Color Management¶

flixOpt provides centralized color management to ensure consistent colors across all visualizations.

Carriers¶

Carriers define energy or material types with associated colors. Built-in carriers are available in CONFIG.Carriers:

Carrier	Color	Hex
`electricity`		`#FECB52`
`heat`		`#D62728`
`gas`		`#1F77B4`
`hydrogen`		`#9467BD`
`fuel`		`#8C564B`
`biomass`		`#2CA02C`

Assign carriers to buses for automatic coloring:

heat_bus = fx.Bus('HeatNetwork', carrier='heat')
elec_bus = fx.Bus('Grid', carrier='electricity')

# Plots automatically use carrier colors
flow_system.statistics.plot.sankey.flows()

Custom Carriers¶

Register custom carriers on your FlowSystem:

biogas = fx.Carrier('biogas', color='#228B22', unit='kW', description='Biogas fuel')

flow_system.add_carrier(biogas)

Setting Component Colors¶

At Construction¶

boiler = fx.LinearConverter('Boiler', ..., color='#D35400')
storage = fx.Storage('Battery', ..., color='green')

Via Topology Accessor¶

# Single component
flow_system.topology.set_component_color('Boiler', '#D35400')

# Multiple components
flow_system.topology.set_component_colors({
    'Boiler': '#D35400',
    'CHP': '#8E44AD',
    'HeatPump': '#27AE60',
})

# Apply a colorscale to all components
flow_system.topology.set_component_colors('turbo')

# Apply colorscales to groups
flow_system.topology.set_component_colors({
    'Oranges': ['Solar1', 'Solar2', 'Solar3'],
    'Blues': ['Wind1', 'Wind2'],
})

Carrier Colors¶

flow_system.topology.set_carrier_color('electricity', '#FECB52')

Context-Aware Coloring¶

Plot colors are automatically resolved based on context:

Bus balance plots: Flows colored by their parent component
Component balance plots: Flows colored by their connected bus/carrier
Sankey diagrams: Buses use carrier colors, components use configured colors

# Plotting a bus → flows colored by component
flow_system.statistics.plot.balance('ElectricityBus')

# Plotting a component → flows colored by carrier
flow_system.statistics.plot.balance('CHP')

Color Resolution Priority¶

Colors are resolved in this order:

Explicit colors passed to plot methods (always override)
Component colors set via topology or at construction
Carrier colors for buses
Default colorscale (CONFIG.Plotting.default_qualitative_colorscale)

Persistence¶

Colors are automatically saved and restored with the FlowSystem:

# Colors are persisted
flow_system.to_netcdf('my_system.nc')

# And restored
loaded = fx.FlowSystem.from_netcdf('my_system.nc')
loaded.topology.component_colors  # Colors preserved

Accessing Colors Programmatically¶

The topology accessor provides cached dictionaries:

flow_system.topology.carrier_colors   # {'electricity': '#FECB52', ...}
flow_system.topology.component_colors # {'Boiler': '#1f77b4', ...}
flow_system.topology.bus_colors       # {'ElecBus': '#FECB52', ...}

You can also inspect individual components:

for comp in flow_system.components.values():
    print(f"{comp.label}: {comp.color}")

Auto-Assignment¶

Components without explicit colors are automatically assigned colors when you call optimize() or connect_and_transform(). The colors come from CONFIG.Plotting.default_qualitative_colorscale (default: 'plotly').