center.fd {fda}

Center Functional Data

Description

Subtract the pointwise mean from each of the functions in a functional data object; that is, to center them on the mean function.

Usage

 center.fd(fdobj)

Arguments

fdobj

a functional data object to be centered.

Value

a functional data object whose mean is zero.

References

Ramsay, James O., Hooker, Giles, and Graves, Spencer (2009), Functional data analysis with R and Matlab, Springer, New York.

Ramsay, James O., and Silverman, Bernard W. (2005), Functional Data Analysis, 2nd ed., Springer, New York.

Ramsay, James O., and Silverman, Bernard W. (2002), Applied Functional Data Analysis, Springer, New York.

See Also

mean.fd, sum.fd, stddev.fd, std.fd

Examples

daytime    <- (1:365)-0.5
daybasis   <- create.fourier.basis(c(0,365), 365)
harmLcoef  <- c(0,(2*pi/365)^2,0)
harmLfd    <- vec2Lfd(harmLcoef, c(0,365))
templambda <- 0.01
dayfd      <- fda::fd(matrix(0, daybasis$nbasis, 1), daybasis)
tempfdPar  <- fda::fdPar(dayfd, harmLfd, templambda)

# do not run on CRAN because it takes too long.
tempfd     <- smooth.basis(daytime,
       CanadianWeather$dailyAv[,,"Temperature.C"], tempfdPar)$fd
tempctrfd  <- center.fd(tempfd)
oldpar <- par(no.readonly= TRUE)
plot(tempctrfd, xlab="Day", ylab="deg. C",
     main = "Centered temperature curves")
par(oldpar)