Houdini 22.0 Executing tasks with PDG/TOPs

pdg package

The classes and functions in the Python pdg package for working with dependency graphs.

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Package-level functions

The following top-level attribute functions are designed to be used in parameters with Python expressions. You can use pdg.workItem() to get the current work item object in a Python expression, and use it to access other methods and properties from the pdg.WorkItem class. For example, the Python expressions pdg.workItem().floatAttribValue("foo", 1) and pdg.WorkItem()["foo"][1] are equivalent to the HScript expression @foo.1.

API

attributes

cooking

customtypes

  • pdg.Dictionary

    Wraps a nested dictionary object in Python, used with Dictionary Array attributes

data

debugging

events

exceptions

  • pdg.AttribError

    Generic exception raised when an error occurs when accessing work item attributes

  • pdg.CookError

    Generic exception raised when an error running the graph.

  • pdg.ServiceError

    Generic exception raised when an error occurs during a PDG service manager operation

expressions

  • pdg.EvaluationContext

    A module with global functions that operate on the thread-local evaluation context

internal

nodes

schedulers

services

types

workitems

Executing tasks with PDG/TOPs

Basics

Beginner Tutorials

Next steps

Reference

  • All TOPs nodes

    TOP nodes define a workflow where data is fed into the network, turned into work items and manipulated by different nodes. Many nodes represent external processes that can be run on the local machine or a server farm.

  • Processor Node Callbacks

    Processor nodes generate work items that can be executed by a scheduler

  • Partitioner Node Callbacks

    Partitioner nodes group multiple upstream work items into single partitions.

  • Scheduler Node Callbacks

    Scheduler nodes execute work items

  • Custom File Tags and Handlers

    PDG uses file tags to determine the type of an output file.

  • Python API

    The classes and functions in the Python pdg package for working with dependency graphs.

  • Job API

    Python API used by job scripts.

  • Utility API

    The classes and functions in the Python pdgutils package are intended for use both in PDG nodes and scripts as well as out-of-process job scripts.