**Introduction**** **

Circles is a geographical model that uses the location of known occurrences and predicts that a species can be present within a circle with a given radius around these occurrence points. This model does not use the input of environmental variables to predict the distribution of a species.

The radius is by default computed from the mean of all distances between points. This can be a really large distance, for example, if you are modelling marine species that occur across the globe. In this case, some circles might overlap, and the algorithm tries to merge these circles which might result in a failed experiment. The solution is to rerun the experiment with a fixed distance for the radius.

**Advantages**** **

Simple and easy to interpret

Presence only model, no absence data needed

**Limitations**** **

Does not use environmental variables to predict species occurrence

**Assumptions**** **

N/A

**Requirements**** **

No

Configuration options

EcoCommons allows the user to set model arguments as specified below.

random_seed | There is no impact of setting a random seed for this model. |

Circle radius (d) | The radius of each circle in meters. A single number or a vector with elements corresponding to rows in p. If missing, the diameter is computed from the mean inter-point distance. (default = NULL) |

Tails (tails) | The "tails” argument can be used to ignore the left or right tail of the percentile distribution for a variable. I If supplied, tails should be a character vector with a length equal to the number of variables used in the model. Valid values are "both", "low" and "high". (default = NULL) |

References

Hijmans, R. J., Phillips, S., & Leathwick, J. (2015). Elith J. dismo: Species distribution modeling. 2014. R package version, 1-1.