Read shapefiles from many folders

Question

I have shapefiles spread over many folders and I'd like to pull them out and run a script to process each one in the same way. All the .shp files have the same name and I need to folder name to come along as an id (haven't attempted that part yet). I am stuck on the first step, but I feel like I am close.

# Read folder names to get list of folders

    folders <- list.dirs(path = "./locs", full.names = TRUE, recursive = TRUE)

# Make function that reads inside a folder same way for all files
  
    all_files <- function(folder) {
    readOGR(dsn = folder, layer = "SAMENAME.shp", verbose = FALSE)
}

# Map the function to each folder listed in "folders".

    try <- map(folders, all_files)

Sorry I don't have a reprex for this, maybe I can build one tomorrow if I can get some traction here.

Answer 1

I think you are pretty close. I think you just need three fixes 1) use a paste0() function to combine the folder name and the shapefile name in the "dsn" argument, 2) add a return() call in your all_files() function and 3) switch from map() to either do.call() or lapply(). Try tweaking your code like this:

# Read folder names to get list of folders

    folders <- list.dirs(path = "./locs", full.names = TRUE, recursive = TRUE)

# Make function that reads inside a folder same way for all files
  
    all_files <- function(folder) {
    out<-readOGR(dsn = paste0(folder, "SAMENAME.shp", sep+"/), layer = "SAMENAME.shp", verbose = FALSE)
    return(out)
}

# Map the function to each folder listed in "folders".

    try <- lapply(folders, all_files) #lapply() approach
    try2 <- do.call(all_files, folders) #do.call() approach

If that doesn't work, you could consider reading in the shapefiles using the sf::read_st() function