = component.inputs + component.outputs # Creates new FlowContainer Files Updated - elements.py - Added property, updated 8 iteration patterns - components.py - Updated 1 pattern - flow_system.py - Updated 3 patterns - statistics_accessor.py - Updated 1 pattern All 1570 tests pass.

1. FlowContainer now supports short-label access When all flows in a container belong to the same component, you can access by short label: # Both work for component.inputs, component.outputs, and component.flows: component.inputs['Boiler(Q_th)'] # Full label component.inputs['Q_th'] # Short label ✓ # The `in` operator also supports short labels: if 'Q_th' in component.flows: # Works! ... 2. Component.flows is now a FlowContainer (cached property) # Before (dict keyed by short label): component.flows: dict[str, Flow] # After (FlowContainer with full/short label access): component.flows: FlowContainer # cached_property API Summary ┌─────────────────────┬──────────────────────────────────────┐ │ Access Pattern │ Example │ ├─────────────────────┼──────────────────────────────────────┤ │ Full label │ component.flows['Boiler(Q_th)'] │ ├─────────────────────┼──────────────────────────────────────┤ │ Short label │ component.flows['Q_th'] │ ├─────────────────────┼──────────────────────────────────────┤ │ Index │ component.flows[0] │ ├─────────────────────┼──────────────────────────────────────┤ │ Membership │ 'Q_th' in component.flows │ ├─────────────────────┼──────────────────────────────────────┤ │ Iteration │ for flow in component.flows.values() │ ├─────────────────────┼──────────────────────────────────────┤ │ Efficient iteration │ for flow in component.all_flows │ └─────────────────────┴──────────────────────────────────────┘ Note: Short-label access only works when all flows in the container share the same component (which is always true for component.inputs, component.outputs, and component.flows).

coderabbitai · 2026-01-23T13:13:38Z

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📝 Walkthrough

Walkthrough

Unifies flow collections by introducing FlowContainer and replacing list-based inputs + outputs patterns with container-based access (e.g., .flows.values() / .inputs.values() / .outputs.values()), updating component/bus initialization, topology wiring, modeling, IO, statistics, and tests accordingly.

Changes

Cohort / File(s)	Summary
Flow container core `flixopt/structure.py`	Added `FlowContainer` supporting index/label access and improved membership; added `ContainerMixin.__add__` to concatenate containers.
Component & Bus declarations `flixopt/elements.py`	`Component.__init__` accepts `list` or `dict` for inputs/outputs; new `_connect_flows`, `flows` (FlowContainer) and `all_flows` properties; Bus updated to expose `flows`/`all_flows`.
Flow system wiring `flixopt/flow_system.py`	Replace iterations over `inputs + outputs` with `comp.flows.values()`; bus wiring switched from list appends to set `.add()` for bus.inputs/bus.outputs; updated topology/linking logic.
Models updated `flixopt/components.py`	TransmissionModel and LinearConverterModel updated to iterate/link over flow containers (`.flows.values()` / `.inputs.values()` / `.outputs.values()`) when building constraints.
I/O and statistics `flixopt/io.py`, `flixopt/statistics_accessor.py`	Iteration and labeling logic changed to use `.values()` on inputs/outputs and component/bus flow containers for plotting and effect-share calculations.
Tests `tests/deprecated/test_integration.py`	Adjusted test setup to iterate merged flow containers via `.values()` when building flow mappings.
Changelog `CHANGELOG.md`	Documented FlowContainer introduction and flow-access API changes.

Sequence Diagram(s)

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

Add FlowContainer for inputs/outputs #587 — Similar refactor replacing list-based flow handling with FlowContainer and updating models to use .values().
Feature/v3/several improvements #372 — Related changes touching TransmissionModel's loss handling and flow-iteration updates.

Suggested labels

v3.0.0

Poem

🐇 I hop through flows both short and long,
containers sing a tidy song,
indices, labels, all in line,
components link and models shine—
a little refactor, neat and strong.

🚥 Pre-merge checks | ✅ 1 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Description check	⚠️ Warning	The description is incomplete. It lacks the required template sections including Type of Change, Related Issues, Testing checklist, and the complete Checklist items.	Use the repository's pull request template and complete all required sections including Type of Change checkboxes, Related Issues, Testing status, and full Checklist.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: introducing FlowContainer for inputs/outputs attributes to provide dual access patterns.

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FBumann · 2026-01-23T14:09:21Z

@coderabbitai review

coderabbitai · 2026-01-23T14:09:31Z

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FBumann added 3 commits January 23, 2026 13:12

FBumann changed the title ~~Feature/containers~~Add FlowContainer for inputs/outputs with dual access (index + label)Jan 23, 2026

Remove all_flows and make bus.flows non cahced!
5cb8511

FBumann changed the title ~~Add FlowContainer for inputs/outputs with dual access (index + label)~~Add FlowContainer for inputs/outputsJan 23, 2026

Udpate Changelo
1787a6c

FBumann marked this pull request as ready for review January 23, 2026 14:45

FBumann merged commit 8e8fe5c into mainJan 23, 2026
7 of 8 checks passed

coderabbitaiBot mentioned this pull request Feb 16, 2026
Feature/element data classes+id+dataclasses #611
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9 tasks

coderabbitaiBot mentioned this pull request Jul 22, 2026
feat!: remove all overdue deprecated APIs (Optimization/Results, FlowSystem methods, kwarg shims) #741
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Add FlowContainer for inputs/outputs - #587

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