addArrowMark {trackViewer} | R Documentation

## Add arrow mark to the figure at a given position

### Description

A function to add arrow mark for emphasizing peaks

### Usage

    addArrowMark(pos=grid.locator(), label=NULL, angle=15,
                 length=unit(.25, "inches"), col="red", cex=1, quadrant=4,
                 type="closed", vp=NULL)

### Arguments

`pos` | A unit object representing the location of arrow mark to be placed at current viewport. Default is the value of grid.locator, which will get the location of the mouse click.
`label` | A character or expression vector.
`angle` | A parameter passed into grid::arrow function. The angle of arrow head in degrees (smaller numbers produce narrower, pointier arrows). Essentially describes the width of the arrow head.
`length` | A parameter passed into grid::arrow function. Aunit specifying the length of the arrow head.
`col` | color of the arrow
`cex` | Multiplier applied to fontsize
`quadrant` | the direction of arrow, 1: to bottomleft, 2: to bottomright, 3: to topright, 4: to topleft
`type` | A parameter passed into grid::arrow function. One of "open" or "closed" indicating whether the arrow head should be a closed triangle.
`vp` | A Grid viewport object. It must be output of `viewTracks`

### Value

invisible x, y position value.

### Author(s)

Jianhong Ou

### See Also

See Also as `addGuideLine`, `arrow`

### Examples

        grid.newpage()
        addArrowMark(list(x=unit(.5, "npc"),
                          y=unit(.5, "npc")),
                     label="label1",
                     col="blue")
        ## how to get the position by mouse click
        if(interactive()){
            pos <- addArrowMark(label="byClick")
            addArrowMark(pos, label="samePosAsAbove")
        }

[Package trackViewer version 1.14.1 Index]