Base class

type ScenarioInitCallback = Callable[[Scenario, int], None]

class Scenario

A scenario is a generator of World.

Sub-classes should override init_world() with a custom initialization that is performed each time a world is sampled (e.g., during an experiment).

They can also be customized by adding groups using add_group() and/or initializers using add_init, although these are not exposed to YAML.

class Group

A group of agents that can be generated and added to the world.

add_to_world(world: navground.sim.NativeWorld, seed: int | None = None) → None

Generate and add agents to the world.

Parameters:

• world – The world

• seed – An optional random seed

add_group(group: object) → None

Adds a group.

Parameters:

group – The group

add_init(initializer: Callable) → str

Adds a world initializer.

Parameters:

initializer – The initializer

Returns:

The associated key

add_property_sampler(name: str, value: navground::sim::PropertySampler) → None

Adds a property sampler.

Parameters:

• name – The name of the property

• value – The sampler

apply_inits(world: navground.sim.NativeWorld) → None

Applies the initializers from inits

Should be called after init_world() to complete the initialization, as make_world does automatically.

Parameters:

world – The world

clear_groups() → None

Remove all groups

clear_inits() → None

Removed all initializers

clear_property_samplers() → None

Clears the property samplers

dump() → str

Dumps the object to a YAML-string.

Returns:

The YAML representation

Return type:

str

get(name: str) → bool | int | float | str | Vector2 | list[bool] | list[int] | list[float] | list[str] | list[Vector2]

Gets the value of the specified property.

Parameters:

name – The name of the property

Raise:

std::runtime_error A runtime error if no property is found.

Returns:

The value of the property

get_group(index: int) → navground.sim.Scenario.Group

Gets a group.

Parameters:

index – The index

Returns:

The group or null if the index is not defined.

get_property_type_name(name: str) → str

Gets the type of a property.

Parameters:

name – The name of the property

Returns:

The property type name or an empty string if the property is not defined.

has(name: str) → bool

Checks whether a property exists.

Parameters:

name – The name of the property

Returns:

True if the property exists

static has_type(name: str) → bool

Check whether a type name has been registered.

Parameters:

type – The associated type name.

Returns:

True if the type name has been registered.

init_world(world: navground.sim.NativeWorld, seed: int | None = None) → None

Initializes the world.

Users can specialize this method to specialize a scenario but should call make_world when creating a world.

Parameters:

• world – The world

• seed – The random seed

static load(value: str) → object

Load a scenario from a YAML string.

Parameters:

value – the YAML string.

Returns:

The loaded scenario or None if loading fails.

Return type:

Scenario| None

static make_type(name: str) → object

Create an object of a sub-class selected by name.

Parameters:

type – The associated type name.

Returns:

An object of a registered sub-class or None in case the desired name is not found.

make_world(seed: int | None = None) → object

Creates and initialize a world.

Parameters:

seed – The random seed

static register_schema() → object

Returns the json-schema that includes registered components.

Returns:

“anyOf” json-schema of all registered components.

Return type:

dict[str, typing.Any]

remove_group(group: object) → None

Remove the added group.

Parameters:

group – The group

remove_group_at_index(index: int) → None

Remove the added group.

Parameters:

index – The index

remove_init(key: str) → None

Remove the last added world initializer.

Parameters:

key – The key

remove_property_sampler(name: str) → None

Removes a property sampler.

Parameters:

name – The name of the property

static schema(reference_register_schema: bool = True, type: str | None = None) → object

Returns the json-schema of a component

Returns an empty dictionary if a not registered type is requested.

Parameters:

• reference_register_schema – Whether to reference registered components schema in the base class schema.

• type (str) – An optional registered type. If not specified, it returns the schema of the base class.

Returns:

A json-schema of the registered class

Return type:

dict[str, typing.Any]

set(name: str, value: bool | int | float | str | Vector2 | list[bool] | list[int] | list[float] | list[str] | list[Vector2]) → None

Set the value of a named property. Fails silently if no property can be found or if the value has a non-compatible type.

Parameters:

• name – The name of the property

• value – The desired value for the property

set_attributes(world: navground.sim.NativeWorld) → None

Sets world attributes from scenario properties.

Sets an attribute with the current value for each (registered) property.

Parameters:

world – The world

set_init(key: str, initializer: Callable) → None

Sets a world initializer.

Parameters:

• key – The key

• initializer – The initializer

set_yaml(value: str) → None

Sets the yaml representation

property bounding_box

Type:

Optional[navground.sim.BoundingBox]

An optional bounding box

property groups

Type:

list[navground.sim.Scenario.Group]

The groups.

property inits

Type:

dict[str, Callable[[navground.sim.NativeWorld, Optional[int]], None]]

The world initializers.

property obstacles

Type:

list[navground.core.Disc]

Obstacles

property properties

Type:

dict[str, navground.core.Property]

The registered properties

property property_samplers

Type:

dict[str, navground::sim::PropertySampler]

Returns the samplers that this scenario uses for its properties.

property type

Type:

str

The name associated to the type of an object

property walls

Type:

list[navground.core.LineSegment]

Walls to add