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(0.25, "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.

### 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 1.28.1 Index]