#' The De Jong map.
#'
#' @param n Number of points in the time series.
#' @param xi The initial value for x
#' @param yi The initival value for y
#' @param a The value of the parameter a
#' @param b The value of the parameter b
#' @param c The value of the parameter c
#' @param d The value of the parameter d
#' @param add.timestep Add a column indicating the time step?
#' @param plot Plot the time series?
#' @return A n-by-2 data frame containing the values of the x and y components.
#' @export
dejong_map <- function(n = 1000,
xi = -5,
yi = 0.1,
a = 1.4,
b = -2.3,
c = 2.4,
d = -2.1,
add.timestep = FALSE,
plot = FALSE) {
x = vector(length = n)
y = vector(length = n)
x[1] = xi
y[1] = yi
for (i in 2:n) {
x[i] = sin(a * y[i - 1]) - cos(b * x[i - 1])
y[i] = sin(c * x[i - 1]) - cos(d * y[i - 1])
}
if (add.timestep) {
timestep = 1:n
df = data.frame(timestep, x, y)
names(df) = c("t", "x", "y")
} else {
df = data.frame(x,y)
names(df) = c("x", "y")
}
if (plot & add.timestep) {
p = ggplot2::ggplot() +
ggplot2::geom_line(data = df, mapping = ggplot2::aes(x = t, y = x, col = "x")) +
ggplot2::geom_line(data = df, mapping = ggplot2::aes(x = t, y = y, col = "y")) +
ggplot2::theme_bw() +
ggplot2::ylab("value") +
ggplot2::ggtitle("DeJong map")
print(p)
} else if (plot & !add.timestep) {
warning("cannot plot without adding timestep.")
}
return(df)
}
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.