pomdp (version 1.0.0)

plot_policy_graph: Visualize a POMDP Policy Graph

Description

The function plots the POMDP policy graph in a POMDP. It uses plot in igraph with appropriate plotting options.

Usage

plot_policy_graph(
  x,
  belief = TRUE,
  legend = TRUE,
  engine = c("igraph", "visNetwork"),
  col = NULL,
  ...
)

Arguments

x

object of class POMDP containing a solved POMDP problem.

belief

logical; display belief proportions as a pie chart in each node. This requires belief space sampling and may be slow.

legend

logical; display a legend for colors used belief proportions?

engine

The plotting engine to be used.

col

colors used for the states.

…

plotting options passed on to the plotting engine (see Details section).

Details

The function currently only plots converged policy graphs.

The policy graph nodes represent segments in the value function. Each segment represents one or more believe states. The pie chart in each node (if available) represent the average belief proportions of the belief states belonging to the node/segment.

The built in plotting engines are igraph and visNetwork. The additional arguments specified in ... are passed on to the engine plotting function. For igraph this is igraph::plot.igraph(). For visNetwork this is visNetwork::visIgraph().

Other plotting libraries can be used by creating a policy graph (as an igraph object) using policy_graph() and converting it into a suitable representation for that library.

See Also

Other policy: optimal_action(), plot_value_function(), policy_graph(), policy(), reward(), solve_POMDP(), solve_SARSOP()

Examples

# NOT RUN {
data("Tiger")
sol <- solve_POMDP(model = Tiger)
sol

## policy graph
policy_graph(sol)

## visualization
plot_policy_graph(sol)

## use a different graph layout (circle and manual; needs igraph)
library("igraph")
plot_policy_graph(sol, layout = layout.circle)
plot_policy_graph(sol, layout = rbind(c(1,1), c(1,-1), c(0,0), c(-1,-1), c(-1,1)))

## hide labels and legend
plot_policy_graph(sol, edge.label = NA, vertex.label = NA, legend = FALSE)

## add a plot title
plot_policy_graph(sol, main = sol$name)

## custom larger vertex labels (A, B, ...)
plot_policy_graph(sol,
  vertex.label = LETTERS[1:nrow(policy(sol)[[1]])],
  vertex.label.cex = 2,
  vertex.label.color = "white")

## plotting using the graph object
## (e.g., using the graph in the layout and to change the edge curvature)
pg <- policy_graph(sol)
plot(pg,
  layout = layout_as_tree(pg, root = 3, mode = "out"),
  edge.curved = curve_multiple(pg, .2))

## changes labels
plot(pg,
  edge.label = abbreviate(E(pg)$label),
  vertex.label = sol$solution$pg$action,
  vertex.size = 10)

## plot interactive graphs using the visNetwork library
plot_policy_graph(sol, engine = "visNetwork")

## add smooth edges and a layout (note, engine can be abbreviated)
plot_policy_graph(sol, engine = "vis", layout = "layout_in_circle", smooth = TRUE)
# }