Description Usage Arguments Details Value Author(s) See Also Examples

Make a spatial region composed of discs with given centres and radii.

1 2 3 |

`centres` |
Point pattern giving the locations of centres for the discs. |

`radii` |
Vector of radii for each disc, or a single number giving a common
radius.
(Notice that the default assumes that the marks of |

`...` |
Optional arguments passed to |

`separate` |
Logical. If |

`mask` |
Logical. If |

`trim` |
Logical value indicating whether to restrict the result
to the original window of the |

`delta` |
Argument passed to |

`npoly` |
Argument passed to |

This command is typically applied to a marked point pattern
dataset `X`

in which the marks represent the sizes of objects.
The result is a spatial region representing the space occupied by
the objects.

If the marks of `X`

represent the diameters of circular objects,
then the result of `discs(X)`

is a spatial region constructed by taking discs, of the specified
diameters, centred at the points of `X`

, and forming the union
of these discs. If the marks of `X`

represent the areas of
objects, one could take `discs(X, sqrt(marks(X)/pi))`

to produce discs of equivalent area.

A fast algorithm is used to compute the result as a binary mask, when
`mask=TRUE`

. This option is recommended unless polygons are
really necessary.

If `mask=FALSE`

, the discs will be constructed as polygons
by the function `disc`

. To avoid computational problems,
by default, the discs will all be constructed using
the same physical tolerance value `delta`

passed to `disc`

. The default is such that the smallest
disc will be approximated by a 16-sided polygon.
(The argument `npoly`

should not normally be used, to avoid
computational problems arising with small radii.)

If `separate=FALSE`

, a window (object of class `"owin"`

).

If `separate=TRUE`

, a list of windows.

.

1 |

spatstat documentation built on May 30, 2017, 7:53 a.m.

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