R: Convert Smoothing Parameter to Degrees of Freedom

lambda2df {fda} | R Documentation

## Convert Smoothing Parameter to Degrees of Freedom

### Description

The degree of roughness of an estimated function is controlled by a smoothing parameter $lambda$ that directly multiplies the penalty. However, it can be difficult to interpret or choose this value, and it is often easier to determine the roughness by choosing a value that is equivalent of the degrees of freedom used by the smoothing procedure. This function converts a multipler $lambda$ into a degrees of freedom value.

### Usage

    lambda2df(argvals, basisobj, wtvec=rep(1, n),
              Lfdobj=NULL, lambda=0, returnMatrix=FALSE)

### Arguments

`argvals` | a vector containing the argument values used in the smooth of the data.
`basisobj` | the basis object used in the smoothing of the data.
`wtvec` | the weight vector, if any, that was used in the smoothing of the data.
`Lfdobj` | the linear differential operator object used to defining the roughness penalty employed in smoothing the data.
`lambda` | the smoothing parameter to be converted.
`returnMatrix` | logical: If TRUE, a two-dimensional is returned using a special class from the Matrix package.

### Value

the equivalent degrees of freedom value.

### See Also

`df2lambda`

[Package fda version 2.4.8 Index]