# set_projection

From tmaptools v1.0
by Martijn Tennekes

##### Set and get the map projection

The function `set_projection`

sets the projection of a shape file. It is
a convenient wrapper of `spTransform`

and
`projectRaster`

with shortcuts for commonly
used projections. The projection can also be set directly in the plot call
with `tm_shape`

. This function is also used to set the current
projection information if this is missing. The function `get_projection`

is used to get the projection information.

##### Usage

```
set_projection(shp, projection = NA, current.projection = NA, overwrite.current.projection = FALSE)
get_projection(shp, as.CRS = FALSE, guess.longlat = FALSE)
```

##### Arguments

- shp
- shape object of class
`Spatial`

,`Raster`

, or`sf`

(see details). - projection
- new projection. See
`get_proj4`

for options. This argument is only used to transform the`shp`

. Use`current.projection`

to specify the current projection of`shp`

. - current.projection
- the current projection of
`shp`

. See`get_proj4`

for possible options. Only use this if the current projection is missing or wrong. - overwrite.current.projection
- logical that determines whether the current projection is overwritten if it already has a projection that is different.
- as.CRS
- should a CRS object be returned instead of a PROJ.4 character string? Default is
`FALSE`

. - guess.longlat
- if
`TRUE`

, it checks if the coordinates are within -180/180 and -90/90, and if so, it returns the WGS84 longlat projection (which is`get_proj4("longlat")`

).

##### Details

For raster objects, the projection method is based on the type of data. For numeric layers, the bilinear method is used, and for categorical layers the nearest neighbor. See `projectRaster`

for details.

##### Value

`set_projection`

returns a (transformed) shape object with updated projection information. `get_projection`

returns the `PROJ.4`

character string of `shp`

.
*Documentation reproduced from package tmaptools, version 1.0, License: GPL-3*

### Community examples

Looks like there are no examples yet.