sl.mhd: Modified Hausdorff Distance (MHD) Calculator

Description Usage Arguments Details Value Author(s) See Also Examples

View source: R/sl.mhd.R

Description

This function calculates the Modified Hausdorff Distance between two sea ice edges

Usage

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sl.mhd(A,B,cA=NULL,cB=NULL,kA=NULL,kB=NULL,R=1)

Arguments

A

A m x 2 array, containing the (lon,lat) coordinates of the m points forming the (first) edge.

B

A n x 2 array, containing the (lon,lat) coordinates of the n points forming the (second) edge.

cA

A p x 2 optional array, containing the (lon,lat) coordinates of the p points of the (first) land-ice interface between ice and land.

cB

A q x 2 optional array, containing the (lon,lat) coordinates of the q points of the (second) land-ice interface between ice and land.

kA

An optional integer that can vary between 1 and the number of points of the segment A (1<kA<m). This represents the frequency with which the points in A are considered by the algorithm. As example, if kA=2, every second point is taken into account for the computation of the MHD, neglecting half of them. This parameter can be useful to speed up the computations, expecially when segment A has a shorter spatial step compared to B. However it can affect the accuracy of the calculated MHD, so be careful when using it. DEFAULT -> kA = 1

kB

An optional integer that can vary between 1 and the number of points of the segment B (1<kA<n). This represents the frequency with which the points in B are considered by the algorithm. As example, if kB=2, every second point is taken into account for the computation of the MHD, neglecting half of them. This parameter can be useful to speed up the computations, expecially when segment B has a shorter spatial step compared to A. However it can affect the accuracy of the calculated MHD, so be careful when using it. DEFAULT -> kB = 1

R

Radius of the sphere. DEFAULT -> R = 1. If R = -1, then R = 6373044 [m], which is the mean quadratic radius.

Details

To calculate the coordinates of the edge and of the land-ice interface please refer to the function sl.mhd.edge. sl.mhd.edge output is the natural imput for sl.mhd. The distance employed to compute the MHD is the "great circle distance", given by sl.gc.dist.

Value

The MHD value in meters.

Author(s)

Lorenzo Zampieri

See Also

sl.mhd.edge

Examples

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MHD <- sl.mhd(Edge1,Edge2,LandEdge1,LandEdge2,R=-1)
## sl.mhd(Edge1,Edge2,LandEdge1,LandEdge2) 
## Should result in double, which represent the MHD of the two edges in meters

helgegoessling/spheRlab documentation built on Sept. 29, 2017, 6:36 a.m.