fda.usc (version 0.9.4)

fdata.deriv: Computes the derivative of functional data object.

Description

Computes the derivative of functional data.

Usage

fdata.deriv(fdataobj,nderiv=1,method="bspline",class.out='fdata'
,nbasis=NULL,...)

Arguments

fdataobj

fdata class object.

nderiv

Order of derivation, by defalult nderiv=1.

method

Type of derivative method, for more information see details.

class.out

Class of functional data returned: fdata or fd class.

nbasis

Number of Basis for fdatataobj$DATA. It is only used if method ="bspline", "exponential", "fourier", "monomial" or "polynomial"

...

Further arguments passed to or from other methods.

Value

• Returns the derivative of functional data of fd class if class.out="fd" or fdata class if class.out="fdata".

Details

If method ="bspline", "exponential", "fourier", "monomial" or "polynomial" fdata.deriv function creates a basis to represent the functional data. The functional data are converted to class fd using the Data2fd function and the basis indicated in the method. Finally, the function calculates the derivative of order nderiv of curves using deriv.fd function. If method="fmm", "periodic", "natural" or "monoH.FC" is used splinefun function. If method="diff", raw derivation is applied. Not recommended to use this method when the values are not equally spaced.

See Also

See also deriv.fd, splinefun and fdata

Examples

data(tecator)
absorp=tecator$absorp.fdata
tecator.fd1=fdata2fd(absorp)
tecator.fd2=fdata2fd(absorp,"fourier",9)
tecator.fd3=fdata2fd(absorp,"fourier",nbasis=9,nderiv=1)
#tecator.fd1;tecator.fd2;tecator.fd3
tecator.fdata1=fdata(tecator.fd1)
tecator.fdata2=fdata(tecator.fd2)
tecator.fdata3=fdata(tecator.fd3)
tecator.fdata4=fdata.deriv(absorp,nderiv=1,method="bspline",
class.out='fdata',nbasis=9)
tecator.fd4=fdata.deriv(tecator.fd3,nderiv=0,class.out='fd',nbasis=9)
#plot(tecator.fdata4)


basi=c("bspline", "exponential", "fourier","monomial","polynomial")
#no run  with "constant","polygonal","power" basis
fdata.deriv(absorp,nderiv=1,method=basi[3],class.out='fd',nbasis=11) #