velocityStatistics {oce} | R Documentation |
Report statistics of ADP or ADV velocities, such as means and variance ellipses.
velocityStatistics(x, control, ...)
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
|
... |
additional arguments that are used in the call to
|
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.
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
).
Dan Kelley
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")