# proxi: Proximity Function In ICGE: Estimation of Number of Clusters and Identification of Atypical Units

 proxi R Documentation

## Proximity Function

### Description

Assume that n units are divided into k groups C1,...,Ck. The function calculates the proximity function from a specific unit x0 to the groups Cj.

### Usage

```proxi(d, dx0, pert = "onegroup")
```

### Arguments

 `d` a distance matrix or a `dist` object with distance information between units. `dx0` an n-vector containing the distances from x0 to the other units. `pert` an n-vector that indicates which group each unit belongs to. Note that the expected values of `pert` are numbers greater than or equal to 1 (for instance 1,2,3,4..., k). The default value indicates there is only one group in data.

### Value

k-vector containing the proximity function value from x0 to each group.

### Author(s)

Itziar Irigoien itziar.irigoien@ehu.eus; Konputazio Zientziak eta Adimen Artifiziala, Euskal Herriko Unibertsitatea (UPV/EHU), Donostia, Spain.

Conchita Arenas carenas@ub.edu; Departament d'Estadistica, Universitat de Barcelona, Barcelona, Spain.

### References

Arenas, C. and Cuadras, C.M. (2002). Some recent statistical methods based on distances. Contributions to Science, 2, 183–191.

Cuadras, C.M., Fortiana, J. and Oliva, F. (1997). The proximity of an individual to a population with applications in discriminant analysis. Journal of Classification, 14, 117–136.

`vgeo`, `deltas`

### Examples

```data(iris)
d <- dist(iris[,1:4])

# xo contains a unit from one group, as for example group 1.
x0 <- c(5.3, 3.6, 1.1, 0.1)
# distances between x0 and the other units.
dx0 <- rep(0,150)
for (i in 1:150){
dif <-x0-iris[i,1:4]
dx0[i] <- sqrt(sum(dif*dif))
}

proxi(d, dx0, iris[,5])

# xo contains a unit from one group, as for example group 2.
x0 <- c(6.4, 3.0, 4.8, 1.3)
# distances between x0 and the other units.
dx0 <- rep(0,150)
for (i in 1:150){
dif <-x0-iris[i,1:4]
dx0[i] <- sqrt(sum(dif*dif))
}

proxi(d, dx0, iris[,5])
```

ICGE documentation built on Oct. 17, 2022, 5:10 p.m.