rr-leaflet

Changing size / aspect ratio of leaflet

I'm looking to produce a rectangular leaflet output (i.e., aspect ratio of ~0.7). My workflow is as follows: I'm creating static maps, to be saved to image files. Then, I'll use 2 map outputs shown side-by-side in a Shiny app. This means that each output needs to be rectangular, instead of square as seems to be the default.

I tried using both fitBounds and setMaxBounds options with no luck. I also played with the height and width parameters of leaflet, but seemingly could not set them to an aspect ratio different from 1 (for example, width = 50% made the map half the screen wide but also half tall; setting width = 50%, height = 75% resulted in a blank page).

Example map:

library(leaflet)
library(webshot)
library(mapview)
df <- expand.grid(x = seq(-10, 10, 1), y = seq(-10, 10, 1))

m <- leaflet() %>% 
    addTiles() %>%
    addMarkers(data = df, lng = ~x, lat = ~y)  %>%
    fitBounds(lng1 = -12, lat1 = -20, lng2 = 12, lat2 = 20)  
    # setMaxBounds(lng1 = -12, lat1 = -20, lng2 = 12, lat2 = 20)        
    
mapshot(m, file = "Rplot.png")
Solution

  • Another way would be to use the selectorargument= "One or more CSS selectors specifying a DOM element to set the clipping rectangle to. The screenshot will contain these DOM elements". passed to webshot

    library(leaflet)

df <- expand.grid(x = seq(-10, 10, 1), y = seq(-10, 10, 1))

width <- 10
height <- 4
timesPXL <- 150

m <- leaflet(
 width = paste0(width*timesPXL ,"px"), 
 height = paste0(height*timesPXL ,"px")) %>% 
    addTiles() %>%
    addMarkers(data = df, lng = ~x, lat = ~y)  %>%
    fitBounds(lng1 = -12, lat1 = -20, lng2 = 12, lat2 = 20)  
    
mapview::mapshot(m, file = "Rplot.png", selector = ".leaflet-container")

    out