Description Usage Arguments Details Value References See Also

View source: R/stamp.distance.r

The function `stamp.distance`

can be used to compute various measures of distance
between polygon events and groups. In turn, distance measurements can be used to estimate the velocity
of polygon movement.

1 | ```
stamp.distance(stmp, dist.mode = "Centroid", group = FALSE)
``` |

`stmp` |
a |

`dist.mode` |
Character determining the emethod by which polygon distances are computed. If |

`group` |
logical indicating whether distances should be computed from the T1 polygon to each individual
stamp event ( |

`stamp.distance`

computes distance between polygon sets based on either centroid or
Hausdorff distance calculations. Centroid distance is simply the distance from the centroid
of all T1 polygons (combined) to each stamp event (`group = FALSE`

), or to the union of
all T2 polygons within a group (`group = TRUE`

), in the second case, all events within a group
are given an identical distance value.

The Hausdorff distance calculation uses the discrete version of the Hausdorff distance, as
programmed in the `rgeos`

function `gDistance`

. A value of `densifyFrac = 1`

is used
to increase the precision of this measurement – see `help(gDistance)`

. The returned distance
is then the Hausdorff distance of all T1 polygons (combined) to each stamp event (`group = FALSE`

),
or to the union of all T2 polygons within a group (`group = TRUE`

), in the second case, all events
within a group are given an identical distance value.

Appropriately named columns (e.g., `CENDIST`

or `HAUSDIST`

) in the stamp `SpatialPolygonsDataFrame`

object.

Hausdorff Distance: http://en.wikipedia.org/wiki/Hausdorff_distance

stamp stamp.direction stamp.shape gDistance

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