Description Usage Arguments Details Value References Examples

Minor functions.

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`xy` |
2-column matrix or dataframe |

`xy1` |
2-column matrix or dataframe |

`xy2` |
2-column matrix or dataframe |

`mask` |
mask or linearmask object |

`sessnum` |
integer; for multi-session masks, the number of the session |

`inf` |
numeric value to use for +infinity |

`...` |
other arguments for |

`getmeanSD`

is used by `make.mask`

to standardize
mask coordinates.

For `masklength`

the input should be a linear mask from secrlinear.

`edist`

computes the Euclidean distance between each point in xy1
and each point in xy2. (This duplicates the functionality of ‘rdist’
in package fields).

`nedist`

computes the non-Euclidean distance between each point
in xy1 and each point in xy2, in two dimensions. The calculation uses
gdistance (van Etten 2014; see also Csardi \& Nepusz 2006): a
transition layer is formed representing the connections between
adjacent points in `mask`

. By default, points within a 16-point
neighbourhood are considered ‘adjacent’. Distances are obtained by
Dijkstra's (1959) algorithm as least cost paths through the graph of
all points in the mask.

`nedist`

has some subtle options. If ‘mask’ is missing then the
transition layer will be formed from ‘xy2’. If ‘mask’ has a covariate
named ‘noneuc’ then this will be used to weight distances. The ...
argument of `nedist`

allows the user to vary arguments of
`transition`

(defaults transitionFunction =
mean and directions = 16). Be warned this can lead to unexpected
results! Point pairs that are completely separated receive the
distance +Inf unless a finite value is provided for the argument
‘inf’. See
secr-noneuclidean.pdf
for uses of `nedist`

.

For `getMeanSD`

, a dataframe with columns ‘x’ and ‘y’ and two
rows, mean and SD.

For `maskarea`

, the summed area of mask cells in hectares (ha).

For `masklength`

, the summed length of mask cells in kilometers (km).

For `edist`

and `nedist`

, a matrix with dim = c(nrow(xy1), nrow(xy2)).

Dijkstra, E. W. (1959) A note on two problems in connexion with
graphs. *Numerische Mathematik*, **1**, 269–271.

Csardi, G. and Nepusz, T. (2006) The igraph software package for complex
network research. *InterJournal*, **1695**. http://igraph.org.

van Etten, J. (2014) gdistance: distances and routes on geographical grids. R package version 1.1-5. http://CRAN.R-project.org/package=gdistance

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secr documentation built on Sept. 20, 2017, 5:02 p.m.

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