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Plot Divergent Transitions

Source: R/plot_diagnostics.R
plot_divergences.Rd

Creates visualizations to investigate divergent transitions. Parallel coordinates and scatter plots highlight where in parameter space divergences occur.

Usage

plot_divergences(fit, pars = NULL, type = c("parcoord", "scatter"))

Arguments

fit

A tulpa_fit object (HMC backend).

pars

Character vector of parameter names. If NULL, uses variance parameters.

type

Plot type: "parcoord" (parallel coordinates) or "scatter".

Value

A ggplot object or base R plot (invisible).

Details

Divergent transitions indicate regions of high posterior curvature that the sampler cannot efficiently explore. Common causes:

  • Very narrow funnels (hierarchical models)

  • Strong correlations

  • Multi-modality

See also

plot_pairs(), n_divergent()

Examples

# \donttest{
set.seed(123)
df <- data.frame(x = rnorm(60))
df$y <- rpois(60, exp(0.5 + 0.3 * df$x))
fit <- tulpa(y ~ x, data = df, family = "poisson", mode = "hmc",
             control = list(n_iter = 500L, warmup = 250L, n_chains = 2L,
                            seed = 1L))
plot_divergences(fit)
plot_divergences(fit, type = "scatter")
# }