inst/doc/query-split.R

In osmdata: Import 'OpenStreetMap' Data as Simple Features or Spatial Objects

## ----get-bbox, eval = FALSE---------------------------------------------------
#  library (osmdata)
#  
#  bb <- getbb ("Southeastern Connecticut COG", featuretype = "boundary")
#  bb

## ----out1, eval = FALSE-------------------------------------------------------
#  #>         min       max
#  #> x -72.46677 -71.79315
#  #> y  41.27591  41.75617

## ----bbox-split, eval = FALSE-------------------------------------------------
#  dx <- (bb ["x", "max"] - bb ["x", "min"]) / 2
#  
#  bbs <- list (bb, bb)
#  
#  bbs [[1]] ["x", "max"] <- bb ["x", "max"] - dx
#  bbs [[2]] ["x", "min"] <- bb ["x", "min"] + dx
#  
#  bbs

## ----out2, eval = FALSE-------------------------------------------------------
#  #> [[1]]
#  #>         min       max
#  #> x -72.46677 -72.12996
#  #> y  41.27591  41.75617
#  #>
#  #> [[2]]
#  #>         min       max
#  #> x -72.12996 -71.79315
#  #> y  41.27591  41.75617

## ----opq-2x, eval = FALSE-----------------------------------------------------
#  res <- list ()
#  
#  res [[1]] <- opq (bbox = bbs [[1]]) |>
#      add_osm_feature (key = "admin_level", value = "8") |>
#      osmdata_sf ()
#  res [[2]] <- opq (bbox = bbs [[2]]) |>
#      add_osm_feature (key = "admin_level", value = "8") |>
#      osmdata_sf ()

## ----opq-merge, eval = FALSE--------------------------------------------------
#  res <- c (res [[1]], res [[2]])

## ----bbox-auto-split, eval = FALSE--------------------------------------------
#  split_bbox <- function (bbox, grid = 2, eps = 0.05) {
#      xmin <- bbox ["x", "min"]
#      ymin <- bbox ["y", "min"]
#      dx <- (bbox ["x", "max"] - bbox ["x", "min"]) / grid
#      dy <- (bbox ["y", "max"] - bbox ["y", "min"]) / grid
#  
#      bboxl <- list ()
#  
#      for (i in 1:grid) {
#          for (j in 1:grid) {
#              b <- matrix (c (
#                  xmin + ((i - 1 - eps) * dx),
#                  ymin + ((j - 1 - eps) * dy),
#                  xmin + ((i + eps) * dx),
#                  ymin + ((j + eps) * dy)
#              ),
#              nrow = 2,
#              dimnames = dimnames (bbox)
#              )
#  
#              bboxl <- append (bboxl, list (b))
#          }
#      }
#      bboxl
#  }

## ----bbox-pre-split, eval = FALSE---------------------------------------------
#  bb <- getbb ("Connecticut", featuretype = NULL)
#  queue <- split_bbox (bb)
#  result <- list ()

## ----auto-query, eval = FALSE-------------------------------------------------
#  while (length (queue) > 0) {
#  
#      print (queue [[1]])
#  
#      opres <- NULL
#      opres <- try ({
#          opq (bbox = queue [[1]], timeout = 25) |>
#              add_osm_feature (key = "natural", value = "tree") |>
#              osmdata_sf ()
#      })
#  
#      if (class (opres) [1] != "try-error") {
#          result <- append (result, list (opres))
#          queue <- queue [-1]
#      } else {
#          bboxnew <- split_bbox (queue [[1]])
#          queue <- append (bboxnew, queue [-1])
#      }
#  }

## ----merge-result-list, eval = FALSE------------------------------------------
#  final <- do.call (c, result)