velocityStatistics {oce}R Documentation

Report Statistics of adp or adv Velocities

Description

Report statistics of ADP or ADV velocities, such as means and variance ellipses.

Usage

velocityStatistics(x, control, ...)

Arguments

x

an ADV or ADP object.

control

an optional list used to specify more information. In this version, this is ignored for ADV objects. For ADP objects, if control$bin is an integer, it is taken as the bin to be selected (otherwise, an average across bins is used).

...

additional arguments that are used in the call to mean.

Details

This function has been tested on only a single file, and the data-scanning algorithm was based on visual inspection of that file. Whether it will work generally is an open question.

Value

A list containing items the major and minor axes of the covariance ellipse (ellipseMajor and ellipseMinor), the angle of the major axis anticlockwise of the horizontal axis (ellipseAngle), and the x and y components of the mean velocity (uMean and vMean).

Author(s)

Dan Kelley

Examples

library(oce)
data(adp)
a <- velocityStatistics(adp)
print(a)
t <- seq(0, 2*pi, length.out=100)
theta <- a$ellipseAngle * pi / 180
y <- a$ellipseMajor * cos(t) * sin(theta) + a$ellipseMinor * sin(t) * cos(theta)
x <- a$ellipseMajor * cos(t) * cos(theta) - a$ellipseMinor * sin(t) * sin(theta)
plot(adp, which="uv+ellipse+arrow")
lines(x, y, col='blue', lty="dashed", lwd=5)
arrows(0, 0, a$uMean, a$vMean, lwd=5, length=1/10, col='blue', lty="dashed")

[Package oce version 0.9-18 Index]