Filter a Power Spectrum Object

Filter a Power Spectrum Object

Usage

FilterSpec(spec, spans, method = 3, keep_low_f = TRUE)

Arguments

spec

A spec object

spans

vector of odd integers giving the widths of modified Daniell smoothers to be used to smooth the periodogram.

method

single integer for choosing an endpoint constraint method. Available choices are integers 0-4, see details of ApplyFilter

keep_low_f

Keep filtered (smoothed) low frequencies or replace with unfiltered

Value

A spec object (list)

See also

Other functions to filter / smooth spectra: FilterSpecLog(), LogSmooth()

Author

Andrew Dolman

Examples

## Comparison of the four methods - for power spectra, methods 0, 2 or 3 make the most sense
library(PaleoSpec)

a <- 100
b <- 1
N <- 1e03
set.seed(20230625)
ts1 <- SimPLS(N, beta = b, alpha = a)
sp1 <- SpecMTM(ts(ts1), bin.width = 1)
LPlot(sp1)
abline(log10(a), -b, col = "green")

fl <- seq(3, 9, by = 2)
sp1_f3_0 <- FilterSpec(sp1, spans = fl, method = 0)
sp1_f3_1 <- FilterSpec(sp1, spans = fl, method = 1)
sp1_f3_2 <- FilterSpec(sp1, spans = fl, method = 2)
sp1_f3_3 <- FilterSpec(sp1, spans = fl, method = 3)
sp1_f3_4 <- FilterSpec(sp1, spans = fl, method = 4)

LPlot(sp1)
LLines(sp1_f3_0, col = "blue")
LLines(sp1_f3_1, col = "green", lty = 2)
LLines(sp1_f3_2, col = "red", lty = 3)
LLines(sp1_f3_3, col = "orange", lty = 4)
LLines(sp1_f3_4, col = "gold", lty = 5)


## Comparison of keeping the filtered values in the reflected end portions or not
sp1_f3_0T <- FilterSpec(sp1, spans = fl, method = 0, keep_low_f = TRUE)
sp1_f3_0F <- FilterSpec(sp1, spans = fl, method = 0, keep_low_f = FALSE)
LPlot(sp1_f3_0F)
LLines(sp1_f3_0T, col = "red")

sp1_f3_2T <- FilterSpec(sp1, spans = fl, method = 2, keep_low_f = TRUE)
sp1_f3_2F <- FilterSpec(sp1, spans = fl, method = 2, keep_low_f = FALSE)
LPlot(sp1_f3_2F)
LLines(sp1_f3_2T, col = "red")