R/get_parks_osm.R
In ecological-cities/home2park: Spatial Provision of Urban Parks
Defines functions
get_parks_osm
Documented in
get_parks_osm
#'Get public parks from OpenStreetMap
#'
#'Download and process OpenStreetMap (OSM) park polygons within a specified geographical `place`,
#'from the [Geofabrik database](https://download.geofabrik.de). It is a wrapper around
#'functions in the package [`osmextract`](https://docs.ropensci.org/osmextract/index.html), and
#'processes the downloaded files for subsequent analyses. Refer to package `osmextract` for
#'more details and options for input arguments when downloading the data.
#'
#'OSM polygons are filtered by key-value attributes, where `leisure:` is `park`, `garden` or `nature_reserve`,
#'and `access:` is not `no` or `private`, as well as the key-value pair `tourism:zoo`.
#'If `mutually_exclusive_with` is provided, [intersections](https://postgis.net/docs/ST_Intersection.html) between
#'the output and these polygon(s) will be excluded using `polygons_mutually_exclude()`.
#'Polygons are then cleaned up using `polygons_clean()`.
#'
#'@param place `sf` object (with projected coordinate reference system). Geographical area to match with the (`.osm.pbf`) file in the data archive.
#'Argument passed to `osmextract::oe_match()`.
#'@param date Date of OSM data snapshot to download. Object of class "Date" in format `%Y-%m-%d`. Refer to https://download.geofabrik.de
#'for the specific dates available. Defaults to `NULL` (download the latest available data).
#'@param mutually_exclusive_with list of `sf` object(s). This may be used to
#'ensure that polygons (e.g. parks, beaches, informal nature areas) are mutually-exclusive (i.e. non-overlapping).
#'Remove output polygons [contained](https://postgis.net/docs/ST_Contains.html) within, as well as [intersections](https://postgis.net/docs/ST_Intersection.html) between,
#'each element of this list. Should have the same coordinate reference system as `place`.
#'@param snap_tolerance numeric. Argument for `tolerance` level passed to `sf::st_snap()`,
#'used to rectify nearly coincident edges between polygons before processing (e.g. `sf::st_contains()`, `sf::st_covers()`).
#'Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system.
#'Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
#'@param min_area numeric. Specify minimum area of each polygon to be retained in the output,
#'passed to argument `threshold` in `smoothr::drop_crumbs()`.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m^2.
#'@param aggregate_polygons numeric. Argument for `dist` passed to `sf::st_buffer()`.
#'Buffered polygons that overlap will be aggregated into multipolygons.
#'Set to `NULL` if you do not wish to aggregate to multipolygons.
#'@param dir_raw character. Directory to download the raw unprocessed OSM data. Passed to
#'argument `download_directory` in `osmextract::oe_read()`.
#'@param filename character (optional). File path to export output data (GeoJSON format).
#'@param ... Other arguments passed to `osmextract::oe_read()`.
#'
#'@return The processed park polygons (`sf` object).
#'
#'@import sf
#'@import checkmate
#'@import osmextract
#'@importFrom dplyr filter mutate
#'@importFrom units set_units
#'@importFrom smoothr fill_holes drop_crumbs
#'@importFrom rlang .data
#'
#'@examples
#' \dontrun{
#' data(pop_sgp)
#' pop_sgp <- sf::st_transform(pop_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # merge all census blocks for chosen year (2020) into single multi-polygon
#' # function requires that polygons are merged
#' city_boundaries <- pop_sgp %>%
#' dplyr::filter(year == 2020) %>%
#' sf::st_union() %>%
#' sf::st_as_sf() %>%
#' smoothr::fill_holes(threshold = units::set_units(1, 'km^2')) %>% # clean up
#' smoothr::drop_crumbs(threshold = units::set_units(1, 'km^2')) %>%
#' sf::st_make_valid()
#'
#' # run function
#' get_parks_osm(place = city_boundaries,
#' date = as.Date('2021-01-01'),
#' snap_tolerance = 5,
#' aggregate_polygons = 15,
#' filename = 'public-parks_osm-polygons_2021-01-01.geojson')
#' }
#'
#'@export
get_parks_osm <- function(place, date = NULL, mutually_exclusive_with = list(), snap_tolerance = 5,
min_area = units::set_units(0, "m^2"), aggregate_polygons = 15, dir_raw = osmextract::oe_download_directory(),
filename = NULL, ...) {
# Error checking ------------------
coll <- checkmate::makeAssertCollection()
# data type
checkmate::assert_date(date, any.missing = FALSE, all.missing = FALSE, len = 1, null.ok = TRUE,
add = coll)
checkmate::assert_list(mutually_exclusive_with, any.missing = FALSE, all.missing = TRUE,
unique = TRUE, null.ok = FALSE, add = coll)
# file paths
checkmate::assert_character(filename, min.len = 1, any.missing = FALSE, all.missing = FALSE,
null.ok = TRUE, add = coll)
# all crs similar
if (length(mutually_exclusive_with) != 0) {
checkmate::assertTRUE(all(unlist(lapply(lapply(mutually_exclusive_with, sf::st_crs), function(x) x ==
sf::st_crs(place)))))
}
checkmate::reportAssertions(coll)
# Calculations ------------------
# form url link ----
link <- osmextract::oe_match(place, provider = "geofabrik")$url # download region
if (!is.null(date)) {
date <- format(date, "%y%m%d")
link <- gsub("latest", date, link) # change download date if provided
}
# parameters to filter data after download ----
osmkeys <- c("access") # leisure & tourism already default keys
q <- "SELECT * FROM 'multipolygons' WHERE (leisure IN ('park', 'garden', 'nature_reserve') AND (access IS NULL OR access NOT IN ('no', 'private'))) OR tourism = 'zoo'"
# to extract features that intersect bounding box (geographic crs)
bb <- sf::st_transform(place, sf::st_crs(4326)) %>%
sf::st_geometry() %>%
sf::st_as_text()
# download and filter data ---- filter by st_read() instead of using
# vectortranslate_option
results <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = q, wkt_filter = bb)
# transform back to same crs as 'place', then remove empty geoms, cast to individual
# polygons
suppressWarnings(results <- results %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# run helper functions ----
if (length(mutually_exclusive_with) != 0) {
for (i in seq_along(mutually_exclusive_with)) {
results <- polygons_mutually_exclude(input = results, mutually_exclude = mutually_exclusive_with[[i]],
snap_tolerance = snap_tolerance)
}
}
results <- polygons_clean(results, snap_tolerance = snap_tolerance, min_area = min_area,
aggregate_polygons = aggregate_polygons)
# export ----
if (!is.null(filename)) {
sf::st_write(results, filename, driver = "GeoJSON", delete_dsn = TRUE, overwrite = TRUE)
}
rm(link, osmkeys, q, bb)
return(results)
}
#'Get public beaches from OpenStreetMap
#'
#'Download and process OpenStreetMap (OSM) beach polygons within a specified geographical `place`,
#'from the [Geofabrik database](https://download.geofabrik.de). It is a wrapper around
#'functions in the package [`osmextract`](https://docs.ropensci.org/osmextract/index.html), and
#'processes the downloaded files for subsequent analyses. Refer to package `osmextract` for
#'more details and options for input arguments when downloading the data.
#'
#'OSM polygons are filtered by key-value attributes, where `natural:beach`, and `access:` is not `no` or `private`.
#'If `mutually_exclusive_with` is provided, [intersections](https://postgis.net/docs/ST_Intersection.html) between
#'the output and these polygon(s) will be excluded using `polygons_mutually_exclude()`.
#'Polygons are then cleaned up using `polygons_clean()`.
#'
#'@param place `sf` object (with projected coordinate reference system). Geographical area to match with the (`.osm.pbf`) file in the data archive.
#'Argument passed to `osmextract::oe_match()`.
#'@param date Date of OSM data snapshot to download. Object of class "Date" in format `%Y-%m-%d`. Refer to https://download.geofabrik.de
#'for the specific dates available. Defaults to `NULL` (download the latest available data).
#'@param mutually_exclusive_with list of `sf` object(s). This may be used to
#'ensure that polygons (e.g. parks, beaches, informal nature areas) are mutually-exclusive (i.e. non-overlapping).
#'Remove output polygons [contained](https://postgis.net/docs/ST_Contains.html) within, as well as [intersections](https://postgis.net/docs/ST_Intersection.html) between,
#'each element of this list. Should have the same coordinate reference system as `place`.
#'@param snap_tolerance numeric. Argument for `tolerance` level passed to `sf::st_snap()`,
#'used to rectify nearly coincident edges between polygons before processing (e.g. `sf::st_contains()`, `sf::st_covers()`).
#'Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system.
#'Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
#'@param min_area numeric. Specify minimum area of each polygon to be retained in the output,
#'passed to argument `threshold` in `smoothr::drop_crumbs()`.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m^2.
#'@param aggregate_polygons numeric. Argument for `dist` passed to `sf::st_buffer()`.
#'Buffered polygons that overlap will be aggregated into multipolygons.
#'Set to `NULL` if you do not wish to aggregate to multipolygons.
#'@param dir_raw character. Directory to download the raw unprocessed OSM data. Passed to
#'argument `download_directory` in `osmextract::oe_read()`.
#'@param filename character (optional). File path to export output data (GeoJSON format).
#'@param ... Other arguments passed to `osmextract::oe_read()`.
#'
#'@return The processed beach polygons (`sf` object).
#'
#'@import sf
#'@import checkmate
#'@import osmextract
#'@importFrom dplyr filter mutate
#'@importFrom units set_units
#'@importFrom smoothr fill_holes drop_crumbs
#'@importFrom rlang .data
#'
#'@examples
#' \dontrun{
#' data(pop_sgp)
#' pop_sgp <- sf::st_transform(pop_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # merge all census blocks for chosen year (2020) into single multi-polygon
#' # function requires that polygons are merged
#' city_boundaries <- pop_sgp %>%
#' dplyr::filter(year == 2020) %>%
#' sf::st_union() %>%
#' sf::st_as_sf() %>%
#' smoothr::fill_holes(threshold = units::set_units(1, 'km^2')) %>% # clean up
#' smoothr::drop_crumbs(threshold = units::set_units(1, 'km^2')) %>%
#' sf::st_make_valid()
#'
#' data(parks_sgp) # to exclude beaches within/intersecting these polygons
#' parks_sgp <- sf::st_transform(parks_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # run function
#' get_beaches_osm(place = city_boundaries,
#' date = as.Date('2021-01-01'),
#' mutually_exclusive_with = list(parks_sgp),
#' snap_tolerance = 5,
#' aggregate_polygons = 15,
#' filename = 'public-beaches_osm-polygons_2021-01-01.geojson')
#' }
#'
#'@export
get_beaches_osm <- function(place, date = NULL, mutually_exclusive_with = list(), snap_tolerance = 5,
min_area = units::set_units(0, "m^2"), aggregate_polygons = 15, dir_raw = osmextract::oe_download_directory(),
filename = NULL, ...) {
# Error checking ------------------
coll <- checkmate::makeAssertCollection()
# data type
checkmate::assert_date(date, any.missing = FALSE, all.missing = FALSE, len = 1, null.ok = TRUE,
add = coll)
checkmate::assert_list(mutually_exclusive_with, any.missing = FALSE, all.missing = TRUE,
unique = TRUE, null.ok = FALSE, add = coll)
# file paths
checkmate::assert_character(filename, min.len = 1, any.missing = FALSE, all.missing = FALSE,
null.ok = TRUE, add = coll)
# all crs similar
if (length(mutually_exclusive_with) != 0) {
checkmate::assertTRUE(all(unlist(lapply(lapply(mutually_exclusive_with, sf::st_crs), function(x) x ==
sf::st_crs(place)))))
}
checkmate::reportAssertions(coll)
# Calculations ------------------
# form url link ----
link <- osmextract::oe_match(place, provider = "geofabrik")$url # download region
if (!is.null(date)) {
date <- format(date, "%y%m%d")
link <- gsub("latest", date, link) # change download date if provided
}
# parameters to filter data after download ----
osmkeys <- c("access") # 'natural' already a default key
q <- "SELECT * FROM 'multipolygons' WHERE natural = 'beach' AND (access IS NULL OR access NOT IN ('no', 'private'))"
# to extract features that intersect bounding box (geographic crs)
bb <- sf::st_transform(place, sf::st_crs(4326)) %>%
sf::st_geometry() %>%
sf::st_as_text()
# download and filter data ---- filter by st_read() instead of using
# vectortranslate_option
results <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = q, wkt_filter = bb)
# transform back to same crs as 'place', then remove empty geoms, cast to individual
# polygons
suppressWarnings(results <- results %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# run helper functions ----
if (length(mutually_exclusive_with) != 0) {
for (i in seq_along(mutually_exclusive_with)) {
results <- polygons_mutually_exclude(input = results, mutually_exclude = mutually_exclusive_with[[i]],
snap_tolerance = snap_tolerance)
}
}
results <- polygons_clean(results, snap_tolerance = snap_tolerance, min_area = min_area,
aggregate_polygons = aggregate_polygons)
# export ----
if (!is.null(filename)) {
sf::st_write(results, filename, driver = "GeoJSON", delete_dsn = TRUE, overwrite = TRUE)
}
rm(link, osmkeys, q, bb)
return(results)
}
#'Get informal nature areas from OpenStreetMap
#'
#'Download and process OpenStreetMap (OSM) 'informal nature' polygons within a specified geographical `place`,
#'from the [Geofabrik database](https://download.geofabrik.de). It is a wrapper around
#'functions in the package [`osmextract`](https://docs.ropensci.org/osmextract/index.html), and
#'processes the downloaded files for subsequent analyses. Refer to package `osmextract` for
#'more details and options for input arguments when downloading the data.
#'
#'OSM polygons are filtered by key-value attributes, where `landuse:` is `forest` or `meadow`,
#'or `natural:` is `wood`, `scrub`, `heath`, `grassland`, `wetland`, `marsh`, `fell` or `tundra`,
#'and `access:` is not `no`, `private` or `restricted`.
#'Polygons [contained](https://postgis.net/docs/ST_Contains.html) within `leisure:golf_course` are excluded after mutually-[snapping](https://postgis.net/docs/ST_Snap.html) vertices between the two
#'(see argument `snap_tolerance`). [Intersections](https://postgis.net/docs/ST_Intersection.html) with `landuse:military` polygons are also removed.
#'To exclude nature areas that are inaccessible, OSM trail lines are extracted (`highway:` is `track`, `path`, `footway` or `cycleway`,
#'and `access:` is not `no` or `private`). The remaining polygons without such trails [within](https://postgis.net/docs/ST_Within.html) their boundaries are removed.
#'If `mutually_exclusive_with` is provided, [intersections](https://postgis.net/docs/ST_Intersection.html) between
#'the output and these polygon(s) will be excluded using `polygons_mutually_exclude()`.
#'Polygons are then cleaned up using `polygons_clean()`.
#'
#'@param place `sf` object (with projected coordinate reference system). Geographical area to match with the (`.osm.pbf`) file in the data archive.
#'Argument passed to `osmextract::oe_match()`.
#'@param date Date of OSM data snapshot to download. Object of class "Date" in format `%Y-%m-%d`. Refer to https://download.geofabrik.de
#'for the specific dates available. Defaults to `NULL` (download the latest available data).
#'@param mutually_exclusive_with list of `sf` object(s). This may be used to
#'ensure that polygons (e.g. parks, beaches, informal nature areas) are mutually-exclusive (i.e. non-overlapping).
#'Remove output polygons [contained](https://postgis.net/docs/ST_Contains.html) within, as well as [intersections](https://postgis.net/docs/ST_Intersection.html) between,
#'each element of this list. Should have the same coordinate reference system as `place`.
#'@param snap_tolerance numeric. Argument for `tolerance` level passed to `sf::st_snap()`,
#'used to rectify nearly coincident edges between polygons before processing (e.g. `sf::st_contains()`, `sf::st_covers()`).
#'Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system.
#'Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
#'@param min_area numeric. Specify minimum area of each polygon to be retained in the output,
#'passed to argument `threshold` in `smoothr::drop_crumbs()`.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m^2.
#'@param min_trails numeric. Specify minimum length of OSM trail lines that has to be within
#'nature area polygons, for the polygons to be retained in the output.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m.
#'@param aggregate_polygons numeric. Argument for `dist` passed to `sf::st_buffer()`.
#'Buffered polygons that overlap will be aggregated into multipolygons.
#'Set to `NULL` if you do not wish to aggregate to multipolygons.
#'@param dir_raw character. Directory to download the raw unprocessed OSM data. Passed to
#'argument `download_directory` in `osmextract::oe_read()`.
#'@param filename character (optional). File path to export output data (GeoJSON format).
#'@param ... Other arguments passed to `osmextract::oe_read()`.
#'
#'@return The processed 'informal nature areas' (polygons) that are publicly accessible (`sf` object).
#'
#'@import sf
#'@import checkmate
#'@import osmextract
#'@importFrom dplyr filter mutate group_by summarise left_join
#'@importFrom units set_units
#'@importFrom smoothr fill_holes drop_crumbs
#'@importFrom rlang .data
#'
#'@examples
#' \dontrun{
#' data(pop_sgp)
#' pop_sgp <- sf::st_transform(pop_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # merge all census blocks for chosen year (2020) into single multi-polygon
#' # function requires that polygons are merged
#' city_boundaries <- pop_sgp %>%
#' dplyr::filter(year == 2020) %>%
#' sf::st_union() %>%
#' sf::st_as_sf() %>%
#' smoothr::fill_holes(threshold = units::set_units(1, 'km^2')) %>% # clean up
#' smoothr::drop_crumbs(threshold = units::set_units(1, 'km^2')) %>%
#' sf::st_make_valid()
#'
#' data(parks_sgp) # to exclude nature areas within/intersecting these polygons
#' parks_sgp <- sf::st_transform(parks_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # run function
#' get_informalnature_osm(place = city_boundaries,
#' date = as.Date('2021-01-01'),
#' mutually_exclusive_with = list(parks_sgp),
#' snap_tolerance = 5,
#' min_area = units::set_units(2500, 'm^2'),
#' min_trails = units::set_units(0, 'm'),
#' aggregate_polygons = 15,
#' filename = 'nature-areas_osm-polygons_2021-01-01.geojson')
#' }
#'
#'@export
get_informalnature_osm <- function(place, date = NULL, mutually_exclusive_with = list(), snap_tolerance = 5,
min_area = units::set_units(0, "m^2"), min_trails = units::set_units(0, "m"), aggregate_polygons = 15,
dir_raw = osmextract::oe_download_directory(), filename = NULL, ...) {
# Error checking ------------------
coll <- checkmate::makeAssertCollection()
# data type
checkmate::assert_date(date, any.missing = FALSE, all.missing = FALSE, len = 1, null.ok = TRUE,
add = coll)
checkmate::assert_list(mutually_exclusive_with, any.missing = FALSE, all.missing = TRUE,
unique = TRUE, null.ok = FALSE, add = coll)
# file paths
checkmate::assert_character(filename, min.len = 1, any.missing = FALSE, all.missing = FALSE,
null.ok = TRUE, add = coll)
# all crs similar
if (length(mutually_exclusive_with) != 0) {
checkmate::assertTRUE(all(unlist(lapply(lapply(mutually_exclusive_with, sf::st_crs), function(x) x ==
sf::st_crs(place)))))
}
checkmate::reportAssertions(coll)
# Calculations ------------------
# form url link ----
link <- osmextract::oe_match(place, provider = "geofabrik")$url # download region
if (!is.null(date)) {
date <- format(date, "%y%m%d")
link <- gsub("latest", date, link) # change download date if provided
}
# parameters to filter data after download ----
osmkeys <- c("access") # 'landuse' & 'natural' already a default keys
q <- "SELECT * FROM 'multipolygons' WHERE (landuse IN ('forest', 'meadow') OR natural IN ('wood', 'scrub', 'heath', 'grassland', 'wetland', 'marsh', 'fell', 'tundra')) AND (access IS NULL OR access NOT IN ('no', 'private', 'restricted'))"
# to extract features that intersect bounding box (geographic crs)
bb <- sf::st_transform(place, sf::st_crs(4326)) %>%
sf::st_geometry() %>%
sf::st_as_text()
# download and filter data ---- filter by st_read() instead of using
# vectortranslate_option
results <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = q, wkt_filter = bb)
# transform back to same crs as 'place', then remove empty geoms, cast to individual
# polygons
suppressWarnings(results <- results %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# exclude golf courses ----
golf <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = "SELECT * FROM 'multipolygons' WHERE leisure = 'golf_course'",
wkt_filter = bb)
suppressWarnings(golf <- golf %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# rectify minor overlaps w mutual snap, BUT SAVE TO NEW VAR
golf2 <- st_snap(golf, results, tolerance = snap_tolerance)
results2 <- st_snap(results, golf2, tolerance = snap_tolerance)
# exclude entire polygon if contained within golf course (USE EDITED results2 variable)
results <- results %>%
dplyr::mutate(id = row_number()) %>%
dplyr::filter(!(.data$id %in% unlist(st_contains(golf2, results2 %>%
mutate(id = row_number()))))) %>%
dplyr::select(-.data$id) %>%
st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON")
rm(results2, golf, golf2)
# exclude military areas ----
military <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = "SELECT * FROM 'multipolygons' WHERE landuse = 'military'",
wkt_filter = bb)
suppressWarnings(military <- military %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# rectify minor overlaps w mutual snap
military <- st_snap(military, results, tolerance = snap_tolerance)
results <- st_snap(results, military, tolerance = snap_tolerance)
# exclude intersection between the 2 polygons
military <- military %>%
st_union() %>%
st_make_valid()
results <- st_difference(results, military) %>%
st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON")
rm(military)
# exclude polygons with no public trails ----
trails <- osmextract::oe_read(link, download_directory = dir_raw, layer = "lines", extra_tags = c("access"),
force_vectortranslate = TRUE, query = "SELECT * FROM 'lines' WHERE (highway IN ('track', 'path', 'footway', 'cycleway')) AND (access IS NULL OR access NOT IN ('no', 'private'))",
wkt_filter = bb)
suppressWarnings(trails <- trails %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid())
results <- results %>%
dplyr::mutate(id = row_number()) %>%
dplyr::filter((.data$id %in% unlist(st_within(trails, results %>%
mutate(id = row_number())))))
# exclude nature areas below min trail length
trails <- st_intersection(trails, results) # subset trails
trails$length <- st_length(trails) # new col for line length
trails <- trails %>%
dplyr::group_by(.data$id) %>%
dplyr::summarise(trails = sum(.data$length, na.rm = TRUE))
st_geometry(trails) <- NULL
results <- results %>%
dplyr::left_join(trails, by = "id")
results$trails[is.na(results$trails)] <- 0 # replace na with 0
results <- results %>%
dplyr::filter(!.data$trails < min_trails)
rm(trails)
# run helper functions ----
if (length(mutually_exclusive_with) != 0) {
for (i in seq_along(mutually_exclusive_with)) {
results <- polygons_mutually_exclude(input = results, mutually_exclude = mutually_exclusive_with[[i]],
snap_tolerance = snap_tolerance)
}
}
results <- polygons_clean(results, snap_tolerance = snap_tolerance, min_area = min_area,
aggregate_polygons = aggregate_polygons)
# export ----
if (!is.null(filename)) {
sf::st_write(results, filename, driver = "GeoJSON", delete_dsn = TRUE, overwrite = TRUE)
}
rm(link, osmkeys, q, bb)
return(results)
}
ecological-cities/home2park documentation built on Dec. 6, 2023, 1:05 a.m.
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Defines functions get_parks_osm
Documented in get_parks_osm
#'Get public parks from OpenStreetMap
#'
#'Download and process OpenStreetMap (OSM) park polygons within a specified geographical `place`,
#'from the [Geofabrik database](https://download.geofabrik.de). It is a wrapper around
#'functions in the package [`osmextract`](https://docs.ropensci.org/osmextract/index.html), and
#'processes the downloaded files for subsequent analyses. Refer to package `osmextract` for
#'more details and options for input arguments when downloading the data.
#'
#'OSM polygons are filtered by key-value attributes, where `leisure:` is `park`, `garden` or `nature_reserve`,
#'and `access:` is not `no` or `private`, as well as the key-value pair `tourism:zoo`.
#'If `mutually_exclusive_with` is provided, [intersections](https://postgis.net/docs/ST_Intersection.html) between
#'the output and these polygon(s) will be excluded using `polygons_mutually_exclude()`.
#'Polygons are then cleaned up using `polygons_clean()`.
#'
#'@param place `sf` object (with projected coordinate reference system). Geographical area to match with the (`.osm.pbf`) file in the data archive.
#'Argument passed to `osmextract::oe_match()`.
#'@param date Date of OSM data snapshot to download. Object of class "Date" in format `%Y-%m-%d`. Refer to https://download.geofabrik.de
#'for the specific dates available. Defaults to `NULL` (download the latest available data).
#'@param mutually_exclusive_with list of `sf` object(s). This may be used to
#'ensure that polygons (e.g. parks, beaches, informal nature areas) are mutually-exclusive (i.e. non-overlapping).
#'Remove output polygons [contained](https://postgis.net/docs/ST_Contains.html) within, as well as [intersections](https://postgis.net/docs/ST_Intersection.html) between,
#'each element of this list. Should have the same coordinate reference system as `place`.
#'@param snap_tolerance numeric. Argument for `tolerance` level passed to `sf::st_snap()`,
#'used to rectify nearly coincident edges between polygons before processing (e.g. `sf::st_contains()`, `sf::st_covers()`).
#'Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system.
#'Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
#'@param min_area numeric. Specify minimum area of each polygon to be retained in the output,
#'passed to argument `threshold` in `smoothr::drop_crumbs()`.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m^2.
#'@param aggregate_polygons numeric. Argument for `dist` passed to `sf::st_buffer()`.
#'Buffered polygons that overlap will be aggregated into multipolygons.
#'Set to `NULL` if you do not wish to aggregate to multipolygons.
#'@param dir_raw character. Directory to download the raw unprocessed OSM data. Passed to
#'argument `download_directory` in `osmextract::oe_read()`.
#'@param filename character (optional). File path to export output data (GeoJSON format).
#'@param ... Other arguments passed to `osmextract::oe_read()`.
#'
#'@return The processed park polygons (`sf` object).
#'
#'@import sf
#'@import checkmate
#'@import osmextract
#'@importFrom dplyr filter mutate
#'@importFrom units set_units
#'@importFrom smoothr fill_holes drop_crumbs
#'@importFrom rlang .data
#'
#'@examples
#' \dontrun{
#' data(pop_sgp)
#' pop_sgp <- sf::st_transform(pop_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # merge all census blocks for chosen year (2020) into single multi-polygon
#' # function requires that polygons are merged
#' city_boundaries <- pop_sgp %>%
#' dplyr::filter(year == 2020) %>%
#' sf::st_union() %>%
#' sf::st_as_sf() %>%
#' smoothr::fill_holes(threshold = units::set_units(1, 'km^2')) %>% # clean up
#' smoothr::drop_crumbs(threshold = units::set_units(1, 'km^2')) %>%
#' sf::st_make_valid()
#'
#' # run function
#' get_parks_osm(place = city_boundaries,
#' date = as.Date('2021-01-01'),
#' snap_tolerance = 5,
#' aggregate_polygons = 15,
#' filename = 'public-parks_osm-polygons_2021-01-01.geojson')
#' }
#'
#'@export
get_parks_osm <- function(place, date = NULL, mutually_exclusive_with = list(), snap_tolerance = 5,
min_area = units::set_units(0, "m^2"), aggregate_polygons = 15, dir_raw = osmextract::oe_download_directory(),
filename = NULL, ...) {
# Error checking ------------------
coll <- checkmate::makeAssertCollection()
# data type
checkmate::assert_date(date, any.missing = FALSE, all.missing = FALSE, len = 1, null.ok = TRUE,
add = coll)
checkmate::assert_list(mutually_exclusive_with, any.missing = FALSE, all.missing = TRUE,
unique = TRUE, null.ok = FALSE, add = coll)
# file paths
checkmate::assert_character(filename, min.len = 1, any.missing = FALSE, all.missing = FALSE,
null.ok = TRUE, add = coll)
# all crs similar
if (length(mutually_exclusive_with) != 0) {
checkmate::assertTRUE(all(unlist(lapply(lapply(mutually_exclusive_with, sf::st_crs), function(x) x ==
sf::st_crs(place)))))
}
checkmate::reportAssertions(coll)
# Calculations ------------------
# form url link ----
link <- osmextract::oe_match(place, provider = "geofabrik")$url # download region
if (!is.null(date)) {
date <- format(date, "%y%m%d")
link <- gsub("latest", date, link) # change download date if provided
}
# parameters to filter data after download ----
osmkeys <- c("access") # leisure & tourism already default keys
q <- "SELECT * FROM 'multipolygons' WHERE (leisure IN ('park', 'garden', 'nature_reserve') AND (access IS NULL OR access NOT IN ('no', 'private'))) OR tourism = 'zoo'"
# to extract features that intersect bounding box (geographic crs)
bb <- sf::st_transform(place, sf::st_crs(4326)) %>%
sf::st_geometry() %>%
sf::st_as_text()
# download and filter data ---- filter by st_read() instead of using
# vectortranslate_option
results <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = q, wkt_filter = bb)
# transform back to same crs as 'place', then remove empty geoms, cast to individual
# polygons
suppressWarnings(results <- results %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# run helper functions ----
if (length(mutually_exclusive_with) != 0) {
for (i in seq_along(mutually_exclusive_with)) {
results <- polygons_mutually_exclude(input = results, mutually_exclude = mutually_exclusive_with[[i]],
snap_tolerance = snap_tolerance)
}
}
results <- polygons_clean(results, snap_tolerance = snap_tolerance, min_area = min_area,
aggregate_polygons = aggregate_polygons)
# export ----
if (!is.null(filename)) {
sf::st_write(results, filename, driver = "GeoJSON", delete_dsn = TRUE, overwrite = TRUE)
}
rm(link, osmkeys, q, bb)
return(results)
}
#'Get public beaches from OpenStreetMap
#'
#'Download and process OpenStreetMap (OSM) beach polygons within a specified geographical `place`,
#'from the [Geofabrik database](https://download.geofabrik.de). It is a wrapper around
#'functions in the package [`osmextract`](https://docs.ropensci.org/osmextract/index.html), and
#'processes the downloaded files for subsequent analyses. Refer to package `osmextract` for
#'more details and options for input arguments when downloading the data.
#'
#'OSM polygons are filtered by key-value attributes, where `natural:beach`, and `access:` is not `no` or `private`.
#'If `mutually_exclusive_with` is provided, [intersections](https://postgis.net/docs/ST_Intersection.html) between
#'the output and these polygon(s) will be excluded using `polygons_mutually_exclude()`.
#'Polygons are then cleaned up using `polygons_clean()`.
#'
#'@param place `sf` object (with projected coordinate reference system). Geographical area to match with the (`.osm.pbf`) file in the data archive.
#'Argument passed to `osmextract::oe_match()`.
#'@param date Date of OSM data snapshot to download. Object of class "Date" in format `%Y-%m-%d`. Refer to https://download.geofabrik.de
#'for the specific dates available. Defaults to `NULL` (download the latest available data).
#'@param mutually_exclusive_with list of `sf` object(s). This may be used to
#'ensure that polygons (e.g. parks, beaches, informal nature areas) are mutually-exclusive (i.e. non-overlapping).
#'Remove output polygons [contained](https://postgis.net/docs/ST_Contains.html) within, as well as [intersections](https://postgis.net/docs/ST_Intersection.html) between,
#'each element of this list. Should have the same coordinate reference system as `place`.
#'@param snap_tolerance numeric. Argument for `tolerance` level passed to `sf::st_snap()`,
#'used to rectify nearly coincident edges between polygons before processing (e.g. `sf::st_contains()`, `sf::st_covers()`).
#'Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system.
#'Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
#'@param min_area numeric. Specify minimum area of each polygon to be retained in the output,
#'passed to argument `threshold` in `smoothr::drop_crumbs()`.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m^2.
#'@param aggregate_polygons numeric. Argument for `dist` passed to `sf::st_buffer()`.
#'Buffered polygons that overlap will be aggregated into multipolygons.
#'Set to `NULL` if you do not wish to aggregate to multipolygons.
#'@param dir_raw character. Directory to download the raw unprocessed OSM data. Passed to
#'argument `download_directory` in `osmextract::oe_read()`.
#'@param filename character (optional). File path to export output data (GeoJSON format).
#'@param ... Other arguments passed to `osmextract::oe_read()`.
#'
#'@return The processed beach polygons (`sf` object).
#'
#'@import sf
#'@import checkmate
#'@import osmextract
#'@importFrom dplyr filter mutate
#'@importFrom units set_units
#'@importFrom smoothr fill_holes drop_crumbs
#'@importFrom rlang .data
#'
#'@examples
#' \dontrun{
#' data(pop_sgp)
#' pop_sgp <- sf::st_transform(pop_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # merge all census blocks for chosen year (2020) into single multi-polygon
#' # function requires that polygons are merged
#' city_boundaries <- pop_sgp %>%
#' dplyr::filter(year == 2020) %>%
#' sf::st_union() %>%
#' sf::st_as_sf() %>%
#' smoothr::fill_holes(threshold = units::set_units(1, 'km^2')) %>% # clean up
#' smoothr::drop_crumbs(threshold = units::set_units(1, 'km^2')) %>%
#' sf::st_make_valid()
#'
#' data(parks_sgp) # to exclude beaches within/intersecting these polygons
#' parks_sgp <- sf::st_transform(parks_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # run function
#' get_beaches_osm(place = city_boundaries,
#' date = as.Date('2021-01-01'),
#' mutually_exclusive_with = list(parks_sgp),
#' snap_tolerance = 5,
#' aggregate_polygons = 15,
#' filename = 'public-beaches_osm-polygons_2021-01-01.geojson')
#' }
#'
#'@export
get_beaches_osm <- function(place, date = NULL, mutually_exclusive_with = list(), snap_tolerance = 5,
min_area = units::set_units(0, "m^2"), aggregate_polygons = 15, dir_raw = osmextract::oe_download_directory(),
filename = NULL, ...) {
# Error checking ------------------
coll <- checkmate::makeAssertCollection()
# data type
checkmate::assert_date(date, any.missing = FALSE, all.missing = FALSE, len = 1, null.ok = TRUE,
add = coll)
checkmate::assert_list(mutually_exclusive_with, any.missing = FALSE, all.missing = TRUE,
unique = TRUE, null.ok = FALSE, add = coll)
# file paths
checkmate::assert_character(filename, min.len = 1, any.missing = FALSE, all.missing = FALSE,
null.ok = TRUE, add = coll)
# all crs similar
if (length(mutually_exclusive_with) != 0) {
checkmate::assertTRUE(all(unlist(lapply(lapply(mutually_exclusive_with, sf::st_crs), function(x) x ==
sf::st_crs(place)))))
}
checkmate::reportAssertions(coll)
# Calculations ------------------
# form url link ----
link <- osmextract::oe_match(place, provider = "geofabrik")$url # download region
if (!is.null(date)) {
date <- format(date, "%y%m%d")
link <- gsub("latest", date, link) # change download date if provided
}
# parameters to filter data after download ----
osmkeys <- c("access") # 'natural' already a default key
q <- "SELECT * FROM 'multipolygons' WHERE natural = 'beach' AND (access IS NULL OR access NOT IN ('no', 'private'))"
# to extract features that intersect bounding box (geographic crs)
bb <- sf::st_transform(place, sf::st_crs(4326)) %>%
sf::st_geometry() %>%
sf::st_as_text()
# download and filter data ---- filter by st_read() instead of using
# vectortranslate_option
results <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = q, wkt_filter = bb)
# transform back to same crs as 'place', then remove empty geoms, cast to individual
# polygons
suppressWarnings(results <- results %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# run helper functions ----
if (length(mutually_exclusive_with) != 0) {
for (i in seq_along(mutually_exclusive_with)) {
results <- polygons_mutually_exclude(input = results, mutually_exclude = mutually_exclusive_with[[i]],
snap_tolerance = snap_tolerance)
}
}
results <- polygons_clean(results, snap_tolerance = snap_tolerance, min_area = min_area,
aggregate_polygons = aggregate_polygons)
# export ----
if (!is.null(filename)) {
sf::st_write(results, filename, driver = "GeoJSON", delete_dsn = TRUE, overwrite = TRUE)
}
rm(link, osmkeys, q, bb)
return(results)
}
#'Get informal nature areas from OpenStreetMap
#'
#'Download and process OpenStreetMap (OSM) 'informal nature' polygons within a specified geographical `place`,
#'from the [Geofabrik database](https://download.geofabrik.de). It is a wrapper around
#'functions in the package [`osmextract`](https://docs.ropensci.org/osmextract/index.html), and
#'processes the downloaded files for subsequent analyses. Refer to package `osmextract` for
#'more details and options for input arguments when downloading the data.
#'
#'OSM polygons are filtered by key-value attributes, where `landuse:` is `forest` or `meadow`,
#'or `natural:` is `wood`, `scrub`, `heath`, `grassland`, `wetland`, `marsh`, `fell` or `tundra`,
#'and `access:` is not `no`, `private` or `restricted`.
#'Polygons [contained](https://postgis.net/docs/ST_Contains.html) within `leisure:golf_course` are excluded after mutually-[snapping](https://postgis.net/docs/ST_Snap.html) vertices between the two
#'(see argument `snap_tolerance`). [Intersections](https://postgis.net/docs/ST_Intersection.html) with `landuse:military` polygons are also removed.
#'To exclude nature areas that are inaccessible, OSM trail lines are extracted (`highway:` is `track`, `path`, `footway` or `cycleway`,
#'and `access:` is not `no` or `private`). The remaining polygons without such trails [within](https://postgis.net/docs/ST_Within.html) their boundaries are removed.
#'If `mutually_exclusive_with` is provided, [intersections](https://postgis.net/docs/ST_Intersection.html) between
#'the output and these polygon(s) will be excluded using `polygons_mutually_exclude()`.
#'Polygons are then cleaned up using `polygons_clean()`.
#'
#'@param place `sf` object (with projected coordinate reference system). Geographical area to match with the (`.osm.pbf`) file in the data archive.
#'Argument passed to `osmextract::oe_match()`.
#'@param date Date of OSM data snapshot to download. Object of class "Date" in format `%Y-%m-%d`. Refer to https://download.geofabrik.de
#'for the specific dates available. Defaults to `NULL` (download the latest available data).
#'@param mutually_exclusive_with list of `sf` object(s). This may be used to
#'ensure that polygons (e.g. parks, beaches, informal nature areas) are mutually-exclusive (i.e. non-overlapping).
#'Remove output polygons [contained](https://postgis.net/docs/ST_Contains.html) within, as well as [intersections](https://postgis.net/docs/ST_Intersection.html) between,
#'each element of this list. Should have the same coordinate reference system as `place`.
#'@param snap_tolerance numeric. Argument for `tolerance` level passed to `sf::st_snap()`,
#'used to rectify nearly coincident edges between polygons before processing (e.g. `sf::st_contains()`, `sf::st_covers()`).
#'Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system.
#'Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
#'@param min_area numeric. Specify minimum area of each polygon to be retained in the output,
#'passed to argument `threshold` in `smoothr::drop_crumbs()`.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m^2.
#'@param min_trails numeric. Specify minimum length of OSM trail lines that has to be within
#'nature area polygons, for the polygons to be retained in the output.
#'Provided either as a units object (see `units::set_units()`), or a number in the units of
#'the coordinate reference system. Defaults to `0` m.
#'@param aggregate_polygons numeric. Argument for `dist` passed to `sf::st_buffer()`.
#'Buffered polygons that overlap will be aggregated into multipolygons.
#'Set to `NULL` if you do not wish to aggregate to multipolygons.
#'@param dir_raw character. Directory to download the raw unprocessed OSM data. Passed to
#'argument `download_directory` in `osmextract::oe_read()`.
#'@param filename character (optional). File path to export output data (GeoJSON format).
#'@param ... Other arguments passed to `osmextract::oe_read()`.
#'
#'@return The processed 'informal nature areas' (polygons) that are publicly accessible (`sf` object).
#'
#'@import sf
#'@import checkmate
#'@import osmextract
#'@importFrom dplyr filter mutate group_by summarise left_join
#'@importFrom units set_units
#'@importFrom smoothr fill_holes drop_crumbs
#'@importFrom rlang .data
#'
#'@examples
#' \dontrun{
#' data(pop_sgp)
#' pop_sgp <- sf::st_transform(pop_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # merge all census blocks for chosen year (2020) into single multi-polygon
#' # function requires that polygons are merged
#' city_boundaries <- pop_sgp %>%
#' dplyr::filter(year == 2020) %>%
#' sf::st_union() %>%
#' sf::st_as_sf() %>%
#' smoothr::fill_holes(threshold = units::set_units(1, 'km^2')) %>% # clean up
#' smoothr::drop_crumbs(threshold = units::set_units(1, 'km^2')) %>%
#' sf::st_make_valid()
#'
#' data(parks_sgp) # to exclude nature areas within/intersecting these polygons
#' parks_sgp <- sf::st_transform(parks_sgp, sf::st_crs(32648)) # transform to projected crs
#'
#' # run function
#' get_informalnature_osm(place = city_boundaries,
#' date = as.Date('2021-01-01'),
#' mutually_exclusive_with = list(parks_sgp),
#' snap_tolerance = 5,
#' min_area = units::set_units(2500, 'm^2'),
#' min_trails = units::set_units(0, 'm'),
#' aggregate_polygons = 15,
#' filename = 'nature-areas_osm-polygons_2021-01-01.geojson')
#' }
#'
#'@export
get_informalnature_osm <- function(place, date = NULL, mutually_exclusive_with = list(), snap_tolerance = 5,
min_area = units::set_units(0, "m^2"), min_trails = units::set_units(0, "m"), aggregate_polygons = 15,
dir_raw = osmextract::oe_download_directory(), filename = NULL, ...) {
# Error checking ------------------
coll <- checkmate::makeAssertCollection()
# data type
checkmate::assert_date(date, any.missing = FALSE, all.missing = FALSE, len = 1, null.ok = TRUE,
add = coll)
checkmate::assert_list(mutually_exclusive_with, any.missing = FALSE, all.missing = TRUE,
unique = TRUE, null.ok = FALSE, add = coll)
# file paths
checkmate::assert_character(filename, min.len = 1, any.missing = FALSE, all.missing = FALSE,
null.ok = TRUE, add = coll)
# all crs similar
if (length(mutually_exclusive_with) != 0) {
checkmate::assertTRUE(all(unlist(lapply(lapply(mutually_exclusive_with, sf::st_crs), function(x) x ==
sf::st_crs(place)))))
}
checkmate::reportAssertions(coll)
# Calculations ------------------
# form url link ----
link <- osmextract::oe_match(place, provider = "geofabrik")$url # download region
if (!is.null(date)) {
date <- format(date, "%y%m%d")
link <- gsub("latest", date, link) # change download date if provided
}
# parameters to filter data after download ----
osmkeys <- c("access") # 'landuse' & 'natural' already a default keys
q <- "SELECT * FROM 'multipolygons' WHERE (landuse IN ('forest', 'meadow') OR natural IN ('wood', 'scrub', 'heath', 'grassland', 'wetland', 'marsh', 'fell', 'tundra')) AND (access IS NULL OR access NOT IN ('no', 'private', 'restricted'))"
# to extract features that intersect bounding box (geographic crs)
bb <- sf::st_transform(place, sf::st_crs(4326)) %>%
sf::st_geometry() %>%
sf::st_as_text()
# download and filter data ---- filter by st_read() instead of using
# vectortranslate_option
results <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = q, wkt_filter = bb)
# transform back to same crs as 'place', then remove empty geoms, cast to individual
# polygons
suppressWarnings(results <- results %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# exclude golf courses ----
golf <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = "SELECT * FROM 'multipolygons' WHERE leisure = 'golf_course'",
wkt_filter = bb)
suppressWarnings(golf <- golf %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# rectify minor overlaps w mutual snap, BUT SAVE TO NEW VAR
golf2 <- st_snap(golf, results, tolerance = snap_tolerance)
results2 <- st_snap(results, golf2, tolerance = snap_tolerance)
# exclude entire polygon if contained within golf course (USE EDITED results2 variable)
results <- results %>%
dplyr::mutate(id = row_number()) %>%
dplyr::filter(!(.data$id %in% unlist(st_contains(golf2, results2 %>%
mutate(id = row_number()))))) %>%
dplyr::select(-.data$id) %>%
st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON")
rm(results2, golf, golf2)
# exclude military areas ----
military <- osmextract::oe_read(link, download_directory = dir_raw, layer = "multipolygons",
extra_tags = osmkeys, force_vectortranslate = TRUE, query = "SELECT * FROM 'multipolygons' WHERE landuse = 'military'",
wkt_filter = bb)
suppressWarnings(military <- military %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON"))
# rectify minor overlaps w mutual snap
military <- st_snap(military, results, tolerance = snap_tolerance)
results <- st_snap(results, military, tolerance = snap_tolerance)
# exclude intersection between the 2 polygons
military <- military %>%
st_union() %>%
st_make_valid()
results <- st_difference(results, military) %>%
st_make_valid() %>%
st_cast("MULTIPOLYGON") %>%
st_cast("POLYGON")
rm(military)
# exclude polygons with no public trails ----
trails <- osmextract::oe_read(link, download_directory = dir_raw, layer = "lines", extra_tags = c("access"),
force_vectortranslate = TRUE, query = "SELECT * FROM 'lines' WHERE (highway IN ('track', 'path', 'footway', 'cycleway')) AND (access IS NULL OR access NOT IN ('no', 'private'))",
wkt_filter = bb)
suppressWarnings(trails <- trails %>%
dplyr::filter(!sf::st_is_empty(.)) %>%
sf::st_transform(sf::st_crs(place)) %>%
sf::st_make_valid())
results <- results %>%
dplyr::mutate(id = row_number()) %>%
dplyr::filter((.data$id %in% unlist(st_within(trails, results %>%
mutate(id = row_number())))))
# exclude nature areas below min trail length
trails <- st_intersection(trails, results) # subset trails
trails$length <- st_length(trails) # new col for line length
trails <- trails %>%
dplyr::group_by(.data$id) %>%
dplyr::summarise(trails = sum(.data$length, na.rm = TRUE))
st_geometry(trails) <- NULL
results <- results %>%
dplyr::left_join(trails, by = "id")
results$trails[is.na(results$trails)] <- 0 # replace na with 0
results <- results %>%
dplyr::filter(!.data$trails < min_trails)
rm(trails)
# run helper functions ----
if (length(mutually_exclusive_with) != 0) {
for (i in seq_along(mutually_exclusive_with)) {
results <- polygons_mutually_exclude(input = results, mutually_exclude = mutually_exclusive_with[[i]],
snap_tolerance = snap_tolerance)
}
}
results <- polygons_clean(results, snap_tolerance = snap_tolerance, min_area = min_area,
aggregate_polygons = aggregate_polygons)
# export ----
if (!is.null(filename)) {
sf::st_write(results, filename, driver = "GeoJSON", delete_dsn = TRUE, overwrite = TRUE)
}
rm(link, osmkeys, q, bb)
return(results)
}
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