R: PointsUpdate

PointsUpdate {adlift} | R Documentation

## PointsUpdate

### Description

This function performs the update lifting step using a given configuration of neighbours and boundary handling.

### Usage

    PointsUpdate(X, coeff, nbrs, index, remove, pointsin, weights, lengths)

### Arguments

`X` | the vector of grid values.
`coeff` | the vector of detail and scaling coefficients at that step of the transform.
`nbrs` | the indices (into X) of the neighbours to be used in the lifting step.
`index` | the indices into pointsin of nbrs, the neighbours of remove.
`remove` | the index (into X) of the point to be removed.
`pointsin` | The indices of gridpoints still to be removed.
`weights` | the prediction weights obtained from the regression in the prediction step of the transform.
`lengths` | the vector of interval lengths at the present step of the transform (to be updated).

### Details

The procedure performs a minimum norm update lifting step. Firstly the interval lengths are updated using the coefficients obtained. Secondly, the scaling and detail coefficient vector is modified using the new interval lengths.

### Value

`coeff` | vector of (modified) detail and scaling coefficients to be used in the next step of the transform.
`lengths` | the vector of interval lengths after the update step of the transform.
`r` | the index into pointsin of remove.
`N` | length(pointsin).
`weights` | The regression coefficients used in prediction.
`alpha` | the update weights used to update lengths and coeff.

### Author(s)

Matt Nunes (nunesrpackages@gmail.com), Marina Knight

### See Also

`AdaptNeigh`, `AdaptPred`, `CubicPred`, `fwtnp`, `LinearPred`, `QuadPred`, `UndoPointsUpdate`

### Examples

    #
    # Generate some blocks data: 100 observations.
    #
    x <- runif(100)
    y <-make.signal2("blocks",x=x)
    #
    #find initial interval lengths...
    #
    I<-intervals(x,"reflect")
    lengths<-lengthintervals(x,I,neighbours=2,closest=FALSE)
    #
    #perform prediction step...
    p<-AdaptNeigh(order(x),x,y,32,5,TRUE,2)
    #
    #
    u<-PointsUpdate(x,p$results[[6]],p$newinfo[[2]],p$newinfo[[3]],5,order(x),p$results[[4]],lengths)
    #
    #and here are the updated coefficients...
    u$coeff
    #

[Package adlift version 1.4-1 Index]