[FORGED] Re: help with r package "trip"

Hi Alice,
Have you tried creating a vector of the start position (xpos[1],ypos[1]):

xstart<-rep(xpos[1],n)
ystart<-rep(ypos[1],n)
# where "n" is the number of subsequent positions in the trip
max(trackDistance(xstart,ystart,xpos[2:n],ypos[2:n],...))

may then give you the value of the longest distance from the start. I
don't have the trip package or I could see if you really need to
replicate the start positions.

Jim:  This seems to me to be somewhat off the point.  The OP was faced 
with the problem of not being able to access the function homedist(). 
This function seems *not* to be exported from the trip package, and yet 
it is a *documented* function which I would assume to imply that users 
should be able to invoke it directly.

It is possible that in the past the OP was dealing with a version of the 
trip package that was created before namespaces came into the picture, 
whence "exporting" was not relevant.  I would suggest that the OP 
contact the package maintainer (maintainer("trip") will give you the 
email address) and enquire as to what is going on.

In the interim, a workaround *might* be to invoke homedist() as

     trip:::homedist(<whatever>)

Note the *triple* colon in the foregoing.  I am not at all familiar with 
the trip package so my advice should probably be taken with several 
grains of salt.

cheers,

Rolf Turner

Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276

> On Wed, Jun 15, 2016 at 1:43 PM, Alice Domalik <adomalik at sfu.ca> wrote:
>> Hi List,
>>
>> I'm relatively new to R, so apologies if my question is rather elementary.
>> I'm working with some bird tracking data and I would like to calculate the maximum distance traveled from the colony.
>> For the maximum distance traveled, I was going to use the function homedist(). However, when I try to use this function I get the following error:
>> Error: could not find function "homedist"
>> Anyone know why I would get this error? I have been using other functions in "trip" without an issue. Is there an alternative way I can calculate this?
>>
>> Thanks in advance for any help!