Hi there, I have seabird tracking data and I have used both the packages 'trip' and 'move' to calculate the max distance travelled (using the function 'homedist' in 'trip', and 'distanceSummary' in 'move'). I would also like to describe the bearing of each animal when it is at its maximum displacement from the colony. I am wondering if anyone knows any packages that can calculate this. Alternatively, if someone knows how I can extract the coordinates of the location of maximum displacement. thanks so much!
average bearing of animal movement data
5 messages · Alice Domalik, Barry Rowlingson, Michael Sumner +2 more
You can convert a "trip" object to a SpatialPointsDataFrame with
as("SpatialPointsDataFrame",my_trip). Then you can use functions like
"spDistsN1" from sp to compute the distance from "home" to each point,
find the maximum, and then use "bearing" from the "geosphere" package
to get the bearing for that row.
A complication I see is that this will only return the maximum
distance to a vertex point on the trip. For a trip in two flat
dimensions the maximum distance will always be a vertex point on the
trip but I think on a sphere its possible for great circles between
two points to have a location on the circle that is further from a
given point than either of the end points. But I can't get my head
quite round the 3d triangular geometry this early in the morning. For
small steps in a trip where you can approximate the geometry as flat
this is not a problem.
In contrast, the minimum distance from a trip to a "home" point is
rarely a vertex point on the trip because its possible for the trip
path to go very close to the home point in question. e.g a trip from
(10,0) to (-10,0) goes right through (0,0) but its points are both 10
units away.
Barry
On Wed, Aug 2, 2017 at 7:25 PM, Alice Domalik <adomalik at sfu.ca> wrote:
Hi there,
I have seabird tracking data and I have used both the packages 'trip' and 'move' to calculate the max distance travelled (using the function 'homedist' in 'trip', and 'distanceSummary' in 'move').
I would also like to describe the bearing of each animal when it is at its maximum displacement from the colony. I am wondering if anyone knows any packages that can calculate this. Alternatively, if someone knows how I can extract the coordinates of the location of maximum displacement.
thanks so much!
[[alternative HTML version deleted]]
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Also, trip is really outdated and dopey and homedist is likely not working properly, very happy to help find he answers here there are many options. Cheers, Mike at tripIsMyFault.org On Thu, 3 Aug 2017, 17:27 Barry Rowlingson, <b.rowlingson at lancaster.ac.uk> wrote:
You can convert a "trip" object to a SpatialPointsDataFrame with
as("SpatialPointsDataFrame",my_trip). Then you can use functions like
"spDistsN1" from sp to compute the distance from "home" to each point,
find the maximum, and then use "bearing" from the "geosphere" package
to get the bearing for that row.
A complication I see is that this will only return the maximum
distance to a vertex point on the trip. For a trip in two flat
dimensions the maximum distance will always be a vertex point on the
trip but I think on a sphere its possible for great circles between
two points to have a location on the circle that is further from a
given point than either of the end points. But I can't get my head
quite round the 3d triangular geometry this early in the morning. For
small steps in a trip where you can approximate the geometry as flat
this is not a problem.
In contrast, the minimum distance from a trip to a "home" point is
rarely a vertex point on the trip because its possible for the trip
path to go very close to the home point in question. e.g a trip from
(10,0) to (-10,0) goes right through (0,0) but its points are both 10
units away.
Barry
On Wed, Aug 2, 2017 at 7:25 PM, Alice Domalik <adomalik at sfu.ca> wrote:
Hi there, I have seabird tracking data and I have used both the packages 'trip'
and 'move' to calculate the max distance travelled (using the function 'homedist' in 'trip', and 'distanceSummary' in 'move').
I would also like to describe the bearing of each animal when it is at
its maximum displacement from the colony. I am wondering if anyone knows any packages that can calculate this. Alternatively, if someone knows how I can extract the coordinates of the location of maximum displacement.
thanks so much!
[[alternative HTML version deleted]]
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Dr. Michael Sumner Software and Database Engineer Australian Antarctic Division 203 Channel Highway Kingston Tasmania 7050 Australia [[alternative HTML version deleted]]
Dear Alice, Since Move inherits a SpatialPointsDataFrame the finding the location furthers away can be done as follows (under the assumption the data are longlat and the caveat pointed out by Barry): > require(move) > data(leroy) > which.max(spDistsN1(leroy, c(-40,40), longlat=T)) [1] 600 Best Bart
On 03.08.2017 10:00, Michael Sumner wrote:
Also, trip is really outdated and dopey and homedist is likely not working properly, very happy to help find he answers here there are many options. Cheers, Mike at tripIsMyFault.org On Thu, 3 Aug 2017, 17:27 Barry Rowlingson, <b.rowlingson at lancaster.ac.uk> wrote:
You can convert a "trip" object to a SpatialPointsDataFrame with
as("SpatialPointsDataFrame",my_trip). Then you can use functions like
"spDistsN1" from sp to compute the distance from "home" to each point,
find the maximum, and then use "bearing" from the "geosphere" package
to get the bearing for that row.
A complication I see is that this will only return the maximum
distance to a vertex point on the trip. For a trip in two flat
dimensions the maximum distance will always be a vertex point on the
trip but I think on a sphere its possible for great circles between
two points to have a location on the circle that is further from a
given point than either of the end points. But I can't get my head
quite round the 3d triangular geometry this early in the morning. For
small steps in a trip where you can approximate the geometry as flat
this is not a problem.
In contrast, the minimum distance from a trip to a "home" point is
rarely a vertex point on the trip because its possible for the trip
path to go very close to the home point in question. e.g a trip from
(10,0) to (-10,0) goes right through (0,0) but its points are both 10
units away.
Barry
On Wed, Aug 2, 2017 at 7:25 PM, Alice Domalik <adomalik at sfu.ca> wrote:
Hi there, I have seabird tracking data and I have used both the packages 'trip'
and 'move' to calculate the max distance travelled (using the function 'homedist' in 'trip', and 'distanceSummary' in 'move').
I would also like to describe the bearing of each animal when it is at
its maximum displacement from the colony. I am wondering if anyone knows any packages that can calculate this. Alternatively, if someone knows how I can extract the coordinates of the location of maximum displacement.
thanks so much!
[[alternative HTML version deleted]]
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An alternative solution would be to use adehabitatLT to prepare your trajectories. If you set them to start at the colony (i.e. the first location is at the colony), then you have nothing to do: - ltraj objects provide the squared net displacement (R2n), which you can use to find the furthest point from the colony (max R2n); - ltraj objects provide absolute and relative bearings for each point, and you already have the coordinates associated to it. Hope this helps, Mathieu.
On 08/02/2017 02:25 PM, Alice Domalik wrote:
Hi there, I have seabird tracking data and I have used both the packages 'trip' and 'move' to calculate the max distance travelled (using the function 'homedist' in 'trip', and 'distanceSummary' in 'move'). I would also like to describe the bearing of each animal when it is at its maximum displacement from the colony. I am wondering if anyone knows any packages that can calculate this. Alternatively, if someone knows how I can extract the coordinates of the location of maximum displacement. thanks so much! [[alternative HTML version deleted]]
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-- Mathieu Basille basille at ufl.edu | http://ase-research.org/basille +1 954-577-6314 | University of Florida FLREC ? Le tout est de tout dire, et je manque de mots Et je manque de temps, et je manque d'audace. ? ? Paul ?luard
Mathieu Basille basille at ufl.edu | http://ase-research.org/basille +1 954-577-6314 | University of Florida FLREC ? Le tout est de tout dire, et je manque de mots Et je manque de temps, et je manque d'audace. ? ? Paul ?luard