kedro.pipeline.Pipeline

class kedro.pipeline.Pipeline(nodes, *, tags=None)[source]

A Pipeline defined as a collection of Node objects. This class treats nodes as part of a graph representation and provides inputs, outputs and execution order.

Attributes

grouped_nodes

Return a list of the pipeline nodes in topologically ordered groups, i.e. if node A needs to be run before node B, it will appear in an earlier group.

node_dependencies

All dependencies of nodes where the first Node has a direct dependency on the second Node.

nodes

Return a list of the pipeline nodes in topological order, i.e. if node A needs to be run before node B, it will appear earlier in the list.

Methods

all_inputs()

All inputs for all nodes in the pipeline.

all_outputs()

All outputs of all nodes in the pipeline.

data_sets()

The names of all data sets used by the Pipeline, including inputs and outputs.

describe([names_only])

Obtain the order of execution and expected free input variables in a loggable pre-formatted string.

filter([tags, from_nodes, to_nodes, …])

Creates a new Pipeline object with the nodes that meet all of the specified filtering conditions.

from_inputs(*inputs)

Create a new Pipeline object with the nodes which depend directly or transitively on the provided inputs.

from_nodes(*node_names)

Create a new Pipeline object with the nodes which depend directly or transitively on the provided nodes.

inputs()

The names of free inputs that must be provided at runtime so that the pipeline is runnable.

only_nodes(*node_names)

Create a new Pipeline which will contain only the specified nodes by name.

only_nodes_with_inputs(*inputs)

Create a new Pipeline object with the nodes which depend directly on the provided inputs.

only_nodes_with_namespace(node_namespace)

Creates a new Pipeline containing only nodes with the specified namespace.

only_nodes_with_outputs(*outputs)

Create a new Pipeline object with the nodes which are directly required to produce the provided outputs.

only_nodes_with_tags(*tags)

Creates a new Pipeline object with the nodes which contain any of the provided tags.

outputs()

The names of outputs produced when the whole pipeline is run.

tag(tags)

Tags all the nodes in the pipeline.

to_json()

Return a json representation of the pipeline.

to_nodes(*node_names)

Create a new Pipeline object with the nodes required directly or transitively by the provided nodes.

to_outputs(*outputs)

Create a new Pipeline object with the nodes which are directly or transitively required to produce the provided outputs.

__init__(nodes, *, tags=None)[source]

Initialise Pipeline with a list of Node instances.

Parameters
  • nodes (Iterable[Union[Node, Pipeline]]) – The iterable of nodes the Pipeline will be made of. If you provide pipelines among the list of nodes, those pipelines will be expanded and all their nodes will become part of this new pipeline.

  • tags (Union[str, Iterable[str], None]) – Optional set of tags to be applied to all the pipeline nodes.

Raises
  • ValueError – When an empty list of nodes is provided, or when not all nodes have unique names.

  • CircularDependencyError – When visiting all the nodes is not possible due to the existence of a circular dependency.

  • OutputNotUniqueError – When multiple Node instances produce the same output.

  • ConfirmNotUniqueError – When multiple Node instances attempt to confirm the same dataset.

Example:

from kedro.pipeline import Pipeline
from kedro.pipeline import node

# In the following scenario first_ds and second_ds
# are data sets provided by io. Pipeline will pass these
# data sets to first_node function and provides the result
# to the second_node as input.

def first_node(first_ds, second_ds):
    return dict(third_ds=first_ds+second_ds)

def second_node(third_ds):
    return third_ds

pipeline = Pipeline([
    node(first_node, ['first_ds', 'second_ds'], ['third_ds']),
    node(second_node, dict(third_ds='third_ds'), 'fourth_ds')])

pipeline.describe()
all_inputs()[source]

All inputs for all nodes in the pipeline.

Return type

Set[str]

Returns

All node input names as a Set.

all_outputs()[source]

All outputs of all nodes in the pipeline.

Return type

Set[str]

Returns

All node outputs.

data_sets()[source]

The names of all data sets used by the Pipeline, including inputs and outputs.

Return type

Set[str]

Returns

The set of all pipeline data sets.

describe(names_only=True)[source]

Obtain the order of execution and expected free input variables in a loggable pre-formatted string. The order of nodes matches the order of execution given by the topological sort.

Parameters

names_only (bool) – The flag to describe names_only pipeline with just node names.

Example:

pipeline = Pipeline([ ... ])

logger = logging.getLogger(__name__)

logger.info(pipeline.describe())

After invocation the following will be printed as an info level log statement:

#### Pipeline execution order ####
Inputs: C, D

func1([C]) -> [A]
func2([D]) -> [B]
func3([A, D]) -> [E]

Outputs: B, E
##################################
Return type

str

Returns

The pipeline description as a formatted string.

filter(tags=None, from_nodes=None, to_nodes=None, node_names=None, from_inputs=None, to_outputs=None, node_namespace=None)[source]

Creates a new Pipeline object with the nodes that meet all of the specified filtering conditions.

The new pipeline object is the intersection of pipelines that meet each filtering condition. This is distinct from chaining multiple filters together.

Parameters
  • tags (Optional[Iterable[str]]) – A list of node tags which should be used to lookup the nodes of the new Pipeline.

  • from_nodes (Optional[Iterable[str]]) – A list of node names which should be used as a starting point of the new Pipeline.

  • to_nodes (Optional[Iterable[str]]) – A list of node names which should be used as an end point of the new Pipeline.

  • node_names (Optional[Iterable[str]]) – A list of node names which should be selected for the new Pipeline.

  • from_inputs (Optional[Iterable[str]]) – A list of inputs which should be used as a starting point of the new Pipeline

  • to_outputs (Optional[Iterable[str]]) – A list of outputs which should be the final outputs of the new Pipeline.

  • node_namespace (Optional[str]) – One node namespace which should be used to select nodes in the new Pipeline.

Return type

Pipeline

Returns

A new Pipeline object with nodes that meet all of the specified

filtering conditions.

Raises

ValueError – The filtered Pipeline has no nodes.

Example:

pipeline = Pipeline(
    [
        node(func, "A", "B", name="node1"),
        node(func, "B", "C", name="node2"),
        node(func, "C", "D", name="node3"),
    ]
)
pipeline.filter(node_names=["node1", "node3"], from_inputs=["A"])
# Gives a new pipeline object containing node1 and node3.
from_inputs(*inputs)[source]

Create a new Pipeline object with the nodes which depend directly or transitively on the provided inputs. If provided a name, but no format, for a transcoded input, it includes all the nodes that use inputs with that name, otherwise it matches to the fully-qualified name only (i.e. name@format).

Parameters

*inputs – A list of inputs which should be used as a starting point of the new Pipeline

Raises

ValueError – Raised when any of the given inputs do not exist in the Pipeline object.

Return type

Pipeline

Returns

A new Pipeline object, containing a subset of the

nodes of the current one such that only nodes depending directly or transitively on the provided inputs are being copied.

from_nodes(*node_names)[source]

Create a new Pipeline object with the nodes which depend directly or transitively on the provided nodes.

Parameters

*node_names – A list of node_names which should be used as a starting point of the new Pipeline.

Raises

ValueError – Raised when any of the given names do not exist in the Pipeline object.

Return type

Pipeline

Returns

A new Pipeline object, containing a subset of the nodes of

the current one such that only nodes depending directly or transitively on the provided nodes are being copied.

property grouped_nodes

Return a list of the pipeline nodes in topologically ordered groups, i.e. if node A needs to be run before node B, it will appear in an earlier group.

Return type

List[Set[Node]]

Returns

The pipeline nodes in topologically ordered groups.

inputs()[source]

The names of free inputs that must be provided at runtime so that the pipeline is runnable. Does not include intermediate inputs which are produced and consumed by the inner pipeline nodes. Resolves transcoded names where necessary.

Return type

Set[str]

Returns

The set of free input names needed by the pipeline.

property node_dependencies

All dependencies of nodes where the first Node has a direct dependency on the second Node.

Return type

Dict[Node, Set[Node]]

Returns

Dictionary where keys are nodes and values are sets made up of their parent nodes. Independent nodes have this as empty sets.

property nodes

Return a list of the pipeline nodes in topological order, i.e. if node A needs to be run before node B, it will appear earlier in the list.

Return type

List[Node]

Returns

The list of all pipeline nodes in topological order.

only_nodes(*node_names)[source]

Create a new Pipeline which will contain only the specified nodes by name.

Parameters

*node_names – One or more node names. The returned Pipeline will only contain these nodes.

Raises

ValueError – When some invalid node name is given.

Return type

Pipeline

Returns

A new Pipeline, containing only nodes.

only_nodes_with_inputs(*inputs)[source]

Create a new Pipeline object with the nodes which depend directly on the provided inputs. If provided a name, but no format, for a transcoded input, it includes all the nodes that use inputs with that name, otherwise it matches to the fully-qualified name only (i.e. name@format).

Parameters

*inputs – A list of inputs which should be used as a starting point of the new Pipeline.

Raises

ValueError – Raised when any of the given inputs do not exist in the Pipeline object.

Return type

Pipeline

Returns

A new Pipeline object, containing a subset of the

nodes of the current one such that only nodes depending directly on the provided inputs are being copied.

only_nodes_with_namespace(node_namespace)[source]

Creates a new Pipeline containing only nodes with the specified namespace.

Parameters

node_namespace (str) – One node namespace.

Raises

ValueError – When pipeline contains no nodes with the specified namespace.

Return type

Pipeline

Returns

A new Pipeline containing nodes with the specified namespace.

only_nodes_with_outputs(*outputs)[source]

Create a new Pipeline object with the nodes which are directly required to produce the provided outputs. If provided a name, but no format, for a transcoded dataset, it includes all the nodes that output to that name, otherwise it matches to the fully-qualified name only (i.e. name@format).

Parameters

*outputs – A list of outputs which should be the final outputs of the new Pipeline.

Raises

ValueError – Raised when any of the given outputs do not exist in the Pipeline object.

Return type

Pipeline

Returns

A new Pipeline object, containing a subset of the nodes of the current one such that only nodes which are directly required to produce the provided outputs are being copied.

only_nodes_with_tags(*tags)[source]

Creates a new Pipeline object with the nodes which contain any of the provided tags. The resulting Pipeline is empty if no tags are provided.

Parameters

*tags – A list of node tags which should be used to lookup the nodes of the new Pipeline.

Returns

A new Pipeline object, containing a subset of the

nodes of the current one such that only nodes containing any of the tags provided are being copied.

Return type

Pipeline

outputs()[source]

The names of outputs produced when the whole pipeline is run. Does not include intermediate outputs that are consumed by other pipeline nodes. Resolves transcoded names where necessary.

Return type

Set[str]

Returns

The set of final pipeline outputs.

tag(tags)[source]

Tags all the nodes in the pipeline.

Parameters

tags (Union[str, Iterable[str]]) – The tags to be added to the nodes.

Return type

Pipeline

Returns

New Pipeline object with nodes tagged.

to_json()[source]

Return a json representation of the pipeline.

to_nodes(*node_names)[source]

Create a new Pipeline object with the nodes required directly or transitively by the provided nodes.

Parameters

*node_names – A list of node_names which should be used as an end point of the new Pipeline.

Raises

ValueError – Raised when any of the given names do not exist in the Pipeline object.

Return type

Pipeline

Returns

A new Pipeline object, containing a subset of the nodes of the

current one such that only nodes required directly or transitively by the provided nodes are being copied.

to_outputs(*outputs)[source]

Create a new Pipeline object with the nodes which are directly or transitively required to produce the provided outputs. If provided a name, but no format, for a transcoded dataset, it includes all the nodes that output to that name, otherwise it matches to the fully-qualified name only (i.e. name@format).

Parameters

*outputs – A list of outputs which should be the final outputs of the new Pipeline.

Raises

ValueError – Raised when any of the given outputs do not exist in the Pipeline object.

Return type

Pipeline

Returns

A new Pipeline object, containing a subset of the nodes of the current one such that only nodes which are directly or transitively required to produce the provided outputs are being copied.