Nothing
### This function is a component of astrochron: An R Package for Astrochronology
### Copyright (C) 2016 Stephen R. Meyers
###
###########################################################################
### dpssTaper: apply a single Discrete Prolate Spheroidal Sequence taper
### to data - (SRM: July 30, 2013; August 3, 2013; August 13, 2013
### Sept. 10, 2015; July 22, 2016)
###
###########################################################################
dpssTaper <- function (dat=NULL,tbw=1,num=1,rms=T,demean=T,detrend=F,genplot=T,verbose=T)
{
if (verbose) cat("\n----- APPLYING DPSS TAPER TO STRATIGRAPHIC SERIES -----\n")
if(!is.null(dat)) dat <- data.frame(dat)
# generate series to evalute spectral properties of window
if(is.null(dat))
{
dat=data.frame( cbind(1:256,rep(1,256)) )
demean=F
detrend=F
genplot=F
}
ipts <- length(dat[,1])
if (verbose) cat(" * Number of data points=", ipts,"\n")
# error checking
dtest <- dat[2:ipts,1]-dat[1:(ipts-1),1]
epsm=1e-9
if( (max(dtest)-min(dtest)) > epsm )
{
cat("\n**** ERROR: sampling interval is not uniform.\n")
stop("**** TERMINATING NOW!")
}
### plots
if(genplot)
{
par(mfrow=c(2,2))
plot(dat,cex=0.5,xlab="Location",ylab="Value",main="Data Series"); lines(dat)
}
###########################################################################
### remove mean and linear trend
###########################################################################
dave <- colMeans(dat[2])
if (demean)
{
dat[2] <- dat[2] - dave
if(verbose) { cat(" * Mean value removed=",dave,"\n") }
}
### use least-squares fit to remove linear trend
if (detrend)
{
lm.0 <- lm(dat[,2] ~ dat[,1])
dat[2] <- dat[2] - (lm.0$coeff[2]*dat[1] + lm.0$coeff[1])
if(verbose) {cat(" * Linear trend removed. m=",lm.0$coeff[2],"b=",lm.0$coeff[1],"\n") }
}
# Calculate DPSS with library multitaper
tapers=dpss(n=ipts,k=num,nw=tbw, returnEigenvalues=FALSE)
# isolate taper of interest
tap = tapers$v[,num]
# normalize taper to RMS=1 to preserve power for white process
if(rms)
{
norm = sqrt( sum(tap*tap)/ipts )
tap = tap/norm
}
# now multiply taper and data
dat[2] <- dat[2] * tap
# multiply taper by maximum data value for plotting
tt <- cbind(dat[1],(tap/max(tap))*max(dat[2]))
if(genplot)
{
### more plots
plot(dat,cex=0.5,xlab="Location",ylab="Tapered Value",main="Tapered Data Series"); lines(dat,lty=2); lines(tt,col="blue")
hist(dat[,2],freq=F,xlab="Tapered Value",main="Distribution of Tapered Values"); lines(density(dat[,2], bw="nrd0"),col="red")
### Normal probabilty plot (Normal Q-Q Plot)
qqnorm(dat[,2]); qqline(dat[,2], col="red")
}
return(dat)
### END function dpssTaper
}
Any scripts or data that you put into this service are public.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.