panel.pipeline module#

class panel.pipeline.Pipeline(stages=[], graph={}, **params)[source]#

Bases: Viewer

A Pipeline represents a directed graph of stages, which each return a panel object to render. A pipeline therefore represents a UI workflow of multiple linear or branching stages.

The Pipeline layout consists of a number of sub-components:

header:
- title: The name of the current stage.
- error: A field to display the error state.
- network: A network diagram representing the pipeline.
- buttons: All navigation buttons and selectors.
- prev_button: The button to go to the previous stage.
- prev_selector: The selector widget to select between previous branching stages.
- next_button: The button to go to the previous stage
- next_selector: The selector widget to select the next branching stages.
stage: The contents of the current pipeline stage.

By default any outputs of one stage annotated with the param.output decorator are fed into the next stage. Additionally, if the inherit_params parameter is set any parameters which are declared on both the previous and next stage are also inherited.

The stages are declared using the add_stage method and must each be given a unique name. By default any stages will simply be connected linearly, but an explicit graph can be declared using the define_graph method.

Methods

`add_stage`(name, stage, **kwargs)	Adds a new, named stage to the Pipeline.
`define_graph`(graph[, force])	Declares a custom graph structure for the Pipeline overriding the default linear flow.

Parameter Definitions

auto_advance = Boolean(default=False, label='Auto advance'): Whether to automatically advance if the ready parameter is True.
debug = Boolean(default=False, label='Debug'): Whether to raise errors, useful for debugging while building an application.
inherit_params = Boolean(default=True, label='Inherit params'): Whether parameters should be inherited between pipeline stages.
next_parameter = String(allow_None=True, label='Next parameter'): Parameter name to watch to switch between different branching stages
ready_parameter = String(allow_None=True, label='Ready parameter'): Parameter name to watch to check whether a stage is ready.
show_header = Boolean(default=True, label='Show header'): Whether to show the header with the title, network diagram, and buttons.

next = Action(label='Next')

previous = Action(label='Previous')

add_stage(name, stage, **kwargs)[source]#

Adds a new, named stage to the Pipeline.

Parameters:

name: str: A string name for the Pipeline stage
stage: param.Parameterized: A Parameterized object which represents the Pipeline stage.
**kwargs: dict: Additional arguments declaring the behavior of the stage.

define_graph(graph, force=False)[source]#

Declares a custom graph structure for the Pipeline overriding the default linear flow. The graph should be defined as an adjacency mapping.

Parameters:

graph: dict: Dictionary declaring the relationship between different pipeline stages. Should map from a single stage name to one or more stage names.