# Distance-Distance Plot

### Description

`"myplotDD"`

is a revised version of `".myddplot"`

in `"plot-utils.R"`

in the package `"rrcov"`

. In `"myplotDD"`

, `id.n`

and `ind`

are printed out.

### Usage

1 | ```
myplotDD(x, cutoff, id.n)
``` |

### Arguments

`x` |
An S4 object of class |

`cutoff` |
The |

`id.n` |
Number of observations to identify by a label. If not supplied, the number of observations with robust distance larger than |

### Details

Distance-Distance Plot: Plot the vector `y=rd`

(robust distances) against `x=md`

(mahalanobis distances). Identify by a label the `id.n`

observations with largest `rd`

. If `id.n`

is not supplied, calculate it as the number of observations larger than `cutoff`

. Use `cutoff`

to draw a horisontal and a vertical line. Draw also a dotted line with a slope 1.

`"myplotDD(x)"`

is equivalent to `"plot(x, which="dd")"`

.
`which`

: indicate what kind of plot. If `which = "dd"`

, then a distance-distance Plot.

### Value

A distance-distance plot is shown. Return a list with components:

`cutoff ` |
The |

`id.n ` |
Number of observations to identify by a label. If not supplied, the number of observations with robust distance larger than |

`sort.y ` |
A list containing the sorted values of y (the robust distance) |

`ind ` |
The indices of the largest |

### Author(s)

Ying-Ying Zhang (Robert) robertzhangyying@qq.com

### References

Zhang, Y. Y. (2013), An Object Oriented Solution for Robust Factor Analysis.

### See Also

`plot`

, `qchisq`

, `CovClassic`

, `getDistance`

### Examples

1 2 3 4 5 6 7 8 9 10 | ```
data(stock611)
covMcd=CovRobust(x=scale(stock611[,3:12]), control="mcd"); covMcd
## "myplotDD" shows id.n and ind.
## Note: id.n and ind change each time due to covMcd changes each time!
## However, the ind of largest robust distances do not change.
result = myplotDD(x=covMcd); result
## "myplotDD" is equivalent to "plot(x=covMcd, which="dd")".
plot(x=covMcd, which="dd")
``` |