Find and interpolate stimulation signals

Usage

interpolate_stimulation(
  x,
  sample_rate,
  duration = 40/sample_rate,
  ord = 4L,
  nknots = 100,
  nsd = 1,
  nstim = NULL,
  regularization = 0.5
)

Arguments

x: numerical vector representing a analog signal
sample_rate: sampling frequency
duration: time in second: duration of interpolation
ord: spline order, default is 4
nknots: a rough number of knots to use, default is 100
nsd: number of standard deviation to detect stimulation signals, default is 1
nstim: number of stimulation pulses, default is to auto-detect
regularization: regularization parameter in case of inverting singular matrices, default is 0.5

Value

Interpolated signal with an attribute of which sample points are interpolated

Examples


x0 <- rnorm(1000) / 5 + sin(1:1000 / 300)

# Simulates pulase signals
x <- x0
x[400:410] <- -100
x[420:430] <- 100

fitted <- interpolate_stimulation(x, 100, duration = 0.3, nknots = 10, nsd = 2)

par(mfrow = c(2, 1))

plot(fitted, type = 'l', col = 'blue', lwd = 2)
lines(x, col = 'red')
lines(x0, col = 'black')
legend("topleft", c("Interpolated", "Observed", "Underlying"),
       lty = 1, col = c("blue", "red", "black"))

pwelch(x0, 100, 200, 100, plot = 1, col = 'black', ylim = c(-50, 50))
pwelch(x, 100, 200, 100, plot = 2, col = 'red')
pwelch(fitted, 100, 200, 100, plot = 2, col = 'blue')