# project

##### Projection of coordinates

Projection of lat/long coordinates or its inverse.

- Keywords
- spatial

##### Usage

```
project(xy, proj, inverse = FALSE, degrees = TRUE, silent = FALSE,
ellps.default="sphere")
```

##### Arguments

- xy
input (list, matrix or 2d-array) - see details below.

- proj
projection definition

- inverse
if

`TRUE`

inverse projection is performed (from a cartographic projection into lat/long), otherwise projects from lat/long into a cartographic projection.- degrees
if

`TRUE`

then the lat/long data is assumed to be in degrees, otherwise in radians- silent
if set to

`TRUE`

, warnings will be suppressed- ellps.default
default ellipsoid that will be added if no datum or ellipsoid parameter is specified in

`proj`

. Older versions of PROJ.4 didn't require a datum (and used sphere by default), but 4.5.0 and higher always require a datum or an ellipsoid. Set to`NA`

if no datum should be added to`proj`

(e.g. if you specify an ellipsoid directly).

##### Details

The input can be a list of two or more vectors (if the list contains
more than two entries, only first two entries are used and a warning
is issued), a two-dimensional matrix or array (the number of columns
or rows must be exactly two) or a vector of the length 2. For a 2x2
input the columns are taken as `x`

and `y`

. If the input
is a list then the result will be a list with the entries named
`x`

and `y`

, otherwise the result is a matrix with two
columns.

When the list form is used, inputs are recycled with a warning when necessary.

`proj`

specifies the target (or source if inverse)
projection. The format can be either a single (unnamed) string which
contains all parameters:
`"+proj=lcc +lat_1=33 +lat_2=45 +lat_0=39 +lon_0=-96"`

or an unnamed vector of complete individual parameters:
`c("+proj=lcc","+lat_1=33","+lat_2=45","+lat_0=39","+lon_0=-96")`

or a named vector or list that will be composed into parameters:
`list(proj="lcc", lat_1=33, lat_2=45, lat_0=39, lon_0=-96)`

if `degrees`

is `TRUE`

then the latitude and longitude are
expected to be in degrees, if `FALSE`

then in radians.

##### Value

A two column matrix or list of coordinates. If the input was a list then the output will be a list, otherwise a matrix.

##### References

##### Examples

```
# NOT RUN {
## this is just very simple, because we don't want to depend on
## maps package, so we can't show more useful stuff..
data(state)
s <- project(state.center, "+proj=merc")
plot(s, type='n', asp=1)
text(s,, state.abb)
# }
```

*Documentation reproduced from package proj4, version 1.0-10.1, License: GPL-2*