Add line — add_line • mapdeck

The Line Layer renders raised lines joining pairs of source and target coordinates

add_line(
  map,
  data = get_map_data(map),
  layer_id = NULL,
  origin,
  destination,
  id = NULL,
  stroke_colour = NULL,
  stroke_width = NULL,
  stroke_opacity = NULL,
  tooltip = NULL,
  auto_highlight = FALSE,
  highlight_colour = "#AAFFFFFF",
  palette = "viridis",
  na_colour = "#808080FF",
  legend = FALSE,
  legend_options = NULL,
  legend_format = NULL,
  update_view = TRUE,
  focus_layer = FALSE,
  digits = 6,
  transitions = NULL,
  brush_radius = NULL
)

Arguments

map	a mapdeck map object
data	data to be used in the layer. All coordinates are expected to be EPSG:4326 (WGS 84) coordinate system
layer_id	single value specifying an id for the layer. Use this value to distinguish between shape layers of the same type. Layers with the same id are likely to conflict and not plot correctly
origin	vector of longitude and latitude columns, and optionally an elevation column, or an `sfc` column
destination	vector of longitude and latitude columns, and optionally an elevatino column, or an `sfc` column
id	an id value in `data` to identify layers when interacting in Shiny apps.
stroke_colour	variable or hex colour to use as the ending stroke colour.
stroke_width	width of the line in metres
stroke_opacity	Either a string specifying the column of `data` containing the opacity of each shape, or a single value in [0,255], or [0, 1), to be applied to all the shapes. Default 255. If a hex-string is used as the colour, this argument is ignored and you should include the alpha on the hex string
tooltip	variable of `data` containing text or HTML to render as a tooltip
auto_highlight	logical indicating if the shape under the mouse should auto-highlight
highlight_colour	hex string colour to use for highlighting. Must contain the alpha component.
palette	string or matrix. String will be one of `colourvalues::colour_palettes()`. A matrix must have at least 5 rows, and 3 or 4 columns of values between [0, 255], where the 4th column represents the alpha. You can use a named list to specify a different palette for different colour options (where available), e.g. list(fill_colour = "viridis", stroke_colour = "inferno")
na_colour	hex string colour to use for NA values
legend	either a logical indiciating if the legend(s) should be displayed, or a named list indicating which colour attributes should be included in the legend.
legend_options	A list of options for controlling the legend.
legend_format	A list containing functions to apply to legend values. See section legend
update_view	logical indicating if the map should update the bounds to include this layer
focus_layer	logical indicating if the map should update the bounds to only include this layer
digits	number of digits for rounding coordinates
transitions	list specifying the duration of transitions.
brush_radius	radius of the brush in metres. Default NULL. If supplied, the arcs will only show if the origin or destination are within the radius of the mouse. If NULL, all arcs are displayed

Details

add_line supports POINT sf objects

MULTIPOINT objects will be treated as single points. That is, if an sf object has one row with a MULTIPOINT object consisting of two points, this will be expanded to two rows of single POINTs. Therefore, if the origin is a MULTIPOINT of two points, and the destination is a single POINT, the code will error as there will be an uneven number of rows

transitions

The transitions argument lets you specify the time it will take for the shapes to transition from one state to the next. Only works in an interactive environment (Shiny) and on WebGL-2 supported browsers and hardware.

The time is in milliseconds

Available transitions for line

list( origin = 0, destination = 0, stroke_colour = 0, stroke_width = 0 )

legend

The legend_options can be used to control the appearance of the legend. This should be a named list, where the names are one of

css - a string of valid css for controlling the appearance of the legend
title - a string to use for the title of the legend
digits - number to round the legend values to

If the layer allows different fill and stroke colours, you can use different options for each. See examples in add_arc.

The legend_format can be used to control the format of the values in the legend. This should be a named list, where the names are one of

fill_colour
stroke_colour

depending on which type of colouring the layer supports.

The list elements must be functions to apply to the values in the legend.

id

The id is returned to your R session from an interactive shiny environment by observing layer clicks. This is useful for returning the data.frame row relating to the cliked shape.

From within a shiny server you would typically use observeEvent({input$map_arc_click}), where 'map' is the map_id supplied to mapdeckOutput(), and 'arc' is the layer you are clicking on

Examples

# \donttest{

## You need a valid access token from Mapbox
key <- 'abc'
set_token( key )

url <- 'https://raw.githubusercontent.com/plotly/datasets/master/2011_february_aa_flight_paths.csv'
flights <- read.csv(url)
flights$id <- seq_len(nrow(flights))
flights$stroke <- sample(1:3, size = nrow(flights), replace = T)

mapdeck(style = mapdeck_style("dark"), pitch = 45 ) %>%
  add_line(
    data = flights
    , layer_id = "line_layer"
    , origin = c("start_lon", "start_lat")
    , destination = c("end_lon", "end_lat")
    , stroke_colour = "airport1"
    , stroke_width = "stroke"
    , auto_highlight = TRUE
 )

## Using a 2-sfc-column sf object
library(sfheaders)

sf_flights <- sfheaders::sf_point( flights, x = "start_lon", y = "start_lat", keep = TRUE )
destination <- sfheaders::sfc_point( flights, x = "end_lon", y = "end_lat" )

sf_flights$destination <- destination

mapdeck() %>%
 add_line(
   data = sf_flights
   , origin = 'geometry'
   , destination = 'destination'
   , layer_id = 'arcs'
   , stroke_colour = "airport1"
)
# }