net.talvi.puffinplot.data

Class GreatCircles

java.lang.Object

net.talvi.puffinplot.data.GreatCircles

All Implemented Interfaces:

FisherParams

public final class GreatCircles
extends java.lang.Object
implements FisherParams

This class represents a set of great circles and a set of directions. It calculates a best-fitting mean direction from these data using the method of McFadden and McElhinny (1988).

References:

McFadden, P. L. & McElhinny, M. W., 1988. The combined analysis of remagnetization circles and direct observations in palaeomagnetism. Earth and Planetary Science Letters, 87, pp. 161–172.

Method Summary

Modifier and Type	Method and Description
double	getA95() Returns the alpha-95 value denoting the 95% confidence interval.
java.util.List<GreatCircle>	getCircles() Returns the great circles which were originally supplied to the constructor.
static java.util.List<java.lang.String>	getEmptyFields() Returns a list of empty strings equal in length to the number of parameters.
static java.util.List<java.lang.String>	getHeaders() Returns the headers describing the parameters as a list of strings.
double	getK() Returns the k-value, an estimate of the precision parameter κ.
int	getM() Returns the number of stable endpoints used in the calculation.
Vec3	getMeanDirection() Returns the best-fit mean direction for the supplied circles and directions.
int	getN() Returns the number of great circles used in the calculation.
double	getR() Returns R, the total unit vector path length.
static GreatCircles	instance(java.util.List<Vec3> endpoints, java.util.List<GreatCircle> circles, java.lang.String validityCondition) Calculates a mean direction from the supplied great circle and directions.
boolean	isValid() Returns true if this great-circle fit is valid according to the condition specified in the preferences.
java.util.List<java.lang.String>	toStrings() Returns the statistical parameters as a list of strings.

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.talvi.puffinplot.data.FisherParams

isA95Valid

Method Detail

instance

public static GreatCircles instance(java.util.List<Vec3> endpoints,
                                    java.util.List<GreatCircle> circles,
                                    java.lang.String validityCondition)

Calculates a mean direction from the supplied great circle and directions. At least one endpoint OR at least two great circles are required. This method takes a validity expression written in JavaScript, which is used to determine whether the results of the calculation are considered valid. The expression should return a boolean value. The following variables are available to the expression:

M

the number of endpoints

N

the number of great circles

k

the precision parameter

a95

the α₉₅ value

An unparseable expression will be evaluated to false.

Parameters:

endpoints - a set of directions (probably from linear PCA fits)

circles - a set of great circles

validityCondition - an JavaScript expression to evaluate whether the calculated direction should be considered valid

Returns:

the net.talvi.puffinplot.data.GreatCircles

getM

public int getM()

Returns the number of stable endpoints used in the calculation.

Returns:

the number of stable endpoints used in the calculation

getN

public int getN()

Returns the number of great circles used in the calculation.

Specified by:

getN in interface FisherParams

Returns:

the number of great circles used in the calculation

getCircles

public final java.util.List<GreatCircle> getCircles()

Returns the great circles which were originally supplied to the constructor.

Returns:

the great circles which were originally supplied to the constructor

getMeanDirection

public Vec3 getMeanDirection()

Returns the best-fit mean direction for the supplied circles and directions.

Specified by:

getMeanDirection in interface FisherParams

Returns:

the best-fit mean direction for the supplied circles and directions

toStrings

public java.util.List<java.lang.String> toStrings()

Returns the statistical parameters as a list of strings. The order of the parameters is the same as the order of the headers provided by getHeaders().

Returns:

the statistical parameters as a list of strings

getEmptyFields

public static java.util.List<java.lang.String> getEmptyFields()

Returns a list of empty strings equal in length to the number of parameters.

Returns:

a list of empty strings equal in length to the number of parameters

getHeaders

public static java.util.List<java.lang.String> getHeaders()

Returns the headers describing the parameters as a list of strings.

Returns:

the headers describing the parameters

isValid

public boolean isValid()

Returns true if this great-circle fit is valid according to the condition specified in the preferences.

Returns:

true if this great-circle fit is valid

getA95

public double getA95()

Description copied from interface: FisherParams

Returns the alpha-95 value denoting the 95% confidence interval. The returned value is in degrees.

Specified by:

getA95 in interface FisherParams

Returns:

the alpha-95 value denoting the 95% confidence interval

getK

public double getK()

Description copied from interface: FisherParams

Returns the k-value, an estimate of the precision parameter κ.

Specified by:

getK in interface FisherParams

Returns:

the k-value, an estimate of the precision parameter κ

getR

public double getR()

Description copied from interface: FisherParams

Returns R, the total unit vector path length. For standard Fisher (1953) statistics, R is the length of the sum of the unit vectors corresponding to the directions being analysed. For McFadden & McElhinny (1988) statistics, R has a similar interpretation; see the paper for details.

Specified by:

getR in interface FisherParams

Returns:

R, the total unit vector path length.