Overview of hec-python-library Classes

Locations:

• Location Class

Parameters:

• General: Parameter Class

• Elevations: ElevParameter Class

• Types: ParameterType Class

Times:

All time-related classes have a values read/write property that is a list of six integers [1] representing:

• year(s)

• month(s)

• day(s)

• hour(s)

• minute(s)

• second(s)

• Instances: HecTime Class

• Periods:

  • Generic: TimeSpan Class

  • Value Recurrence: Interval Class

  • Value Duration: Duration Class

Values:

• Quantity: UnitQuantity Class

• Quality: Quality Class

TimeSeries:

• Individual Values: TimeSeriesValue Class

• Sequence of Values: TimeSeries Class

Ratings:

Object Types

Object Type	CWMS Store	CWMS Retrieve	HEC-DSS Store/Retrieve	XML Store/Retrieve
Individual Ratings	No	No	No	Yes
Rating Sets	No	Yes	Yes	Yes
Paired Data	No	No	Yes	No

Naming

Individual ratings and ratings sets (but not paired data) share a naming convention that references metadata objects for the ratings/sets [2]. There are four parts (separated by dot (.) characters) to this naming convention:

1. The location identifier

2. The parameters identifier:

1. an ordered list of independent parameters, separated by comma (,) characters

2. a semicolon (;) character

3. the dependent parameter

3. The template version

4. The specification version

Parts 2-3 (the rating template identifier) references a RatingTemplate with the specified identifier.

Parts 1-4 (the rating specification identifier) references a RatingSpecification with the specified identifier.

Paired data objects use the normal HEC-DSS pathname convention for paired data.

Office

Rating sets and all included objects (individual ratings, specifications, templates) require an office identifier. Therefore, when retrieving them from a data store the data store must have a default office specified or the retrieve(...) method must use the office= parameter.

Methods

All ratings objects (including paired data objects) have the following methods:

• rate(...) for transforming independent parameter values to dependent parameter values

• reverse_rate(...) for transforming dependent parameter values to independent parameter values. Not all classes support reverse_rate(...)

Classes

All classes directly related to ratings objects are:

• RatingTemplate Class

• RatingSpecification Class

• AbstractRating Class

• SimpleRating Class

• TableRating Class

• ExpressionRating: (not implemented yet)

• VirtualRating: (not implemented yet)

• TransitionalRating: (not implemented yet)

• AbstractRatingSet Class

• LocalRatingSet Class

• ReferenceRatingSet Class

• PairedData Class

Data Stores:

• AbstractDataStore: AbstractDataStore Class

• CwmsDataStore: CwmsDataStore Class

• DssDataStore: DssDataStore Class

[1]

For TimeSpan, Interval, and Duration, the months position may also be a Fraction with denominator of 2 or 3 to support the Semi-Month and Tri-Month intervals in HEC-DSS

[2]

Even when using HEC-DSS files to store rating sets. See this note.