Hello R Help Group:
I have been struggling to create
an object of class ltraj with the function as.ltraj (adehabitatLT) with my bird
data. Regarding my data structure, I
have GPS for 10 birds that transmit three times/day, over the course of a year
(with missing data). I have a L10.csv
file with the following headers: Craneid, Date, Time, Long, Lat, Habitat, ID
(for burst).
Step 1: Bring in my data with: �stringsasFactors=FALSE� to convert all
variables from Factor (except Lat/Long) to strings. Thanks to David Carlson
for that tip! Step 2: Transform my date, time vectors into POSIXct as follows:
datetime=as.POSIXct(strptime(paste(L10$Date, L10$Time, sep="
"),format="%m/%d/%Y %H:%M:%S", "America/Chicago")) Thanks to Petr Pikal for
that tip! Result: head(datetime)[1] "2011-07-10 17:00:38 CDT" "2011-07-11
00:01:06 CDT"[3] "2011-07-11 08:00:38 CDT" "2011-07-11 17:00:38 CDT"[5]
"2011-07-12 00:01:06 CDT" "2011-07-12 08:00:38 CDT" Good so far�. Step 3:
Coord=L10[c("Longitude", "Latitude")]> head(Coord) Longitude Latitude1
522598 33602852 522579 33601743 522618 33602744 522656 33601965
522397 33602076 522425 3360285 Good so far�.now comes the tricky part for
me. Step 4: Craneid=as.character(L10$Craneid) id=as.character(L10$ID)
Step 5: Test=as.ltraj(Coord, datetime, Craneid, burst=id,
type=TRUE)
Drum Roll Please�. Error in
as.ltraj(Coord, datetime, Craneid, burst = id, typeII = TRUE) :
non unique dates for a given burst
I include my data.frame for your
review.
head(l10b)
Longitude Latitude
datetime Craneid id
1 522598
3360285 2011-07-10 17:00:38
L1_10 L1_10
2 522579
3360174 2011-07-11 00:01:06
L1_10 L1_10
3 522618
3360274 2011-07-11 08:00:38
L1_10 L1_10
4 522656
3360196 2011-07-11 17:00:38
L1_10 L1_10
5 522397
3360207 2011-07-12 00:01:06
L1_10 L1_10
6 522425
3360285 2011-07-12 08:00:38
L1_10 L1_10
Longitude Latitude
datetime Craneid id
3803 558205
3346410 2011-04-15 17:00:38
L5_10 L5_10
3804 552813
3341251 2011-04-16 08:00:38
L5_10 L5_10
3805 552784
3341373 2011-04-28 08:00:38
L5_10 L5_10
3806 552833
3341262 2011-04-28 17:00:38
L5_10 L5_10
3807 573502
3407390 2011-06-21 17:00:38
L8_10 L8_10
3808 573271
3407499 2011-06-23 08:00:38
L8_10 L8_10
I have checked and re-checked for
duplicates and there are no duplicates. However,
when ask for duplicates in the datetime I get some �False� but a lot of �True�s�
So, I am thinking it has to do with the fact that R is not picking up the
individual birds which were monitored over the same time period.
How do I structure my data in R to recognize the 10 separate birds with their
associated coordinates and time
stamps?
I would ultimately like to run
Bias Bridge Movement on these data but I can�t get from square one! Help!
Thanks in advance for any and all
assistance you can provide�You all are so valuable.
TLP
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