How to iterate erasing multiple vectors from another vector using R?

Question

I need to erase different vector layers(shapefiles) using R, but I am not sure how to do it in a fast way.

I have 10 different shapefiles and a basemap (also shapefile) that I need to erase my vectors from (I need something equivalent to using the "difference" tool in QGIS).

I know how to do it manually, using the ms_erase tool, but I was wondering if there is an easy way of iterating this process:

output1 <- ms_erase(basemap, vector1)
output2 <- ms_erase(output1 , vector2)
output3 <- ms_erase(output2 , vector3)

I loaded the vectors using the st_read function, so their class in R is data.frame.

Answer 1

I would read your 10 shapefiles into a list object so that you can easily combine them using do.call.

s <- do.call("rbind", lapply(list.files(getwd(), "shp$")[-1], st_read))

Note; if s does not result in an sf object you may have to wrap it in st_as_sf. The index "[-1]" is a illustration of removing a specific file. I am assuming that your "basemap" is in the same directory so, it should not be read into the list. You can figure out the position(s) of shapefiles to omit by just looking at the results of list.files(getwd(), "shp$"). Using indexing you can read in specific files eg., [c(1,3,5)] would read in the first, third and fifth files in the list.files vector.

Once you have the features that you want erased, then read in the base map and difference the features (not tested).

st_erase <- function(x, y) { st_difference(x, st_union(st_combine(y))) }
  b <- st_read(list.files(getwd(), "shp$")[1])
    e <- st_erase(b, s)