how to set zoom level/view of leaflet map - r

Question

I have a map in leaflet in RShiny which have markers plotted and once I click a marker it adds circles to map showing all the related points to the marker.
What I want to do is to set zoom/view of the map in such a way that all the related circles are visible.
The number of circles varies as per markers i.e. some marker have 1 or 2 circles while some have more. Also, the location of circles varies across the USA so they can be placed in one city or another state.
Following is the code I am using to add circles to existing map
proxy <-leafletProxy("map",data = df)%>%
clearMarkers()%>%
addCircleMarkers(lat = ~lat,lng = ~lng,layerId = ~circle_pt,fillColor =
'green',opacity = 0.5,color = 'red',fillOpacity = 1)%>% clearPopups()%>%
addPopups(lat=~lat,lng=~lng,~as.character(circle_pt))
map=original map with markers
df=lat lng of circles with associated properties of selected marker in map
I want to set zoom level as shown in figure 2.
Kindly help me to identify how to calculate optimal zoom level in leaflet in shiny.
Regards,

Answer 1

If you want to set your initial view, you can use:
setView(lng, lat, zoom = zoom_level)
which is straight from the documentation.
Unless you provide more information, nobody will be able to understand the part where you're saying "in such a way that all the related circles are visible."

Answer 2

I'm not sure how you're app works and whats in the original call to leaflet. But maybe the following example might help you.
I store the click on the markers, filter the data according to the clicked layerId, get the min/max lat/long of the resulting data and then use fitBounds() to set the "zoom" level. (You could also use flyToBounds with the same arguments, which should make a smoother transition to the selected markers, but its still too buggy for me at least)
library(shiny)
library(shinyjs)
library(leaflet)
cords <- data.frame(
lng = runif(100, 14, 18),
lat = runif(100, 54, 58),
circle_pt = sample(1:20, size = 100, replace = T)
)
ui <- fluidPage(
leafletOutput("map", height = "700px")
)
server <- function(input, output, session) {
output$map <- renderLeaflet({
leaflet(data = cords) %>%
addTiles() %>%
addCircleMarkers(lat = ~lat,lng = ~lng, layerId = ~circle_pt, fillColor = 'green',
opacity = 0.5,color = 'red',fillOpacity = 1)
})
observeEvent(input$map_marker_click, {
clickid = input$map_marker_click$id
cordsNew = cords[cords$circle_pt==clickid,]
maxLong = max(cordsNew$lng)
maxLat = max(cordsNew$lat)
minLong = min(cordsNew$lng)
minLat = min(cordsNew$lat)
proxy <-leafletProxy("map", data = cordsNew)
proxy %>%
addCircleMarkers(lat = ~lat,lng = ~lng, layerId = ~circle_pt, fillColor = 'green',
opacity = 0.5,color = 'red',fillOpacity = 1) %>%
fitBounds(minLong,minLat,maxLong,maxLat) %>%
clearPopups() %>%
addPopups(lat=~lat,lng=~lng,~as.character(circle_pt))
})
}
shinyApp(ui = ui, server = server)

Answer 3

may be you can define an interval varint <- findInterval() and that pass to setView
varint <- findInterval()
setView(lng= lng,lat = lat, zoom = varint)
in findInterval, try to put some range of data with the distance between all points
EDIT:
try to calculate the distance between the farthest points that appear.
proxy <-leafletProxy("map",data = df) %>%
setView(
lng = click$lng,
lat=click$lat,
zoom=findInterval(someaverageofyourpoints, c(25,75,100,250,400,750,1000))
)
you can sum other values to findinterval, findinterval()+ 1 .. 2.. 4 ...5 for setting zoom level if findintervalset a tiny value