org.rrd4j.data

Class Variable

java.lang.Object

org.rrd4j.data.Variable

Direct Known Subclasses:

Variable.AVERAGE, Variable.FIRST, Variable.LAST, Variable.LSLCORREL, Variable.LSLINT, Variable.LSLSLOPE, Variable.MAX, Variable.MIN, Variable.PERCENTILE, Variable.STDDEV, Variable.TOTAL

public abstract class Variable
extends Object

Abstract class for extracting single values from data sets (VDEF in rrdtool).
Provides statistical calculations on RRD values and supports custom computation methods for advanced data processing.

Can be used to add new statistical calculations with RRD values.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Variable.AVERAGE Calculate the average of the data points.
(package private) static class	Variable.ComparPercentElemen The sort used by rrdtool for percent, where NaN < -INF < finite values < INF
static class	Variable.FIRST Find the first valid data point and it's timestamp
static class	Variable.LAST Find the first last valid point and it's timestamp
static class	Variable.LSLCORREL Calculate the correlation coefficient of the least squares line.
static class	Variable.LSLINT Calculate the y-intercept of the least squares line.
static class	Variable.LSLSLOPE Calculate the slop of the least squares line.
static class	Variable.MAX The biggest of the data points and it's time stamp (the first one) is stored.
static class	Variable.MIN The smallest of the data points and it's time stamp (the first one) is stored.
(package private) static class	Variable.PercentElem Store all the informations about a datasource point, for predictive and consistent sorting
static class	Variable.PERCENTILE Find the point at the n-th percentile.
static class	Variable.PERCENTILENAN
static class	Variable.STDDEV Calculate the standard deviation for the data point.
static class	Variable.TOTAL Calculate the sum of the data points.
static class	Variable.Value This class store both the value and the time stamp It will be used by graph rendering legend

Field Summary

Fields

Modifier and Type	Field and Description
static Variable.Value	INVALIDVALUE Represents an invalid value with NaN (Not a Number) value.

Constructor Summary

Constructors

Constructor and Description
Variable()

Method Summary

Modifier and Type	Method and Description
(package private) void	calculate(Source s, long start, long end) Used to calculate the needed value from a source, this method call the abstract method fill(long[], double[], long, long).
protected abstract Variable.Value	fill(long[] timestamps, double[] values, long start, long end) This method is call with the needed values, extracted from the datasource to do the calculation.
Variable.Value	getValue()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

INVALIDVALUE

public static final Variable.Value INVALIDVALUE

Represents an invalid value with NaN (Not a Number) value.

Constructor Detail

Variable

public Variable()

Method Detail

calculate

void calculate(Source s,
               long start,
               long end)

Used to calculate the needed value from a source, this method call the abstract method fill(long[], double[], long, long).

Parameters:

s -

start -

end -

fill

protected abstract Variable.Value fill(long[] timestamps,
                                       double[] values,
                                       long start,
                                       long end)

This method is call with the needed values, extracted from the datasource to do the calculation.

Value is to be filled with both the double value and a possible timestamp, when it's used to find a specific point

Parameters:

timestamps - the timestamps for the value

values - the actual values

start - the start of the period

end - the end of the period

Returns:

a filled Value object

getValue

public Variable.Value getValue()