Retrieve coordinate reference system from sf or sfc object
Set or replace retrieve coordinate reference system from object
st_crs(x, ...) # S3 method for sf st_crs(x, ...) # S3 method for numeric st_crs(x, ...) # S3 method for character st_crs(x, ...) # S3 method for sfc st_crs(x, ..., parameters = FALSE) # S3 method for bbox st_crs(x, ...) # S3 method for CRS st_crs(x, ...) # S3 method for crs st_crs(x, ...) st_crs(x) <- value # S3 method for sf st_crs(x) <- value # S3 method for sfc st_crs(x) <- value st_set_crs(x, value) NA_crs_ # S3 method for crs is.na(x) # S3 method for crs $(x, name) # S3 method for crs format(x, ...) st_axis_order(authority_compliant = logical(0))
| x | |
|---|---|
| ... | ignored |
| parameters | logical; |
| value | one of (i) character: a string accepted by GDAL, (ii) integer, a valid EPSG value (numeric), or (iii) an object of class |
| name | element name |
| authority_compliant | logical; specify whether axis order should be handled compliant to the authority; if omitted, the current value is printed. |
An object of class crs of length 2.
If x is numeric, return crs object for EPSG:x;
if x is character, return crs object for x;
if x is of class sf or sfc, return its crs object.
Object of class crs, which is a list with elements input (length-1 character)
and wkt (length-1 character).
Elements may be NA valued; if all elements are NA the CRS is missing valued, and coordinates are
assumed to relate to an arbitrary Cartesian coordinate system.
st_axis_order returns the (logical) current value, invisibly if it is
being set.
The *crs functions create, get, set or replace the crs attribute
of a simple feature geometry list-column. This attribute is of class crs,
and is a list consisting of input (user input, e.g. "EPSG:4326" or "WGS84"
or a proj4string), and wkt, an automatically generated wkt representation of the crs.
Comparison of two objects of class crs uses the GDAL function
OGRSpatialReference::IsSame.
In case a coordinate reference system is replaced, no transformation takes place and a warning is raised to stress this.
NA_crs_ is the crs object with missing values for input and wkt.
the $ method for crs objects retrieves named elements
using the GDAL interface; named elements include
"SemiMajor", "SemiMinor", "InvFlattening", "IsGeographic",
"units_gdal", "IsVertical", "WktPretty", "Wkt",
"Name", "proj4string", "epsg", "yx" and
"ud_unit" (this may be subject to changes in future GDAL versions).
format.crs returns NA if the crs is missing valued, or else the name of a crs if it is different from "unknown", or else the user input if it was set, or else its "proj4string" representation;
st_axis_order can be used to get and set the axis order: TRUE
indicates axes order according to the authority
(e.g. EPSG:4326 defining coordinates to be latitude,longitude pairs), FALSE
indicates the usual GIS (display) order (longitude,latitude). This can be useful
when data are read, or have to be written, with coordinates in authority compliant order.
The return value is the current state of this (FALSE, by default).
sfc = st_sfc(st_point(c(0,0)), st_point(c(1,1))) sf = st_sf(a = 1:2, geom = sfc) st_crs(sf) = 4326 st_geometry(sf)#> Geometry set for 2 features #> geometry type: POINT #> dimension: XY #> bbox: xmin: 0 ymin: 0 xmax: 1 ymax: 1 #> CRS: EPSG:4326#>#>#> Geometry set for 2 features #> geometry type: POINT #> dimension: XY #> bbox: xmin: 0 ymin: 0 xmax: 1 ymax: 1 #> CRS: EPSG:4326#>#>sfc = st_sfc(st_point(c(0,0)), st_point(c(1,1))) library(dplyr) x = sfc %>% st_set_crs(4326) %>% st_transform(3857) x#> Geometry set for 2 features #> geometry type: POINT #> dimension: XY #> bbox: xmin: 0 ymin: -7.081155e-10 xmax: 111319.5 ymax: 111325.1 #> CRS: EPSG:3857#>#>st_crs("EPSG:3857")$input#> [1] "EPSG:3857"st_crs(3857)$proj4string#> [1] "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"st_crs(3857)$b # numeric#> [1] 6378137st_crs(3857)$units # character#> [1] "m"pt = st_sfc(st_point(c(0, 60)), crs = 4326) # st_axis_order() only has effect in GDAL >= 2.5.0: st_axis_order() # query default: FALSE means interpret pt as (longitude latitude)#> [1] FALSE#>(old_value = st_axis_order(TRUE))#> [1] FALSE# now interpret pt as (latitude longitude), as EPSG:4326 prescribes: st_axis_order() # query current value#> [1] TRUE#>st_axis_order(old_value) # set back to old value