Extract model matrix from GAM fit

Obtains the model matrix from a fitted gam object.

# S3 method for class 'gam'
model.matrix(object, ...)

Arguments

object

fitted model object of class gam as produced by gam().

...

other arguments, passed to predict.gam.

Details

Calls predict.gam with no newdata argument and type="lpmatrix" in order to obtain the model matrix of object.

Value

A model matrix.

Author

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

References

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

See also

gam

Examples

require(mgcv)
n <- 15
x <- runif(n)
y <- sin(x*2*pi) + rnorm(n)*.2
mod <- gam(y~s(x,bs="cc",k=6),knots=list(x=seq(0,1,length=6)))
model.matrix(mod)
#>    (Intercept)        s(x).1      s(x).2      s(x).3      s(x).4
#> 1            1 -0.0358161296 -0.33951467  0.40292056 -0.20338750
#> 2            1 -0.1511081574  0.02367616  0.37146746 -0.53320915
#> 3            1 -0.0005642836 -0.33414082  0.14450034  0.24976392
#> 4            1 -0.2073061920  0.51270884  0.07937145 -0.45410792
#> 5            1  0.7249323915  0.45481408 -0.14502251  0.04368054
#> 6            1  0.0336404468  0.90061386 -0.25533091 -0.14142693
#> 7            1 -0.0447503891 -0.32536544  0.42443596 -0.26136803
#> 8            1 -0.1970396830 -0.29531387 -0.78682890 -0.45932791
#> 9            1 -0.0064550624 -0.35181695  0.24410579  0.10263867
#> 10           1 -0.0111464836 -0.25727535 -0.14017063  0.55758337
#> 11           1 -0.0253097872 -0.22643407 -0.24895348  0.62951795
#> 12           1 -0.1110647308 -0.14194338  0.43851807 -0.49126124
#> 13           1  0.0570589268  0.89770798 -0.25860284 -0.12884496
#> 14           1 -0.0036005108 -0.28432113 -0.04662778  0.47420937
#> 15           1 -0.0214703556 -0.23339524 -0.22378257  0.61553983
#> attr(,"model.offset")
#> [1] 0