Integrate a leaflet map into Shiny without the pipe operator %>%

Question

OK I have been able to integrate maps into Shinny, but always when I use the pipe operator. This time I have a map that has a for loop and as I am new to R, I didn't know how to use the pipe operator in that case.

The leaflet map is as follows:

libraries used:

library(data.table)
library(leaflet)
library(shiny)

data.table:

lat<-c(40.41766, 40.43305 ,40.43687, 40.39563, 40.39088, 40.39215, 40.39458, 40.40451, 40.40627, 40.40864)
lng<-c(-3.701328, -3.709352, -3.708531, -3.736556, -3.734796, -3.741867, -3.741222, -3.705399, -3.710980, -3.710310)
colors<-c("#3D00FFFF","#52FF00FF","#3D00FFFF","#0052FFFF","#52FF00FF","#52FF00FF","#52FF00FF","#0052FFFF","#3D00FFFF","#0052FFFF")
name<-as.factor(c("Rafa","Luis","Rafa","Belen","Luis","Luis","Luis","Belen","Rafa","Belen"))
hour_range<-c("Sleeping_Hours","Morning_rush_hours","Morning_Working_Hours","Sleeping_Hours","Morning_rush_hours","Morning_Working_Hours","Sleeping_Hours","Morning_rush_hours","Morning_Working_Hours","Morning_Working_Hours")

data<- data.table(name,lat,lng,hour_range,colors)

leaflet map:

map<-  leaflet(data)
map<- addTiles(map)
for( name in unique(data$name)){ 
  map<- addPolylines(map, lng=~lng,lat=~lat,data=data[data$name==name & data$hour_range=="Morning_rush_hours",],color=~colors)
  map<-addPolylines(map, lng=~lng,lat=~lat,data=data[data$name==name & data$hour_range=="Sleeping_Hours",],color=~colors)
}

map

This map works fine the problem is that I don't know how to integrate it with shinny, cause I am not using pipes. And it appears me an error called:

Argument "map" is missing with no default. Because Shiny doesn't see my map.

Answer 1

Try the following example. And also try to run it, when you uncomment the last call to my_map in renderLeaflet. This is the return value of the function and if you dont call it, nothing will happen.

library(shiny)
library(leaflet)

data = data.frame(
  lng = runif(100,15,16),
  lat = runif(100,45,50)
)

ui <- fluidPage(
  leafletOutput("map")
)

server <- function(input, output, session) {
  output$map <- renderLeaflet({
    my_map <- leaflet(data)
    my_map <- addTiles(map =  my_map)
    for (i in 1:3) {
      my_map <- addCircleMarkers(map = my_map, lat = ~lat, lng = ~lng)
      my_map <- addCircleMarkers(map = my_map, lat = ~lat * i/10, lng = ~lng * i/10, color ="red")
      my_map <- addCircleMarkers(map = my_map, lat = ~lat * i/30, lng = ~lng * i/30, color ="green")
    }

    ## Uncomment the next line, to see whats happening.
    my_map
  })
}

shinyApp(ui, server)