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The plot method for a brokenstick object plots the observed and fitted trajectories of one or more groups.


# S3 method for brokenstick
plot(x, newdata = NULL, ...)



An object of class brokenstick.


Optional. A data frame in which to look for variables with which to predict. The training data are used if omitted and if object$light is FALSE.


Extra arguments passed down to predict.brokenstick() and plot_trajectory().


An object of class ggplot2::ggplot.


By default, plot(fit) will plot the observed and fitted data for the first three groups in the data. The default setting drops the fitted value at the right boundary knot from the display.


Stef van Buuren 2023


if (FALSE) {
# fit model on raw hgt with knots at 0, 1, 2 and 3 years
fit1 <- brokenstick(hgt ~ age | id, smocc_200, knots = 0:2)
gp <- c(10001, 10005, 10022)
plot(fit1, group = gp, xlab = "Age (years)", ylab = "Length (cm)")

# fit model on standard deviation score
fit2 <- brokenstick(hgt_z ~ age | id, smocc_200, knots = 0:2)
plot(fit2, group = gp, xlab = "Age (years)", ylab = "Length (SDS)")

# built-in model with 11 knots
plot(fit_200, group = gp, xlab = "Age (years)", ylab = "Length (SDS)")

# black and white version
plot(fit_200, group = gp, xlab = "Age (years)", ylab = "Length (SDS)",
    color_y = rep("black", 2), shape_y = 1, linetype_y = 3,
    color_yhat = rep("grey20", 2), shape_yhat = NA)