OpenDCS Algorithms - Resources

Algorithms Resources - Recap

There are a number of “Standard” or “Baseline” algorithms that come with OpenDCS when it is installed. These can be thought of as banked algorithms or functions that can be called upon when setting up a computation. These standard algorithms are generally basic arithmetic or time series manipulation or transformations. For example, the average algorithm (AverageAlgorithm)can be used to create a daily or monthly time series from an hourly or daily time series, respectively. In addition to simple arithmetic and transformations, there are some specific algorithms that are commonly used in water resources management. For example the incremental precipitation algorithm (IncrementalPrecip) can be called upon to calculate an incremental precipitation time series from a cumulative precipitation time series. Additionally there are also some algorithms that calculate flow based on various time series input.

This page is intended to provide further details and examples of the default algorithms. Nearly all of these algorithms have properties that can be set to tweak the way the algorithm is executed. For example, the properties can address time shifts, missing values, change how default upper and lower bounds are handled, etc. It is recommended to understand how the basic default algorithm behaves before advancing to editing the properties.

This page is divided into three sections:

1. OpenDCS Standard Algorithms

2. OpenDCS Custom Algorithms

3. OpenDCS Algorithm GUI Basics

As a recap, below is a table of algorithms that come with OpenDCS installs.

Type	Algorithm	Exec Class
Arithmetic or Transformation	AddToPrevious	decodes.tsdb.algo.AddToPrevious
	AverageAlgorithm	decodes.tsdb.algo.AverageAlgorithm
	ChooseOne	decodes.tsdb.algo.ChooseOne
	CopyAlgorithm	decodes.tsdb.algo.CopyAlgorithm
	CopyNoOverwrite	decodes.tsdb.algo.CopyNoOverwrite
	DisAggregate	decodes.tsdb.algo.DisAggregate
	FillForward	decodes.tsdb.algo.FillForward
	Resample	decodes.tsdb.algo.Resample
	RunningAverageAlgorithm	decodes.tsdb.algo.RunningAverageAlgorithm
	ScalarAdder	decodes.tsdb.algo.ScalerAdder
	SubSample	decodes.tsdb.algo.SubSample
	SumOverTimeAlgorithm	decodes.tsdb.algo.SumOverTimeAlgorithm
Hydrologic	BridgeClearance	decodes.tsdb.algo.BridgeClearance
	EstimatedInflow	decodes.tsdb.algo.EstimatedInflow
	IncrementalPrecip	decodes.tsdb.algo.IncrementalPrecip
	RdbRating	decodes.tsdb.algo.RdbRating
	TabRating	decodes.tsdb.algo.TabRating
	UsgsEquation	decodes.tsdb.algo.UsgsEquation
	VirtualGage	decodes.tsdb.algo.VirtualGage
	RelativeHumidity	decodes.tsdb.algo.RelativeHumidity
Arithmetic or Transformation (Hidden)	CentralRunningAverage
	Division
	GroupAdder
	Multiplication
	PeriodToDate
	Stat
Hydrologic (Hidden)	ExpressionParserAlgorithm
	FlowResIn
	WeightedWaterTemperature

The following two tables are the algorithms specific to CWMS or HDB.

Type	Algorithm	Exec Class
CWMS	CentralRunningAverage	decodes.cwms.rating.CwmsRatingMultIndep
	Division	decodes.cwms.rating.CwmsRatingSingleIndep
	GroupAdder	decodes.cwms.validation.CwmsScreeningAlgorithm
	Multiplication	decodes.cwms.validation.DatchkScreeningAlgorithm
	ToIrregularUsingPattern	decodes.cwms.algo.ToIrregularUsingPattern
HDB	CallProcAlg	decodes.hdb.algo.CallProcAlg
	DynamicAggregateAlg	decodes.hdb.algo.DynamicAggregateAlg
	EOPInterpAlg	decodes.hdb.algo.EOPInterpAlg
	EquationSolverAlg	decodes.hdb.algo.EquationSolverAlg
	EstGLDAInflow	decodes.hdb.algo.EstGLDAInflow
	FLGUUnreg	decodes.hdb.algo.FLGUUnreg
	FlowToVolumeAlg	decodes.hdb.algo.FlowToVolumeAlg
	GLDAEvap	decodes.hdb.algo.GLDAEvap
	GLDAUnreg	decodes.hdb.algo.GLDAUnreg
	GlenDeltaBSMBAlg	decodes.hdb.algo.GlenDeltaBSMBAlg
	HdbLookupTimeShiftRating	decodes.hdb.algo.HdbLookupTimeShiftRating
	HdbShiftRating	decodes.hdb.algo.HdbShiftRating
	InflowAdvancedAlg	decodes.hdb.algo.InflowAdvancedAlg
	InflowBasicAlg	decodes.hdb.algo.InflowBasicAlg
	MPRCUnreg	decodes.hdb.algo.MPRCUnreg
	NVRNUnreg	decodes.hdb.algo.NVRNUnreg
	ParshallFlume	decodes.hdb.algo.ParshallFlume
	PowerToEnergyAlg	decodes.hdb.algo.PowerToEnergyAlg
	SideInflowAlg	decodes.hdb.algo.SideInflowAlg
	SimpleDisaggAlg	decodes.hdb.algo.SimpleDisaggAlg
	TimeWeightedAverageAlg	decodes.hdb.algo.TimeWeightedAverageAlg
	VolumeToFlowAlg	decodes.hdb.algo.VolumeToFlowAlg

OpenDCS Standard Algorithms

Standard - Arithmetic

In this section a number of the default standard algorithms are presented. These algorithms are grouped together because generally these algorithms are for executing simple arithmetic.

Algorithm	Description
AddToPrevious	Adds the current value to the previous value
AverageAlgorithm	Averages an ‘input’ parameter to an ‘average’ parameter
ChooseOne	Given two inputs, output the best one
CopyAlgorithm	Copies an ‘input’ parameter to an ‘output’ parameter
CopyNoOverwrite	Copies an ‘input’ parameter to an ‘output’ parameter
DisAggregate	Spreads out the input values to outputs in various ways
FillForward	Project an input value by copying it forward in time
Resample	Resample an input to an output with a different interval
RunningAverageAlgorithm	Averages an ‘input’ parameter to an ‘average’ parameter
ScalarAdder	Multiples up to 10 ‘input’ values by coefficients
SubSample	Convert a short interval to a longer interval
SumOverTimeAlgorithm	Sums single ‘input’ parameter to a single ‘sum’ parameter
ToIrregularUsingPattern	Interpolates an ‘input’ to have dates matching Pattern

Recall, that when a computation is set up, the output is a separate time series. Input time series are NOT being manipulated or edited.

AddToPrevious

Exec Class: decodes.tsdb.algo.AddToPrevious

The “Add To Previous” algorithm AddToPrevious adds the previous value to the current value. By default, the following criteria are assumed or executed.

• If the previous time slice is missing, the prior non-missing value will be added to the current value.

• If a current time slice is missing a value, then the corresponding output time slice will also be missing.

See the image above to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	output

AverageAlgorithm

Exec Class: decodes.tsdb.algo.AverageAlgorithm

The “Average” algorithm AverageAlgorithm aggregates and calculates an average over a period defined by the output parameter. By default, the following criteria are assumed or executed.

• Minimum samples needed for algorithm is 1

• Average calculated will include the lower bound

• Average calculated will not include the upper bound

• Average value will be stored at the lower bound time slice, irregardless of upper/lower bounds defined

• If an input is deleted, and as a result the minimum number of samples is no longer met, then the previously calculated output will be deleted.

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	average

ChooseOne

Exec Class: decodes.tsdb.algo.ChooseOne

The “Choose One” algorithm ChooseOne will choose one value (the best one) from two time series to output. Additionally, some upper and lower criteria limits can be applied. By default, the following criteria are assumed or executed.

• If only one value is provided, and it is acceptable, use this value.

• If only one value is provided, and it is not acceptable, use neither.

• If two values are within the acceptable limits, use the higher value.

• If two values are provided but only one is acceptable, use the acceptable value.

• If two values are provided and neither is acceptable, use neither.

• Values higher than the upper limit (but not including), will be considered unacceptable.

• Values lower than the lower limit (but not including), will be considered unacceptable.

In the example above, the limits are set to an upper limit of 176.905 and a lower limit of 176.88. This means that a value of 176.905 will be considered valid, but 176.906 will be invalid. Likewise, a value of 176.88 will be considered valid but anything lower will be considered invalid.

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input1
	input2
Outputs	output

CopyAlgorithm

Exec Class: decodes.tsdb.algo.CopyAlgorithm

The “Copy” algorithm CopyAlgorithm will simply copy the values from one time series to another time series. By default the output will be at the exact same time slice as the input.

• If an input time series is missing and a value exists in the corresponding output time series, then the existing output value will remain (ie NOT be overwritten by a missing value)

• Will copy and save all decimal places (i.e. Decimal places displayed in window below are not representative of what the true output is if more decimal places are present in input)

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	output

CopyNoOverwrite

Exec Class: decodes.tsdb.algo.CopyNoOverwrite

By default the following criteria are met or assumed in the algorithm.

• If the output time series already has a value, it will NOT be overwritten by an input value or missing input (Computation Editor does not show what will be saved).

• The property “input_MISSING” is set to ignore.

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	output

DisAggregate

Exec Class: decodes.tsdb.algo.DisAggregate

The “disaggregate” algorithm or DisAggregate will take an input time series and spread the values to an output time series. This algorithm requires that the interval of the input is equal to or longer than the output. For example, this algorithm is ideal for converting a daily time series to an hourly time series, or a monthly to a daily time series. There are two methods that this algorithm can be invoked. It will either fill the new time series with the input time value, or split the input over x time slices.

By default the following criteria are met or assumed in the algorithm.

• The lower bound of the disaggregated time window is equal to the input time slice.

• By default the property “method” will be set to fill.

• Only two options for computation method: split or fill.

• If an input value is split over x intervals, at least 5 decimal places will save.

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	output

FillForward

Exec Class: decodes.tsdb.algo.FillForward

The “fill forward” algorithm or FillForward will take an input time series slice and apply the value x number of time slices forwards, starting with the current time slice. For example, if the property NumIntervals is set 4 then the values at time slice t will be copied to the same time slice t in the output time series, and then copied to 3 time slices forward in time.

By default the following criteria are met or assumed in the algorithm.

• Default NumIntervals property is set to 4.

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	output

Resample

Exec Class: decodes.tsdb.algo.Resample

The “resample” algorithm or Resample will take an input time series at some resolution and apply it to a higher time resolution. For example, an input may be a daily time series while the output may be hourly. Or an input may be a monthly time series while the output may be daily.

By default the following criteria are met or assumed in the algorithm.

• Properties method options are fill and interp

• Default Method is interp

See the images above and below to better understand how the algorithm behaves.

Role	Role Name
Inputs	input
Outputs	output

RunningAverageAlgorithm

Exec Class: decodes.tsdb.algo.RunningAverageAlgorithm

The “running average” algorithm or RunningAverageAlgorithm will take an input time series at some resolution and calculate an average based on the previous aggregate periodo interval. For example, if the aggregate period interval is one week, then the running average for a daily time series will be calculated based on the previous 6 days and current day.

By default the following criteria are met or assumed in the algorithm.

Role	Role Name
Inputs	input
Outputs	average

See the images above and below to better understand how the algorithm behaves.

ScalarAdder

Exec Class: decodes.tsdb.algo.ScalerAdder

The “scaler adder” algorithm or ScalarAdder will calculate a sum over a specific time slice from multiple time series. There is an option to include multipliers to each time series. There are no restrictions for the multipliers.

Role	Role Name
Inputs	input1
	input2
	input3
	input4
	input5
	input6
	input7
	input8
	input9
	input10
Outputs	output

SubSample

Exec Class: decodes.tsdb.algo.SubSample

The “sub sample” algorithm or SubSample will turn a time series of a high resolution to a lower resolution. For example, an hourly instantaneous time series might be converted into a daily instantaneous time series by sampling the top of day hour. Or a 15-minute time series may be turned into an hourly time series by sampling the top of hour values.

Role	Role Name
Inputs	input
Outputs	output

SumOverTimeAlgorithm

Exec Class: decodes.tsdb.algo.SumOverTimeAlgorithm

The “sum over time” algorithm or SumOverTimeAlgorithm will calculate the sum over a given period of time. For example hourly values can be added up over a day to calculate a daily time series. Or a daily time series can be added up to calculate a weekly or monthly total. By default the aggLowerBoundClosed property is False and the aggUpperBoundClosed property is True. The minSamplesNeeded by default is 1.

Role	Role Name
Inputs	input
Outputs	output

ToIrregularUsingPattern

The ToIrregularusingPattern Algorithm generates a new time series data set from an existing irregular or regular interval time series data set. The times for the new time series are defined by the times of a second time series data set. Values for the new time series are computed from the original time series data by interpolating between the two bounding input point using three methods. The data type of the original time series data governs how values are interpolated.

• Data type “INST-VAL” (or “INST-CUM”) considers the value to change linearly over the interval from the previous data value to the current data value.

• Data type “PER-AVER” considers the value to be constant at the current data value over the interval.

• Data type “PER-CUM” considers the value to increase from 0.0 (at the start of the interval) up to the current value over the interval.

Interpolation of the three data types is illustrated below.

Role	Role Name
Inputs	input
Inputs	pattern
Outputs	output

… more content coming soon …

Standard - Hydrologic

Algorithm	Description
BridgeClearance	Subtract water level from constant ‘low chord’
EstimatedInflow	Estimate inflow based on change in storage and outflow
IncrementalPrecip	Compute incremental precip from cumulative precip
RdbRating	Implements rating table computations - flow vs stage
TabRating	Implements rating table computations - flow vs stage
UsgsEquation	USGS Equation O = A* (B + I)^C + D
VirtualGage	Compute virtual elevation based on two other gages
RelativeHumidity	Compute relative humidity from temperature and dewPoint

BridgeClearance

Exec Class: decodes.tsdb.algo.BridgeClearance

EstimatedInflow

Exec Class: decodes.tsdb.algo.EstimatedInflow

IncrementalPrecip

Exec Class: decodes.tsdb.algo.IncrementalPrecip

RdbRating

Exec Class: decodes.tsdb.algo.RdbRating

… more content coming soon …

TabRating

Exec Class: decodes.tsdb.algo.TabRating

… more content coming soon …

UsgsEquation

Exec Class: decodes.tsdb.algo.UsgsEquation

… more content coming soon …

VirtualGage

Exec Class: decodes.tsdb.algo.VirtualGage

… more content coming soon …

RelativeHumidity

Exec Class: decodes.tsdb.algo.RelativeHumidity

Calculates relative humidity with temperature and dew point data. Air temperature and dew point temperature are assumed to be in °C. Calculates relative humidity RH using the formula, RH = 100 × {exp[17.625 × Dp/(243.04 + Dp)]/exp[17.625 × T/(243.04 + T)]}. dew point temperature can not be above air temperature and output most share same interval as the temperature timeSeries.

By default the following criteria are met or assumed in the algorithm.

Role	Role Name
Inputs	temperature
	dewPoint
Outputs	output

… more content coming soon …

Standard - Arithmetic - Hidden

… more content coming soon …

Standard - Hydrologic Specific - Hidden

… more content coming soon …

CWMS Only - Hydrologic

Algorithm	Description
CwmsRatingMultiIndep	Implements CWMS Rating Computations
CwmsRatingSingleIndep	Implements CWMS Rating Computations
CwmsScreening	CWMS Validation with CWMS Screening Records
DatchkScreening	CWMS Validation with DATCHK files

CwmsRatingMultiIndep

Exec Class: decodes.cwms.rating.CwmsRatingMultIndep

CwmsRatingSingleIndep

Exec Class: decodes.cwms.rating.CwmsRatingSingleIndep

CwmsScreening

Exec Class: decodes.cwms.validation.CwmsScreeningAlgorithm

DatchkScreening

Exec Class: decodes.cwms.validation.DatchkScreeningAlgorithm

HDB Only - Hydrologic

Algorithm	Description
CallProcAlg	decodes.hdb.algo.CallProcAlg
DynamicAggregateAlg	decodes.hdb.algo.DynamicAggregateAlg
EOPInterpAlg	decodes.hdb.algo.EOPInterpAlg
EquationSolverAlg	decodes.hdb.algo.EquationSolverAlg
EstGLDAInflow	decodes.hdb.algo.EstGLDAInflow
FLGUUnreg	decodes.hdb.algo.FLGUUnreg
FlowToVolumeAlg	decodes.hdb.algo.FlowToVolumeAlg
GLDAEvap	decodes.hdb.algo.GLDAEvap
GLDAUnreg	decodes.hdb.algo.GLDAUnreg
GlenDeltaBSMBAlg	decodes.hdb.algo.GlenDeltaBSMBAlg
HdbLookupTimeShiftRating	decodes.hdb.algo.HdbLookupTimeShiftRating
HdbShiftRating	decodes.hdb.algo.HdbShiftRating
InflowAdvancedAlg	decodes.hdb.algo.InflowAdvancedAlg
InflowBasicAlg	decodes.hdb.algo.InflowBasicAlg
MPRCUnreg	decodes.hdb.algo.MPRCUnreg
NVRNUnreg	decodes.hdb.algo.NVRNUnreg
ParshallFlume	decodes.hdb.algo.ParshallFlume
PowerToEnergyAlg	decodes.hdb.algo.PowerToEnergyAlg
SideInflowAlg	decodes.hdb.algo.SideInflowAlg
SimpleDisaggAlg	decodes.hdb.algo.SimpleDisaggAlg
TimeWeightedAverageAlg	decodes.hdb.algo.TimeWeightedAverageAlg
VolumeToFlowAlg	decodes.hdb.algo.VolumeToFlowAlg

OpenDCS Custom Algorithms

In addition to the standard algorithms outlined above, users can set up custom algorithms that can be called upon in calculations. There are two methods for creating custom algorithms: python and java.

Python Algorithms

Exec Class: decodes.tsdb.algo.PythonAlgorithm

Creating a New Python Algorithm <https://opendcs-env.readthedocs.io/en/latest/legacy-cp-userguide.html#creating-a-new-python-algorithm>

Java Algorithms

There are examples in the OpenDCS source code <https://github.com/opendcs/opendcs/tree/master/src/main/java/decodes/tsdb/algo>