itsadug (version 0.8)

plot_diff2: Plot difference surface based on model predictions.

Description

Plot difference surface based on model predictions.

Usage

plot_diff2(model, view, comp, cond = NULL, plotCI = FALSE, f = 1.96,
  color = "topo", nCol = 100, col = NULL, add.color.legend = TRUE,
  n.grid = 30, nlevels = 10, zlim = NULL, main = NULL,
  print.summary = TRUE)

Arguments

model

A GAMM model, resulting from the functions gam or bam.

view

Name of continuous predictors that should be plotted on the x- and y-axes. Vector of two values.

comp

Named list with the grouping predictor (categorical variable) and the 2 levels to calculate the difference for.

cond

Named list of the values to use for the other predictor terms (not in view).

plotCI

Logical: whether or not to plot confidence intervals.

f

A number to scale the standard error. Defaults to 1.96, resulting in 95% confidence intervals. For 99% confidence intervals use a value of 2.58.

color

Colorpalette

nCol

Range of colors of background of contour plot.

col

Line color.

add.color.legend

Logical: whether or not to add a color legend. Default is TRUE. If FALSE (omitted), one could use the function gradientLegend to add a legend manually at any position.

n.grid

Resolution.

nlevels

Levels of contour lines.

zlim

A two item array giving the lower and upper limits for the z- axis scale. NULL to choose automatically.

main

Title of plot.

print.summary

Logical: whether or not to print a summary.

Value

• If the result is not being plotted, a list is returned with the estimated difference (est) and the standard error over the estimate (se.est) and the x-values (x) is returned.

See Also

Other functions for interpreting nonlinear effects: fvisgam, vis.gam2; plotDiff, plot_diff; plot_parametric; plot_smooth; pvis.gam, pvisgam

Examples

data(simdat)
m1 <- bam(Y ~ Group + te(Time, Trial, by=Group),
    data=simdat)
plot_diff2(m1, view=c('Time', 'Trial'),
    comp=list(Group=c("Children", "Adults")))
# see the vignette for examples:
vignette("plotfunctions", package="itsadug")