Test whether a SpatRaster or SpatVector has a longitude/latitude coordinate reference system (CRS), or perhaps has one. That is, when the CRS is unknown (`""`

) but the x coordinates are within -181 and 181 and the y coordinates are within -90.1 and 90.1. For a SpatRaster you can also test if it has a longitude/latitude CRS and it is "global" (covers all longitudes).

A warning is given if the CRS is missing or if it is specified as longitude/latitude but the coordinates do not match that.

```
# S4 method for SpatRaster
is.lonlat(x, perhaps=FALSE, warn=TRUE, global=FALSE)
# S4 method for SpatVector
is.lonlat(x, perhaps=FALSE, warn=TRUE)
# S4 method for character
is.lonlat(x, perhaps=FALSE, warn=TRUE)
```

## Arguments

- x
SpatRaster or SpatVector

- perhaps
logical. If `TRUE`

and the CRS is unknown, the method returns `TRUE`

if the coordinates are plausible for longitude/latitude

- warn
logical. If `TRUE`

, a warning is given if the CRS is unknown but assumed to be lon/lat and `perhaps=TRUE`

- global
logical. If `TRUE`

, the method tests if the raster covers all longitudes (from -180 to 180 degrees) such that the extreme columns are in fact adjacent

## Examples

```
r <- rast()
is.lonlat(r)
#> [1] TRUE
is.lonlat(r, global=TRUE)
#> [1] TRUE
crs(r) <- ""
is.lonlat(r)
#> Warning: [is.lonlat] unknown crs
#> [1] NA
is.lonlat(r, perhaps=TRUE, warn=FALSE)
#> [1] TRUE
crs(r) <- "+proj=lcc +lat_1=48 +lat_2=33 +lon_0=-100 +ellps=WGS84"
is.lonlat(r)
#> [1] FALSE
```