Allow user to upload a shapefile in shiny - r

Question

I am making a shiny app that allows the user to upload a shapefile using the sf package. When I select the .shp file via the Browse window, I get an error. How can I allow the user to upload a shapefile, that then get it read by st_read' or readOGR. And, I don't know why st_read is going to C:\Users\Ed\AppData... as this is not location of the shapefile.
library(shiny)
library(shinydahsboard)
library(sf)
UI
ui = navbarPage("Project Eddy", theme = shinytheme("sandstone"),
tabPanel("Location",
sidebarLayout(sidebarPanel(fileInput("shp", "Please choose a Shapefile",
multiple = F,
".shp")),
mainPanel(plotlyOutput(outputId = "Area")))))
Server
server = function(input, output, session) {
myshp.df = reactive({
# input$shp will be NULL initially. After the user selects
# and uploads a file, head of that data file by default,
# or all rows if selected, will be shown.
req(input$shp)
df = st_read(dsn = input$shp$datapath,
quite = T)
if(input$disp == "head") {
return(head(df))
}
else {
return(df)
}
})
output$Area = renderPlotly({
req(myshp.df())
a = myshp.df
c = leaflet(a) %>%
addPolygons(stroke = FALSE, fillOpacity = 0.5, smoothFactor = 0.5) %>%
addProviderTiles('Esri.WorldImagery')
})
})
Error
Warning in CPL_read_ogr(dsn, layer, query, as.character(options), quiet, :
GDAL Error 4: Unable to open C:\Users\Ed\AppData\Local\Temp\RtmpioUU3m\b0cd5b1eb5c4fe4219e6c114\0.shx or C:\Users\Ed\AppData\Local\Temp\RtmpioUU3m\b0cd5b1eb5c4fe4219e6c114\0.SHX. Set SHAPE_RESTORE_SHX config option to YES to restore or create it.
Warning: Error in : Cannot open "C:\Users\Ed\AppData\Local\Temp\RtmpioUU3m\b0cd5b1eb5c4fe4219e6c114\0.shp"; The source could be corrupt or not supported. See `st_drivers()` for a list of supported formats.
128:

Answer 1

ESRI shapefiles are known troublemakers, as they live over multiple files - the single *.shp file is not enough for your shiny app to work with.
Consider a solution proposed by user fiorepalombina on RStudio Community forum: https://community.rstudio.com/t/shinyfiles-and-shapefiles/89099

Answer 2

To read-in a shapefile, the user must submit at minimum the mandatory files (.shp, .shx and .dbf). Once files are uploaded, you can access the location and name via $datapath and $name.
By default, shiny names file inputs like this:
C:\Users\DWISME~1\AppData\Local\Temp\17\RtmpiOjVGv/6903ae29a41daccceee4b8a5/0.dbf
C:\Users\DWISME~1\AppData\Local\Temp\17\RtmpiOjVGv/6903ae29a41daccceee4b8a5/1.prj
C:\Users\DWISME~1\AppData\Local\Temp\17\RtmpiOjVGv/6903ae29a41daccceee4b8a5/2.sbn
C:\Users\DWISME~1\AppData\Local\Temp\17\RtmpiOjVGv/6903ae29a41daccceee4b8a5/3.sbx
C:\Users\DWISME~1\AppData\Local\Temp\17\RtmpiOjVGv/6903ae29a41daccceee4b8a5/4.shp
C:\Users\DWISME~1\AppData\Local\Temp\17\RtmpiOjVGv/6903ae29a41daccceee4b8a5/5.shx
My approach is to create a function that accesses the file input location and change the directory:
library(shiny)
library(sf)
library(purrr)
ui <- fluidPage(
br(),
fluidRow(column(6, offset = 3,
fileInput("shp", label = "Input Shapfile (.shp,.dbf,.sbn,.sbx,.shx,.prj)",
width = "100%",
accept = c(".shp",".dbf",".sbn",".sbx",".shx",".prj"), multiple=TRUE))),
br(),
fluidRow(column(8, offset = 2,
p("input$shp$datapath" , style = "font-weight: bold"),
verbatimTextOutput("shp_location", placeholder = T))),
br(),
fluidRow(column(8, offset = 2,
p("input$shp$name" , style = "font-weight: bold"),
verbatimTextOutput("shp_name", placeholder = T)))
)
server <- function(input, output, session) {
# Read-in shapefile function
Read_Shapefile <- function(shp_path) {
infiles <- shp_path$datapath # get the location of files
dir <- unique(dirname(infiles)) # get the directory
outfiles <- file.path(dir, shp_path$name) # create new path name
name <- strsplit(shp_path$name[1], "\\.")[[1]][1] # strip name
purrr::walk2(infiles, outfiles, ~file.rename(.x, .y)) # rename files
x <- read_sf(file.path(dir, paste0(name, ".shp"))) # read-in shapefile
return(x)
}
# Read-shapefile once user submits files
observeEvent(input$shp, {
user_shp <- Read_Shapefile(input$shp)
plot(user_shp) # plot to R console
# Print original file path location and file name to UI
output$shp_location <- renderPrint({
full_path <- strsplit(input$shp$datapath," ")
purrr::walk(full_path, ~cat(.x, "\n"))
})
output$shp_name <- renderPrint({
name_split <- strsplit(input$shp$name," ")
purrr::walk(name_split, ~cat(.x, "\n"))
})
})
}
shinyApp(ui, server)