Load multiple shapefiles Shiny r - r

Question

I am trying to load shapefiles in shiny r based on a selection users make in selectInput. This is easy to do when the user can only select one shapefile. However when the user can select multiple shapefiles it becomes trickier. I am looking for a way to avoir having to write several times addPolygons(data = input$input_company[1] %>% addPolygons(data = input$input_company[2] %>% addPolygons(data = input$input_company[3] and so on.
Here is my attempt: writing a loop in server :
# Working directory ------------------------------------------------------------
wd <- "~/path/"
# Read multiple shapefiles with standardised name ------------------------------
items <- c("item_1", "item_2", "item_3")
for (sp in items) {
files.sp <- readOGR(dsn = wd, layer = sp,
verbose = FALSE)
assign(sp, files.sp)
}
# UI ---------------------------------------------------------------------------
ui <- navbarPage(
title = "Here my Title",
id="nav",
theme = shinytheme("flatly"),
mainPanel("Interactive map",
div(class="outer",
tags$head(
includeCSS("styles.css")),
leafletOutput("m", width="100%", height="100%"),
absolutePanel(
id = "hist_panel", class = "panel panel-default",
fixed = TRUE, draggable = TRUE,
top = 100, left = "auto", right = 0,
bottom = "auto",
width = "27%", height = "auto"),
absolutePanel(
id = "hist_panel", class = "panel panel-default",
fixed = FALSE, draggable = TRUE,
top = 100, left = "auto", right = 0,
bottom = "auto",
width = "27%", height = "auto",
selectInput(inputId = "input_items", label = "Items",
choices = c("Item 1" = "item_1", "Item 2" = "item_2", "Item 3" = "item_3"),
multiple = TRUE,
selected = "item_1")),
)
)
)
# Server -----------------------------------------------------------------------
server <- function(input, output, session) {
output$m <- renderLeaflet({
for (i in 1:length(input$input_items)) {
sp <- input$input_items[i]
tmp <- get(sp)
m <- leaflet() %>%
# Add Basemap OSM
addTiles(group = "OSM (default)") %>%
addPolygons(data = get(tmp))
}
}
)
}
# Run shiny app on laptop
shinyApp(ui, server)
What I am trying to avoid is this (because I may have 100+ items to display, and also because if the user selects less than 3 items I get an error message...):
# Server -----------------------------------------------------------------------
server <- function(input, output, session) {
output$m <- renderLeaflet({
m <- leaflet() %>%
# Add Basemap OSM
addTiles(group = "OSM (default)") %>%
addPolygons(data = input$input_items[1]) %>%
addPolygons(data = input$input_items[2]) %>%
addPolygons(data = input$input_items[3])
}
)
}
Thank you!

Answer 1

Here is a solution
First merge shapefiles together
shp <- bind(item_1, item_2, item_3)
Then in server side:
# Server -----------------------------------------------------------------------
server <- function(input, output, session) {
observeEvent(input$input_items,{
sel_shp <- shp[shp#data$id %in% input$input_items, ]
output$m <- renderLeaflet({
m <- leaflet() %>%
# Add Basemap OSM
addTiles(group = "OSM (default)") %>%
addPolygons(data = sel_shp)
})
})
}