[AniMov] cutltraj function error (adehabitatLT)

Mathieu Basille basille.web at ase-research.org
Mon Feb 16 20:39:50 CET 2015

As said in the help file:

criterion: a character string giving any syntactically correct R
           logical expression implying the descriptive parameters in ‘x’

Try to put your criterion within quotes, such as:

df <- cutltraj (depurelt, "dt > 3600", nextr = TRUE)

I tested it with the 'puechcirc' dataset:

pp <- na.omit(puechcirc)
pp2 <- cutltraj(pp, "dt > 1500")

Hope this helps,

Le 16/02/2015 07:32, Jose Manuel de los Reyes a écrit :
> Hi all,
> I'm working with GPS dataset from seabirds that include more than one trip
> for each burst, and currently I'm trying to split then automatically in
> sub-burst based on a criterion.
> To do that I'm trying to use the function cutltraj from AdehabitatLT R
> package. Previously I removed all positions matching an specific condition,
> so now, after applying the as.ltraj function, my dataframe has ltraj class
> and I can use the dt field values as criterion to make the split.
> This criterion is so simple: time between two position > 3600  (units in
> seconds). This time is enough to determine when the burst need to be splited.
> I applied it:
> df <- cutltraj (depurelt, dt>3600, nextr = TRUE)
> According to this, a logical vector (with TRUE when criterion does match)
> should work for splitting.  If I check with the common datframe class, dt
> field exists and it's correct, and the logical function dt>3600 run
> correctly and I get a TRUE-FALSE vector.
> However, when I run the function I got this error message:
> Error in dt > 3600 :
>    comparison (6) is possible only for atomic and list types
> Since ltraj class is in fact a list object, I don't understand why I get
> this error.
> If someone have any idea why is this happening, please let me know.
> Thank you in advance.
> jose
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Mathieu Basille

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University of Florida \\
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