Predict.matrix             package:mgcv             R Documentation

Prediction methods for smooth terms in a GAM

Description:

     Takes 'smooth' objects produced by 'smooth.construct' methods and
     obtains the matrix mapping  the parameters associated with such a
     smooth to the predicted values of the smooth at a set of new
     covariate values.

     In practice this method is often called via the wrapper function
     'PredictMat'.

Usage:

     Predict.matrix(object,data)
     Predict.matrix2(object,data)

Arguments:

  object: is a smooth object produced by a 'smooth.construct' method
          function. The object  contains all the information required
          to specify the basis for a term of its class, and this
          information is used by the appropriate 'Predict.matrix'
          function to produce a prediction matrix for new covariate
          values. Further details are given in 'smooth.construct'.

    data: A data frame containing the values of the (named) covariates
          at which the smooth term is to be  evaluated. Exact
          requirements are as for 'smooth.construct' and
          'smooth.construct2'

     .

Details:

     Smooth terms in a GAM formula are turned into smooth specification
     objects of  class 'xx.smooth.spec' during processing of the
     formula. Each of these objects is converted to a smooth object
     using an appropriate 'smooth.construct' function. The
     'Predict.matrix'  functions are used to obtain the matrix that
     will map the parameters associated with a smooth term to the
     predicted values for the term at new covariate values.

     Note that new smooth classes can be added by writing a new
     'smooth.construct' method function and a  corresponding
     'Predict.matrix' method function: see the example code provided
     for  'smooth.construct' for details.

Value:

     A matrix which will map the parameters associated with the smooth
     to the vector of values of the smooth  evaluated at the covariate
     values given in 'object'. If the smooth class is one which
     generates offsets the corresponding offset is returned as
     attribute '"offset"' of the matrix.

Author(s):

     Simon N. Wood simon.wood@r-project.org

References:

     Wood S.N. (2006) Generalized Additive Models: An Introduction with
     R. Chapman and Hall/CRC Press.

See Also:

     'gam','gamm', 'smooth.construct', 'PredictMat'

Examples:

     # See smooth.construct examples

