coef.boss {BOSSreg} R Documentation

## Select coefficient vector(s) for BOSS.

### Description

This function returns the optimal coefficient vector of BOSS selected by AICc (by default) or other types of information criterion.

### Usage

```## S3 method for class 'boss'
coef(
object,
ic = c("aicc", "bicc", "aic", "bic", "gcv", "cp"),
select.boss = NULL,
...
)
```

### Arguments

 `object` The boss object, returned from calling the `boss` function. `ic` Which information criterion is used to select the optimal coefficient vector for BOSS. The default is AICc-hdf. `select.boss` The index (or indicies) of columns in the coefficient matrix for which one wants to select. By default (NULL) it's selected by the information criterion specified in 'ic'. `...` Extra arguments (unused for now)

### Details

If `select.boss` is specified, the function returns corresponding column(s) in the coefficient matrix.

If `select.boss` is unspecified, the function returns the optimal coefficient vector selected by AICc-hdf (other choice of IC can be specified in the argument `ic`).

### Value

The chosen coefficient vector(s) for BOSS.

### Examples

```## Generate a trivial dataset, X has mean 0 and norm 1, y has mean 0
set.seed(11)
n = 20
p = 5
x = matrix(rnorm(n*p), nrow=n, ncol=p)
x = scale(x, center = colMeans(x))
x = scale(x, scale = sqrt(colSums(x^2)))
beta = c(1, 1, 0, 0, 0)
y = x%*%beta + scale(rnorm(n, sd=0.01), center = TRUE, scale = FALSE)

## Fit the model
boss_result = boss(x, y)

## Get the coefficient vector selected by AICc-hdf (S3 method for boss)
beta_boss_aicc = coef(boss_result)
# the above is equivalent to the following
beta_boss_aicc = boss_result\$beta_boss[, which.min(boss_result\$IC_boss\$aicc), drop=FALSE]
## Get the fitted values of BOSS-AICc-hdf (S3 method for boss)
mu_boss_aicc = predict(boss_result, newx=x)
# the above is equivalent to the following
mu_boss_aicc = cbind(1,x) %*% beta_boss_aicc

## Repeat the above process, but using Cp-hdf instead of AICc-hdf
## coefficient vector
beta_boss_cp = coef(boss_result, method.boss='cp')
beta_boss_cp = boss_result\$beta_boss[, which.min(boss_result\$IC_boss\$cp), drop=FALSE]
## fitted values of BOSS-Cp-hdf
mu_boss_cp = predict(boss_result, newx=x, method.boss='cp')
mu_boss_cp = cbind(1,x) %*% beta_boss_cp
```

[Package BOSSreg version 0.2.0 Index]