drawDirectionField {oce}R Documentation

Draw a direction field

Description

Draw a direction field

Usage

drawDirectionField(x, y, u, v, scalex, scaley, add=FALSE, type=1,
debug=getOption("oceDebug"), ...)

Arguments

x,y

coordinates at which velocities are specified

u,v

velocity components in the x and y directions

scalex,scaley

scale to be used for the velocity arrows. Exactly one of these must be specified. Arrows that have u^2+v^2=1 will have length scalex along the x axis, or scaley along the y axis, according to which argument is given.

add

if TRUE, the arrows are added to an existing plot; otherwise, a new plot is started, with asp set to 1.

type

type of the arrow-like indication of the direction.

debug

debugging value; set to a positive integer to get debugging information.

...

extra graphical parameters, supplied to functions called by drawDirectionField. Try adjusting cex, pch, and lwd, and col.

Details

The direction field is indicated variously, depending on the value of type.

For type=1, each indicator is drawn with a symbol, according to the value of pch (either supplied globally, or as an element of the ... list) and of size cex, and colour col. Then, a line segment is drawn for each, and for this lwd and col may be set globally or in the ... list.

For type=2, the points are not drawn, but arrows are drawn instead of the line segments. Again, lwd and col control the type of the line.

Value

None.

Author(s)

Dan Kelley

Examples

library(oce)
plot(c(-1.5, 1.5), c(-1.5, 1.5), xlab="", ylab="", type='n')
drawDirectionField(x=rep(0, 2), y=rep(0, 2), u=c(1,1), v=c(1, -1), scalex=0.5, add=TRUE)
plot(c(-1.5, 1.5), c(-1.5, 1.5), xlab="", ylab="", type='n')
drawDirectionField(x=rep(0, 2), y=rep(0, 2), u=c(1,1), v=c(1, -1), scalex=0.5, add=TRUE,
                   type=2)
plot(c(-1.5, 1.5), c(-1.5, 1.5), xlab="", ylab="", type='n')
drawDirectionField(x=rep(0, 2), y=rep(0, 2), u=c(1,1), v=c(1, -1), scalex=0.5, add=TRUE,
                   type=2, length=0.1)

[Package oce version 0.9-18 Index]