R/CleanLines.R

In cesarkero/IterativeSteinerTree: Calculates Steiner Tree with Iterative processes (parallel...not yet...)

#' Clean lines (SpatialLinesDataFrame) for Steiner tree
#'
#' @param x SpatialLinesDataFrame (network)
#'
#' @description This function will remove unchained parts of the lines layer
#' that can cause issues when executing v.net.steiner. After removing those parts,
#' the layer is imported into grass to execute v.clean and v.build to repare
#' topology issues#'
#' @return SLDF ready to use in v.net and v.net.steiner
#' @export
#'
#' @examples
#' \dontrun{
#' setGRASS(gisBase = "/usr/lib/grass78", epsg= 25829)
#' data("l")
#' lc <- CleanLines(l[1:100,])
#' mapview(l[1:100,])+lc
#' }
CleanLines <- function(x){
    # CRITICAL PART IN ORDER TO MAKE V.NET.STEINER

    # MiniBuffer, Merge, Singleparts and Unselect Lines out of the main network
    lx <- st_cast(st_union(st_buffer(st_as_sf(x),0.1)),"POLYGON")
    NotMainNet <- st_union(lx[st_area(lx)!=max(st_area(lx)),])
    xpart <- st_intersects(st_as_sf(x), NotMainNet, sparse = FALSE)

    # remove lines that intersect with any of the tiny buffers from NotMainNet
    ls <- x[!xpart[,1],]

    #import lines
    writeVECT(ls, 'lx', v.in.ogr_flags = c('o','overwrite','quiet'))

    # clean
    execGRASS("v.clean", input = 'lx', output = 'lc', tool = c('break','snap'),
              threshold = c(5,5), flags = c('c','overwrite','quiet'))
    #build
    execGRASS("v.build", map = 'lc', option = 'build', flags = c('e', 'overwrite', 'quiet'))

    return(readVECT('lc'))
}