
Read simple features from IGN Web Feature Service (WFS) from location and name of layer.
get_wfs(x = NULL,
layer = NULL,
filename = NULL,
spatial_filter = "bbox",
ecql_filter = NULL,
overwrite = FALSE,
interactive = FALSE)
sf
object from sf
package or NULL
if no data.
Object of class sf
or sfc
. Needs to be located in
France.
character
; name of the layer from get_layers_metadata("wfs")
or directly from
IGN website
character
;Either a string naming a file or a connection open
for writing. (ex : "test.shp" or "~/test.shp")
character
; spatial predicate from ECQL language.
See detail and examples for more info.
character
; corresponding to an ECQL query.
See detail and examples for more info.
logical
; if TRUE, file is overwrite.
character
; if TRUE, no need to specify layer
, you'll be ask.
get_wfs
use ECQL language : a query language created by the OpenGeospatial Consortium.
It provide multiple spatial filter : "intersects", "disjoint", "contains", "within", "touches",
"crosses", "overlaps", "equals", "relate", "beyond", "dwithin". For "relate", "beyond",
"dwithin", argument can be provide using vector like :
spatial_filter = c("dwithin", distance, units). More info about ECQL language
here.
ECQL query can be provided to ecql_filter
. This allows direct query of the IGN's WFS
geoservers. If x
is set, then the ecql_filter
comes in addition to the
spatial_filter
. More info for writing ECQL
here
get_layers_metadata()
if (FALSE) {
library(sf)
library(tmap)
# Shape from the best town in France
penmarch <- read_sf(system.file("extdata/penmarch.shp", package = "happign"))
# For quick testing, use interactive = TRUE
shape <- get_wfs(x = penmarch,
interactive = TRUE)
## Getting borders of best town in France
metadata_table <- get_layers_metadata("wfs", "administratif")
layer <- metadata_table[32,1] # LIMITES_ADMINISTRATIVES_EXPRESS.LATEST:commune
# Downloading borders
borders <- get_wfs(penmarch, layer)
# Plotting result
qtm(borders, fill = NULL, borders = "firebrick") # easy map
# Get forest_area of the best town in France
forest_area <- get_wfs(x = borders,
layer = "LANDCOVER.FORESTINVENTORY.V1:resu_bdv1_shape")
qtm(forest_area, fill = "nom_typn")
# Using ECQL filters to query IGN server
## First find attributes of the layer
attrs <- get_wfs_attributes(layer)
## e.g. : find all commune's name starting by "plou"
plou_borders <- get_wfs(x = NULL, # When x is NULL, all France is query
layer = "LIMITES_ADMINISTRATIVES_EXPRESS.LATEST:commune",
ecql_filter = "nom_m LIKE 'PLOU%'")
qtm(plou_borders)
## Combining ecql_filters
plou_borders_inf_2000 <- get_wfs(x = NULL, # When x is NULL, all France is query
layer = "LIMITES_ADMINISTRATIVES_EXPRESS.LATEST:commune",
ecql_filter = "nom_m LIKE 'PLOU%' AND population < 2000")
qtm(plou_borders)+ qtm(plou_borders_inf_2000, fill = "red")
}
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