renderTmap: Wrapper functions for using *tmap* in *shiny*

In tmap: Thematic Maps

Wrapper functions for using tmap in shiny

Description

• tmapOutput() creates a UI element

• renderTmap() renders a tmap map

• tmapProxy() updates a tmap map in view mode

Adding layers is as usual via the map layer functions like tm_polygons(). Removing layers can be done, removing with tm_remove_layer().

Usage

renderTmap(
  expr,
  env = parent.frame(),
  quoted = FALSE,
  execOnResize = TRUE,
  mode = NA
)

tmapOutput(outputId, width = "100%", height = 400, mode = NA)

tmapProxy(mapId, session = shiny::getDefaultReactiveDomain(), x, mode = NA)

tm_remove_layer(zindex)

Arguments

expr	A tmap object. A tmap object is created with qtm() or by stacking tmap-elements.
env	The environment in which to evaluate expr
quoted	Is expr a quoted expression (with quote())? This is useful if you want to save an expression in a variable
execOnResize	If TRUE (default), when the plot is resized, the map is regenerated. When set to FALSE the map is rescaled: the aspect ratio is kept, but the layout will be less desirable.
mode	tmap mode, see tmap_mode() If not defined, the current mode is used
outputId	Output variable to read from
width, height	the width and height of the map
mapId	single-element character vector indicating the output ID of the map to modify (if invoked from a Shiny module, the namespace will be added automatically)
session	the Shiny session object to which the map belongs; usually the default value will suffice
x	the tmap object that specifies the added and removed layers.
zindex	the z index of the pane in which the layer is contained that is going to be removed. It is recommended to specify the zindex for this layer when creating the map (inside renderTmap()).

Details

Two features from tmap are not (yet) supported in Shiny: small multiples (facets) and colored backgrounds (argument bg.color of tm_layout()). Workarounds for small multiples: create multiple independent maps or specify as.layers = TRUE in tm_facets().

Examples

if (interactive() && require("shiny")) {

	data(World)
	world_vars <- setdiff(names(World), c("iso_a3", "name", "sovereignt", "geometry"))

	current.mode <- tmap_mode("plot")

	shinyApp(
		ui = fluidPage(
			tmapOutput("map", height = "600px"),
			selectInput("var", "Variable", world_vars)
		),
		server <- function(input, output, session) {
			output$map <- renderTmap({
				tm_shape(World) +
					tm_polygons(input$var, zindex = 401)
			})
		}
	)

	tmap_mode("view")

	shinyApp(
		ui = fluidPage(
			tmapOutput("map", height = "600px"),
			selectInput("var", "Variable", world_vars)
		),
		server <- function(input, output, session) {
			output$map <- renderTmap({
				tm_shape(World, id = "iso_a3") +
					tm_polygons(fill = world_vars[1], zindex = 401)
			})
			observe({
				var <- input$var
				tmapProxy("map", session, {
					tm_remove_layer(401) +
						tm_shape(World, id = "iso_a3") +
						tm_polygons(fill = var, zindex = 401)
				})
			})
		},options = list(launch.browser=TRUE)
	)

	tmap_mode(current.mode)
}

tmap documentation built on April 4, 2025, 2:05 a.m.