public class LinearInterpolator extends Plottable
Class used to interpolate datasource values from the collection of (timestamp, values) points. This class is suitable for linear interpolation only.
Interpolation algorithm returns different values based on the value passed to
setInterpolationMethod()
. If not set, interpolation
method defaults to standard linear interpolation (LinearInterpolator.Method.LINEAR
).
Interpolation method handles NaN datasource
values gracefully.
Modifier and Type | Class and Description |
---|---|
static class |
LinearInterpolator.Method
A enumeration of interpolation methods
|
Modifier and Type | Field and Description |
---|---|
(package private) double |
b0 |
(package private) double |
b1 |
static int |
INTERPOLATE_LEFT
constant used to specify LEFT interpolation.
|
static int |
INTERPOLATE_LINEAR
constant used to specify LINEAR interpolation (default interpolation method).
|
static int |
INTERPOLATE_REGRESSION
constant used to specify LINEAR REGRESSION as interpolation method.
|
static int |
INTERPOLATE_RIGHT
constant used to specify RIGHT interpolation.
|
Constructor and Description |
---|
LinearInterpolator(Calendar[] dates,
double[] values)
Creates LinearInterpolator from arrays of timestamps and corresponding datasource values.
|
LinearInterpolator(Date[] dates,
double[] values)
Creates LinearInterpolator from arrays of timestamps and corresponding datasource values.
|
LinearInterpolator(long[] timestamps,
double[] values)
Creates LinearInterpolator from arrays of timestamps and corresponding datasource values.
|
Modifier and Type | Method and Description |
---|---|
double |
getValue(long timestamp)
Retrieves datapoint value based on a given timestamp.
|
void |
setInterpolationMethod(int interpolationMethod)
Deprecated.
uses
setInterpolationMethod(Method) instead. |
void |
setInterpolationMethod(LinearInterpolator.Method interpolationMethod)
Sets interpolation method to be used.
|
public static final int INTERPOLATE_LEFT
setInterpolationMethod()
for explanation.public static final int INTERPOLATE_RIGHT
setInterpolationMethod()
for explanation.public static final int INTERPOLATE_LINEAR
setInterpolationMethod()
for explanation.public static final int INTERPOLATE_REGRESSION
setInterpolationMethod()
for explanation.double b0
double b1
public LinearInterpolator(long[] timestamps, double[] values)
timestamps
- timestamps in secondsvalues
- corresponding datasource valuesIllegalArgumentException
- Thrown if supplied arrays do not contain at least two values, or if
timestamps are not ordered, or array lengths are not equal.public LinearInterpolator(Date[] dates, double[] values)
dates
- Array of Date objectsvalues
- corresponding datasource valuesIllegalArgumentException
- Thrown if supplied arrays do not contain at least two values, or if
timestamps are not ordered, or array lengths are not equal.public LinearInterpolator(Calendar[] dates, double[] values)
dates
- array of GregorianCalendar objectsvalues
- corresponding datasource valuesIllegalArgumentException
- Thrown if supplied arrays do not contain at least two values, or if
timestamps are not ordered, or array lengths are not equal.@Deprecated public void setInterpolationMethod(int interpolationMethod)
setInterpolationMethod(Method)
instead.Sets interpolation method to be used. Suppose that we have two timestamp/value pairs:
(t, 100)
and (t + 100, 300)
. Here are the results interpolator
returns for t + 50 seconds, for various interpolationMethods
:
INTERPOLATE_LEFT: 100
INTERPOLATE_RIGHT: 300
INTERPOLATE_LINEAR: 200
If not set, interpolation method defaults to INTERPOLATE_LINEAR
.
The fourth available interpolation method is INTERPOLATE_REGRESSION. This method uses simple linear regression to interpolate supplied data with a simple straight line which does not necessarily pass through all data points. The slope of the best-fit line will be chosen so that the total square distance of real data points from from the best-fit line is at minimum.
This method is deprecated, one should use setInterpolationMethod()
instead.
The full explanation of this interpolation method can be found here.
interpolationMethod
- Should be INTERPOLATE_LEFT
,
INTERPOLATE_RIGHT
, INTERPOLATE_LINEAR
or
INTERPOLATE_REGRESSION
. Any other value will be interpreted as
INTERPOLATE_LINEAR (default).public void setInterpolationMethod(LinearInterpolator.Method interpolationMethod)
Sets interpolation method to be used. Suppose that we have two timestamp/value pairs:
(t, 100)
and (t + 100, 300)
. Here are the results interpolator
returns for t + 50 seconds, for various interpolationMethods
:
LEFT: 100
RIGHT: 300
LINEAR: 200
If not set, interpolation method defaults to INTERPOLATE_LINEAR
.
The fourth available interpolation method is REGRESSION. This method uses simple linear regression to interpolate supplied data with a simple straight line which does not necessarily pass through all data points. The slope of the best-fit line will be chosen so that the total square distance of real data points from from the best-fit line is at minimum.
The full explanation of this interpolation method can be found here.
interpolationMethod
- a method from LinearInterpolator.Method
.public double getValue(long timestamp)