Functions for using forest plots in Shiny applications.

Output and Render

forestOutput

Create a Shiny output element for a forest plot.

forestOutput(outputId, width = "100%", height = "400px")
Argument Description
outputId Output variable name
width Widget width (CSS units)
height Widget height (CSS units)

renderForest

Render a forest plot in Shiny.

renderForest(expr, env = parent.frame(), quoted = FALSE)
Argument Description
expr Expression that returns a forest_plot()
env Environment for evaluation
quoted Whether expr is already quoted

Split Forest in Shiny

splitForestOutput

Create a Shiny output element for a split forest plot.

splitForestOutput(outputId, width = "100%", height = "600px")
Argument Description
outputId Output variable name
width Widget width (CSS units)
height Widget height (CSS units)

renderSplitForest

Render a split forest plot in Shiny.

renderSplitForest(expr, env = parent.frame(), quoted = FALSE)
Argument Description
expr Expression that returns a split_table() result rendered with forest_plot()
env Environment for evaluation
quoted Whether expr is already quoted

splitForestProxy

Create a proxy object for an existing split forest plot.

splitForestProxy(id, session = shiny::getDefaultReactiveDomain())
Argument Description
id The widget ID
session Shiny session (default: current session)

split_table_select

Select a specific sub-plot in a split forest.

split_table_select(proxy, key)
Argument Description
proxy A split_table_proxy object
key The key of the sub-plot to select (e.g., "Americas" or "Female/Young")

Proxy Functions

Proxy functions allow updating a forest plot without full re-rendering.

forestProxy

Create a proxy object for an existing forest plot.

forestProxy(id, session = shiny::getDefaultReactiveDomain())
Argument Description
id The widget ID
session Shiny session (default: current session)

forest_update_data

Update the data in an existing forest plot.

forest_update_data(proxy, spec)
Argument Description
proxy A forest_proxy object
spec A WebSpec object from web_spec()

forest_toggle_subgroup

Toggle a subgroup’s collapse state.

forest_toggle_subgroup(proxy, subgroup_id, collapsed = NULL)
Argument Description
proxy A forest_proxy object
subgroup_id The subgroup ID to toggle
collapsed TRUE to collapse, FALSE to expand, NULL to toggle

forest_filter

Apply a filter to the forest plot.

forest_filter(proxy, field, operator, value)
Argument Description
proxy A forest_proxy object
field Field to filter on
operator Filter operator: "eq", "neq", "gt", "lt", "contains"
value Filter value

forest_clear_filter

Clear all filters from the forest plot.

forest_clear_filter(proxy)

forest_sort

Sort the forest plot by a column.

forest_sort(proxy, column, direction)
Argument Description
proxy A forest_proxy object
column Column to sort by
direction Sort direction: "asc", "desc", or "none"

Examples

Basic Shiny App

Code 
library(shiny)
library(tabviz)

ui <- fluidPage(
  titlePanel("Forest Plot Demo"),
  sidebarLayout(
    sidebarPanel(
      selectInput("theme", "Theme:",
        choices = c("Default", "JAMA", "Lancet", "Modern")
      )
    ),
    mainPanel(
      forestOutput("forest", height = "500px")
    )
  )
)

server <- function(input, output, session) {
  data <- data.frame(
    study = c("Study A", "Study B", "Study C"),
    hr = c(0.72, 0.85, 0.91),
    lower = c(0.55, 0.70, 0.75),
    upper = c(0.95, 1.03, 1.10)
  )

  output$forest <- renderForest({
    theme <- switch(input$theme,
      "Default" = web_theme_default(),
      "JAMA" = web_theme_jama(),
      "Lancet" = web_theme_lancet(),
      "Modern" = web_theme_modern()
    )

    forest_plot(data,
      point = "hr", lower = "lower", upper = "upper",
      label = "study",
      null_value = 1, scale = "log",
      theme = theme
    )
  })
}

shinyApp(ui, server)

Using Proxy for Updates

Code 
library(shiny)
library(tabviz)

ui <- fluidPage(
  forestOutput("forest"),
  actionButton("filter_btn", "Filter HR < 1"),
  actionButton("clear_btn", "Clear Filter")
)

server <- function(input, output, session) {
  data <- reactive({
    data.frame(
      study = c("Study A", "Study B", "Study C", "Study D"),
      hr = c(0.72, 0.85, 1.15, 0.91),
      lower = c(0.55, 0.70, 0.90, 0.75),
      upper = c(0.95, 1.03, 1.45, 1.10)
    )
  })

  output$forest <- renderForest({
    forest_plot(data(),
      point = "hr", lower = "lower", upper = "upper",
      label = "study",
      null_value = 1, scale = "log"
    )
  })

  observeEvent(input$filter_btn, {
    forestProxy("forest") |>
      forest_filter("hr", "lt", 1)
  })

  observeEvent(input$clear_btn, {
    forestProxy("forest") |>
      forest_clear_filter()
  })
}

shinyApp(ui, server)

Dynamic Data Updates

Code 
library(shiny)
library(tabviz)

server <- function(input, output, session) {
  # Reactive data source
  filtered_data <- reactive({
    base_data |>
      filter(category == input$category)
  })

  # Update via proxy for smooth transitions
  observe({
    spec <- web_spec(
      filtered_data(),
      point = "hr", lower = "lower", upper = "upper",
      label = "study",
      scale = "log", null_value = 1
    )

    forestProxy("forest") |>
      forest_update_data(spec)
  })
}

See Also