Attributes

In OPGEE the term “attributes” refers to a class of model parameters that are pre-defined with metadata (attribute definitions) and are class-specific, i.e., they related to Analysis, Field, Process, or subclasses of Process.

Attributes are central to the operation of both the “Smart Defaults” and Monte Carlo simulation (MCS) subsystems. This page provides a brief overview of how attributes are used in these subsystems. See the pages linked below for more information.

See opgee.attributes for the Python API and more detailed documentation.

Attribute Definitions

Attributes used in model description XML files must be defined in attributes.xml. Attempts to use undefined attributes results in a runtime exception.

Attributes are defined in {opgee}/etc/attributes.xml using the <AttrDefs> element. Definitions include the attribute type (text string, integer, floating point number, or one of defined set of choices, as well as default values and other metadata.

Simple Defaults

Attributes defined in {opgee}/etc/attributes.xml are set to their default value if a value is not provided explicitly in a model description XML file. Default values can be overridden in an MCS if a distribution is defined for the attribute. Explicitly set values are not replaced in an MCS.

Smart Defaults

Smart Defaults are functions that set the value of an attribute based on calculations using the values of other model attributes. The SmartDefault class stores information required to run a “smart default” function. Most Smart Defaults are defined in the Field class. See Smart Defaults for more information.

Monte Carlo Simulation

OPGEE’s Monte Carlo Simulation framework defines probability distributions for values of specific attributes. If the attribute value has been set explicitly in the model XML, the distribution is not applied. See Monte Carlo Simulation for more information.