Adding a linestring by st_read in Shiny/Leaflet

Question

I have a large shapefile. For a better perfomance I try to load data with st_read() from sf package. The official documentation states that it should be very easy to integrate the shapefile into Leaflet/Shiny. Nevertheless, it does not work.

Error message: missing value where TRUE/FALSE needed

It works with rgdal, but the performance is not that good. Link

I hope that someone can help me out.

small TestData

library(shiny)
library(leaflet)
library(sf)

shapefile <- st_read("pathToshape")

shinyApp(
  ui <-fluidRow(
    column(8,leafletOutput("map", height="600px"))
  ),

server <- function(input, output, session) {
  output$map <- renderLeaflet({
    leaflet() %>% 
      addTiles() %>% 
      setView(lng=16.357795000076294, lat=48.194883921677935, zoom = 15) %>%
      addPolylines(data=shapefile, layerId = shapefile$id, group = shapefile$zeitver, color="red", weight=3,opacity=1)
  })
})

Answer 1

Your test data is a dead link now, but I had a similar issue trying to plot sf linestrings and polygons in leaflet. The full error was

Error in if (length(nms) != n || any(nms == "")) stop("'options' must be a fully named list, or have no names (NULL)") : 
missing value where TRUE/FALSE needed

I was able to successfully plot my geometries by dropping the Z dimension from the line and polygon with st_zm. Here is an example:

library(sf)
library(leaflet)

# create sf linestring with XYZM dimensions 
badLine <- st_sfc(st_linestring(matrix(1:32, 8)), st_linestring(matrix(1:8, 2)))

# check metadata for badLine
> head(badLine)

Geometry set for 2 features 
    geometry type:  LINESTRING
    dimension:      XYZM
    bbox:           xmin: 1 ymin: 3 xmax: 8 ymax: 16
    epsg (SRID):    NA
    proj4string:    NA
    LINESTRING ZM (1 9 17 25, 2 10 18 26, 3 11 19 2...
    LINESTRING ZM (1 3 5 7, 2 4 6 8)

# attempt map; will fail
> leaflet() %>%
+   addTiles() %>%
+   addPolygons(data = badLine)

Error in if (length(nms) != n || any(nms == "")) stop("'options' must be a fully named list, or have no names (NULL)") : 
  missing value where TRUE/FALSE needed

# try again!

# drop Z and M dimensions from badLine
goodLine <- st_zm(badLine, drop = T, what = "ZM")

# map; will plot successfully!
leaflet() %>%
  addTiles() %>%
  addPolygons(data = goodLine)

Answer 2

Loading the data with st_read creates sf objects, very different things from loading with readOGR or shapefile or readShapePoly, which produce sp objects. addPolylines currently only supports sp objects.

Even if it did support sf objects it probably wouldn't speed your application up much, since leaflet needs everything in geoJSON format. You may have hit a scaling limit of the shiny-leaflet system and need to rethink your application.