R: Vector velocity plot.

vector plots {OceanView} | R Documentation

## Vector velocity plot.

### Description

Displays (velocity) vectors as segments.

### Usage

    vectorplot(u, v, x = 0, y = 0, colvar = NULL, ...,
               col = NULL, NAcol = "white", breaks = NULL, colkey = NULL,
               by = 1, arr = FALSE, xfac = NULL,
               clim = NULL, clab = NULL, add = FALSE)

### Arguments

`u` | A vector with quantities (velocities) in x-direction.
`v` | A vector with quantities (velocities) in y-direction. Should have the same length as `u`
`x` | A vector with x-axis values. If `0`, everything will be radiating from the origin. Usually `x` will be equal to `time`.
`y` | The y-axis value. One number, or a vector of length = u.
`colvar` | The variable used for coloring. It need not be present, but if specified, it should be a vector of dimension equal to `c(nrow(u), ncol(v))`. Values of `NULL`, `NA`, or `FALSE` will toggle off coloration according to `colvar`.
`col` | Colors to be used for coloring the arrows as specified by the `colvar` variable. If `col` is `NULL` and `colvar` is specified, then a red-yellow-blue colorscheme (jet.col) will be used. If `col` is `NULL` and `colvar` is not specified, then `col` will be "black".
`NAcol` | Colors to be used for `colvar` values that are `NA`.
`breaks` | a set of finite numeric breakpoints for the colors; must have one more breakpoint than color and be in increasing order. Unsorted vectors will be sorted, with a warning.
`colkey` | A logical, `NULL` (default), or a `list` with parameters for the color key (legend). List parameters should be one of `side, plot, length, width, dist, shift, addlines, col.clab, cex.clab, side.clab, line.clab, adj.clab, font.clab` and the axis parameters `at, labels, tick, line, pos, outer, font, lty, lwd, lwd.ticks, col.box, col.axis, col.ticks, hadj, padj, cex.axis, mgp, tck, tcl, las`. The defaults for the parameters are `side = 4, plot = TRUE, length = 1, width = 1, dist = 0, shift = 0, addlines = FALSE, col.clab = NULL, cex.clab = par("cex.lab"), side.clab = NULL, line.clab = NULL, adj.clab = NULL, font.clab = NULL`) See colkey from package `plot3D`. The default is to draw the color key on side = 4, i.e. in the right margin. If `colkey` = `NULL` then a color key will be added only if `col` is a vector. Setting `colkey = list(plot = FALSE)` will create room for the color key without drawing it. if `colkey = FALSE`, no color key legend will be added.
`clim` | Only if `colvar` is specified, the range of the colors, used for the color key.
`clab` | Only if `colkey` is not `NULL` or `FALSE`, the label to be written on top of the color key. The label will be written at the same level as the main title. To lower it, `clab` can be made a vector, with the first values empty strings.
`by` | Number increment for plotting vectors. Set this to an integer > `1` if the vector density is too high.
`xfac` | Only for `x` not `NULL`, the proportionality factor with which the vectors on the x-axis must be drawn. A value of `1` means that the distance of one will be drawn as one x-unit on the x-axis. For a value of `2` a distance of 1 will appear as 2 x-units on the x-axis. if `NULL`, the range on the y-axis is used. In that case, it may be necessary to manually set the `xlim` of the figure.
`arr` | If `TRUE`, then Arrows will be drawn; if `FALSE`, segments will be drawn.
`add` | If `TRUE`, will add to the current plot.
`...` | additional arguments passed to the plotting methods.

### Value

none

### See Also

quiver2D, flowpath, for other functions to plot velocities.

### Examples

    # save plotting parameters
     mf <- par("mfrow")

    ## =======================================================================
    ##  EXAMPLE 1:
    ## =======================================================================

     par(mfrow = c(2, 2))

     u <- cos(seq(0, 2*pi, 0.1))
     v <- sin(seq(0, 2*pi, 0.1)+ 1)

     vectorplot(u = u, v = v)
     vectorplot(u = u, v = v, col = 1:10)

     x <- seq(0, 1, length.out = length(u))
     vectorplot(u = u, v = v, x = x, xfac = 3)
     points(x, rep(0, length(u)), pch = "+", col = "red")

     vectorplot(u = u, v = v, x = 1:length(u), xfac = 10)

    ## =======================================================================
    ##  EXAMPLE 2:  adding to a plot
    ## =======================================================================

     par(mfrow = c(2, 2))
     x <- 1:length(u)
     plot(x, u)
     vectorplot(u = u, v = v, x = x, xfac = 10,
                add = TRUE, col = "red")

     vectorplot(u = u, v = v, x = x, xfac = 10,
       colvar = sqrt(u^2+v^2), clab = "m/s")

     vectorplot(u = u, v = v, x = x, xfac = 10,
       colvar = sqrt(u^2+v^2), clab = "m/s", log = "c")

    # reset plotting parameters
     par(mfrow = mf)

[Package OceanView version 1.0.6 Index]