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Measuring length of trajectories

4 messages · Jeri Wisman, Chris English, marta azores +1 more

Original
Jeri Wisman
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Hi all -

I am trying to measure the length of time of trajectories taken of seabird
movements to be able to relate time of flight to distance of flight. Any
suggestions of a function or package on how to measure the time? Thanks,

*Jeri Wisman* | Masters Candidate
Old Dominion University
Department of Biological Sciences
Mills Godwin Building, Room 312
Norfolk VA 23529 USA
Chris English
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Jeri,

Is your data some kind of attached to bird(s) gps data?

Chris
On Thu, May 24, 2018 at 9:12 AM, Jeri Wisman <jwism002 at odu.edu> wrote:

            

      
      
      
    

        

      
      
    

        

  
  


  


      

    

    

      
      

        


  

        

      marta azores
    

    

      
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Hi Jeri,

there are a lot of packages to measure the tag trajectories length. You can
start reading about library(move) and library(gdistance)


2018-05-24 13:12 GMT+00:00 Jeri Wisman <jwism002 at odu.edu>:

            

      
      
      
    

        

      
      
    

        

  
  


  


      

    

    

      
      

        


  

        

      Michael Sumner
    

    

      
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On Thu, 24 May 2018 at 23:32 Jeri Wisman <jwism002 at odu.edu> wrote:

        

            

      
      
      
    

        
There are very many, including adehabitatLT package and the trackDistance
function in the trip package (I know how that one works so it's easy for me
to help with, but it's not as sophisticated as adehabitat family so
pros/cons).

Both packages requires you to get your data into the right format. There's
more general capability in sp::spDists which has arguments longlat (set to
TRUE for great circle distances from longlat) and segments, which gives
sequential paired distances. Both adehabitatLT and trip will handle the
grouping of locations into separate paths (ordered by time).

I'd say it's worth trying some of the purpose-built packages, because then
some of the metrics can be extracted very easily (once you know your way
around). Explore the "Moving objects, trajectories" section of this Task
View

https://gist.github.com/mdsumner/0a3cb0e58bf9d37b782943ac269e1eff

and this list of recentish additions, pending update to the Task View,
which gives a taste of how much activity there is in this space(!).

https://gist.github.com/mdsumner/0a3cb0e58bf9d37b782943ac269e1eff

Cheers, Mike.