pile.down {DecomposeR}

Destacks a pile.up() signal

Description

Destacks a signal stacked by pile.up by averaging each repetition back to n multiples.

Usage

pile.down(x, stack, even, n = length(unique(stack$id)) - 2)

Arguments

x

Treated signal

stack

Initial stack from which the x signal is from

even

Whether the x signal comes from even extension part of the initial stack (if FALSE, it would come from the odd extension part)

n

The multiple of destacking (has to be a multiple of n/2 (n being the parameter used in pile.up), in other words a multiple of length(unique(stack$id)) - 2 (minus 2 as the upper an lower extension are to be removed)

Value

a matrix or a vector of the destacked signal

Examples

set.seed(42)

n <- 200
t <- seq_len(n)

p1 <- 25
p2 <- 75

xy <- (1 + 0.6 * sin(t*2*pi/p2)) * sin(t*2*pi/p1)  + 2 * sin(t*2*pi/p2) +
  rnorm(n, sd = 0.5)

inter_dt <- round(runif(length(xy), min = 0.5, max = 1.5),1)
inter_dt[20] <- 20

dt <- cumsum(inter_dt)

opar <- par()$mfrow
par(mfrow = c(1,1))

res <- pile.up(xy, dt, 4)

par(mfrow = c(2,1))
plot(res$ndt, res$even, type = "l", col = "blue")
plot(res$ndt, res$odd,  type = "l", col = "red")

par(mfrow = c(opar))

# Small number of repetitions ----

opar <- par("mfrow")
par(mfrow = c(1,2))

stack <- pile.up(xy, dt, 10)

signal <- stack$even + runif(length(stack$even), -3, 3)

res <- pile.down(signal, stack, even = TRUE, n = 5)

plot(xy, dt, type = "l", lwd = 2, main = "Low number of repetitions")
lines(res, dt,  type = "l", lty = 5, col = "red")

# High number of repetitions ----

stack <- pile.up(xy, dt, 1000)

signal <- stack$even + runif(length(stack$even), -3, 3)

res <- pile.down(signal, stack, even = TRUE, n = 500)

plot(xy, dt, type = "l", lwd = 2, main = "High number of repetitions")
lines(res, dt,  type = "l", lty = 5, col = "red")

par(mfrow = c(opar))