Graph#

class langchain_core.runnables.graph.Graph(nodes: ~typing.Dict[str, ~langchain_core.runnables.graph.Node] = <factory>, edges: ~typing.List[~langchain_core.runnables.graph.Edge] = <factory>)[source]#

Graph of nodes and edges.

Parameters:

nodes (Dict[str, Node]) – Dictionary of nodes in the graph. Defaults to an empty dictionary.
edges (List[Edge]) – List of edges in the graph. Defaults to an empty list.

Attributes

Methods

`__init__`([nodes, edges])
`add_edge`(source, target[, data, conditional])	Add an edge to the graph and return it.
`add_node`(data[, id, metadata])	Add a node to the graph and return it.
`draw_ascii`()	Draw the graph as an ASCII art string.
`draw_mermaid`(*[, with_styles, curve_style, ...])	Draw the graph as a Mermaid syntax string.
`draw_mermaid_png`(*[, curve_style, ...])	Draw the graph as a PNG image using Mermaid.
`draw_png`()	Draw the graph as a PNG image.
`extend`(graph, *[, prefix])	Add all nodes and edges from another graph.
`first_node`()	Find the single node that is not a target of any edge.
`last_node`()	Find the single node that is not a source of any edge.
`next_id`()	Return a new unique node identifier that can be used to add a node to the graph.
`print_ascii`()	Print the graph as an ASCII art string.
`reid`()	Return a new graph with all nodes re-identified, using their unique, readable names where possible.
`remove_node`(node)	Remove a node from the graph and all edges connected to it.
`to_json`(*[, with_schemas])	Convert the graph to a JSON-serializable format.
`trim_first_node`()	Remove the first node if it exists and has a single outgoing edge, i.e., if removing it would not leave the graph without a "first" node.
`trim_last_node`()	Remove the last node if it exists and has a single incoming edge, i.e., if removing it would not leave the graph without a "last" node.

__init__(nodes: ~typing.Dict[str, ~langchain_core.runnables.graph.Node] = <factory>, edges: ~typing.List[~langchain_core.runnables.graph.Edge] = <factory>) → None#

Parameters:

nodes (Dict[str, Node]) –
edges (List[Edge]) –

Return type:

None

add_edge(source: Node, target: Node, data: Stringifiable | None = None, conditional: bool = False) → Edge[source]#

Add an edge to the graph and return it.

Parameters:

source (Node) – The source node of the edge.
target (Node) – The target node of the edge.
data (Stringifiable | None) – Optional data associated with the edge. Defaults to None.
conditional (bool) – Whether the edge is conditional. Defaults to False.

Returns:

The edge that was added to the graph.

Raises:

ValueError – If the source or target node is not in the graph.

Return type:

Edge

add_node(data: Type[BaseModel] | RunnableType, id: str | None = None, *, metadata: Dict[str, Any] | None = None) → Node[source]#

Add a node to the graph and return it.

Parameters:

data (Union[Type[BaseModel], RunnableType]) – The data of the node.
id (Optional[str]) – The id of the node. Defaults to None.
metadata (Optional[Dict[str, Any]]) – Optional metadata for the node. Defaults to None.

Returns:

The node that was added to the graph.

Raises:

ValueError – If a node with the same id already exists.

Return type:

Node

draw_ascii() → str[source]#

Draw the graph as an ASCII art string.

Return type:: str

draw_mermaid(*, with_styles: bool = True, curve_style: CurveStyle = CurveStyle.LINEAR, node_colors: NodeStyles = NodeStyles(default='fill:#f2f0ff,line-height:1.2', first='fill-opacity:0', last='fill:#bfb6fc'), wrap_label_n_words: int = 9) → str[source]#

Draw the graph as a Mermaid syntax string.

Parameters:

with_styles (bool) – Whether to include styles in the syntax. Defaults to True.
curve_style (CurveStyle) – The style of the edges. Defaults to CurveStyle.LINEAR.
node_colors (NodeStyles) – The colors of the nodes. Defaults to NodeStyles().
wrap_label_n_words (int) – The number of words to wrap the node labels at. Defaults to 9.

Returns:

The Mermaid syntax string.

Return type:

str

draw_mermaid_png(*, curve_style: CurveStyle = CurveStyle.LINEAR, node_colors: NodeStyles = NodeStyles(default='fill:#f2f0ff,line-height:1.2', first='fill-opacity:0', last='fill:#bfb6fc'), wrap_label_n_words: int = 9, output_file_path: str | None = None, draw_method: MermaidDrawMethod = MermaidDrawMethod.API, background_color: str = 'white', padding: int = 10) → bytes[source]#

Draw the graph as a PNG image using Mermaid.

Parameters:

curve_style (CurveStyle) – The style of the edges. Defaults to CurveStyle.LINEAR.
node_colors (NodeStyles) – The colors of the nodes. Defaults to NodeStyles().
wrap_label_n_words (int) – The number of words to wrap the node labels at. Defaults to 9.
output_file_path (str | None) – The path to save the image to. If None, the image is not saved. Defaults to None.
draw_method (MermaidDrawMethod) – The method to use to draw the graph. Defaults to MermaidDrawMethod.API.
background_color (str) – The color of the background. Defaults to “white”.
padding (int) – The padding around the graph. Defaults to 10.

Returns:

The PNG image as bytes.

Return type:

bytes

draw_png(output_file_path: str, fontname: str | None = None, labels: LabelsDict | None = None) → None[source]#

draw_png(output_file_path: None, fontname: str | None = None, labels: LabelsDict | None = None) → bytes

Draw the graph as a PNG image.

Parameters:

output_file_path – The path to save the image to. If None, the image is not saved. Defaults to None.
fontname – The name of the font to use. Defaults to None.
labels – Optional labels for nodes and edges in the graph. Defaults to None.

Returns:

The PNG image as bytes if output_file_path is None, None otherwise.

extend(graph: Graph, *, prefix: str = '') → Tuple[Node | None, Node | None][source]#

Add all nodes and edges from another graph. Note this doesn’t check for duplicates, nor does it connect the graphs.

Parameters:

graph (Graph) – The graph to add.
prefix (str) – The prefix to add to the node ids. Defaults to “”.

Returns:

A tuple of the first and last nodes of the subgraph.

Return type:

Tuple[Node | None, Node | None]

first_node() → Node | None[source]#

Find the single node that is not a target of any edge. If there is no such node, or there are multiple, return None. When drawing the graph, this node would be the origin.

Return type:: Node | None

last_node() → Node | None[source]#

Find the single node that is not a source of any edge. If there is no such node, or there are multiple, return None. When drawing the graph, this node would be the destination.

Return type:: Node | None

next_id() → str[source]#

Return a new unique node identifier that can be used to add a node to the graph.

Return type:: str

print_ascii() → None[source]#

Print the graph as an ASCII art string.

Return type:: None

reid() → Graph[source]#

Return a new graph with all nodes re-identified, using their unique, readable names where possible.

Return type:: Graph

remove_node(node: Node) → None[source]#

Remove a node from the graph and all edges connected to it.

Parameters:: node (Node) – The node to remove.
Return type:: None

to_json(*, with_schemas: bool = False) → Dict[str, List[Dict[str, Any]]][source]#

Convert the graph to a JSON-serializable format.

Parameters:: with_schemas (bool) – Whether to include the schemas of the nodes if they are Pydantic models. Defaults to False.
Returns:: A dictionary with the nodes and edges of the graph.
Return type:: Dict[str, List[Dict[str, Any]]]

trim_first_node() → None[source]#

Remove the first node if it exists and has a single outgoing edge, i.e., if removing it would not leave the graph without a “first” node.

Return type:: None

trim_last_node() → None[source]#

Remove the last node if it exists and has a single incoming edge, i.e., if removing it would not leave the graph without a “last” node.

Return type:: None