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:
library(adehabitatLT)
data(puechcirc)
pp <- na.omit(puechcirc)
pp2 <- cutltraj(pp, "dt > 1500")
Hope this helps,
Mathieu.
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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