simDSM {AHMbook} | R Documentation |

## Simulate line transect data for density surface modeling

### Description

The function generates a population represented as a binomial point pattern in a heterogeneous landscape with density a function of the covariate Habitat. Data for multiple line transect surveys using a wiggly transect are then simulated, and the pixel IDs for the activity centers of detected individuals returned.

To recreate the data sets used in the book with R 3.6.0 or later, include `sample.kind="Rounding"`

in the call to `set.seed`

. This should only be used for reproduction of old results.

### Usage

```
simDSM(X, Ntotal = 400, sigma = 0.65, beta1 = 1.0,
nsurveys = 2, xlim = c(-0.5, 3.5), ylim = c(-0.5, 4.5), show.plots = TRUE)
```

### Arguments

`X` |
a 2-column matrix with coordinates of regularly spaced points along the transect line; see Examples. |

`Ntotal` |
the true total number of individuals in the study area. |

`sigma` |
scale parameter for the half-normal detection function. |

`beta1` |
coefficient for the relationship between the Habitat covariate and population density. |

`nsurveys` |
the number of replicate surveys along the transect. |

`xlim` , `ylim` |
the extent of the (rectangular) study area |

`show.plots` |
if TRUE, summary plots are displayed. |

### Value

A list with the values of the input arguments and the following additional elements:

`Habitat` |
a vector for the habitat covariate for each pixel |

`Habgrid` |
a 2-column matrix with the coordinates of center of each pixel |

`nPix` |
the number of pixels in the study area |

`N` |
true number of activity centers in each pixel |

`U` |
a 2-column matrix with the locations of ACs for all individuals in the population |

`Ucap` |
a 2-column matrix with the locations of ACs for individuals detected at least once |

`nind` |
the number of individuals detected at least once |

`pixel` |
a nind x nsurvey matrix with the pixel ID for the activity center or NA if the individual was not detected on the survey |

### Author(s)

Marc Kéry, Andy Royle & Mike Meredith

### References

Kéry, M. & Royle, J.A. (2021) *Applied Hierarchical Modeling in Ecology* AHM2 - 11.10.

### Examples

```
# Run the function with default values and look at the output
library(AHMbook)
data(wigglyLine)
points <- sp::SpatialPoints( wigglyLine )
sLine <- sp::Line(points)
regpoints <- sp::spsample(sLine, 100, type = "regular")
str(simDSM(X = regpoints@coords))
# Generate the data set used in AHM2 11.10
RNGversion("3.5.3")
set.seed(2027, kind = "Mersenne-Twister")
tmp <- simDSM(X = regpoints@coords) # Produces Fig 11.15 in the book
```

*AHMbook*version 0.2.9 Index]