# projection: Projection In ctmm: Continuous-Time Movement Modeling

## Description

Functions to manipulate the coordinate reference system (CRS) of ctmm objects

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25``` ```## S4 method for signature 'telemetry' projection(x,asText=TRUE) ## S4 method for signature 'ctmm' projection(x,asText=TRUE) ## S4 method for signature 'UD' projection(x,asText=TRUE) ## S4 method for signature 'list' projection(x,asText=TRUE) ## S4 method for signature 'NULL' projection(x,asText=TRUE) ## S4 replacement method for signature 'telemetry' projection(x) <- value ## S4 replacement method for signature 'list' projection(x) <- value ## S3 method for class 'telemetry' median(x,na.rm=FALSE,...) compass(loc=NULL,cex=3,...) ```

## Arguments

 `x` A `telemetry`, `ctmm`, or `UD` object. `asText` If `TRUE`, the projection is returned as text. Otherwise a `CRS` object is returned. `value` Projection to apply. Can also be a data.frame of longitude-latitude foci. `na.rm` Not used. `...` Arguments passed to `Gmedian` or `text`. `loc` Optional two-dimensional coordinates (in meters) at which to draw a north-facing compass needle. `cex` Relative size of compass.

## Details

`projection(x)` returns the projection information from ctmm object `x`, while `projection(x) <- value` applies the projection `value` to object `x`. `median(x)` returns the ellipsoidal geometric median of a telemetry object. `compass(x,y)` plots a north-pointing compass needle at the coordinates (x,y).

## Author(s)

C. H. Fleming

`as.telemetry`.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14``` ```# Load package and data library(ctmm) data(buffalo) # Apply a 1-point projection that preserves North==up projection(buffalo) <- median(buffalo) plot(buffalo) compass() # Apply a 2-point projection safer for elongated disributions projection(buffalo) <- median(buffalo,k=2) # This is the default projection for ctmm plot(buffalo) compass() ```