Several answers to your question are already available here:
http://lists.faunalia.it/pipermail/animov/2010-June/000601.html
http://lists.faunalia.it/pipermail/animov/2010-June/000602.html
Please avoid cross-posting,
Best,
Clément Calenge
On 06/03/2010 04:18 PM, Abdi, Abdulhakim wrote:
> Dear List,
>
> I'm trying to detect patterns in the movements of a nomadic gazelle species
> during the breeding season. Basically, I would like to create MCPs (minimum
> convex polygons representing home ranges) for each of the 32 gazelles every
> two weeks starting on September 4th 2007. I have satellite tracking points
> from September 2007 to January 2010. The point of this exercise is to see
> whether the animals converge at particular areas during the breeding season
> or whether the site selection is random.
>
> Before going into the date loop procedure I attempted to create MCPs for the
> animals without regard for the two-week interval:
>
> Here is what my data.frame looks like:
>
>
>> head(all.frame)
>>
> Name Status X Y Date
> 1 76792 capture 1356206 2196167 2007-09-04
> 2 76795 capture 1354434 2209845 2007-09-04
> 3 76797 capture 1354434 2209845 2007-09-04
>
> And here is the output of the command, as you can see I get an error
> statement:
>
>
>> all.xy = all.frame[,c("X","Y")]
>> all.id = all.frame$Name
>> all.mcp = mcp(all.xy, all.id, percent=95)
>>
> Error in mcp(all.xy, all.id, percent = 95) :
> At least 5 relocations are required to fit an home range
>
> Next, I ran MCPs for the "puechabon$loc" data.frame that comes with
> Adehabitat and it worked without producing any errors, so I compared my
> data.frame with puechabon$loc.
>
>
>> head(puechabon$loc)
>>
> Name Age Sex X Y Date
> 1 Brock 2 1 699889 3161559 930701
> 2 Brock 2 1 700046 3161541 930703
> 3 Brock 2 1 698840 3161033 930706
>
> Looking at the structure of both, my dataset has the date set to class 'Date'
> while in the Puechabon dataset it's set to 'Integer' and the dates are
> concatenated as "yymmdd":
>
>
>> str(all.frame)
>>
> 'data.frame': 5059 obs. of 5 variables:
> $ Name : Factor w/ 32 levels "76790","76792",..: 2 5 7 7 1 3 5 8 7 7 ...
> $ Status: Factor w/ 3 levels "argos","capture",..: 2 2 2 3 2 2 1 2 3 3 ...
> $ X : int 1356206 1354434 1354434 1349773 1362802 1362802 1357468
> 1362802 1345648 1345387 ...
> $ Y : int 2196167 2209845 2209845 2211725 2216920 2216920 2176051
> 2216920 2213362 2213572 ...
> $ Date :Class 'Date' num [1:5059] 13760 13760 13760 13761 13761 ...
>
>
>> str(puechabon$loc)
>>
> 'data.frame': 119 obs. of 6 variables:
> $ Name: Factor w/ 4 levels "Brock","Calou",..: 1 1 1 1 1 1 1 1 1 1 ...
> $ Age : int 2 2 2 2 2 2 2 2 2 2 ...
> $ Sex : int 1 1 1 1 1 1 1 1 1 1 ...
> $ X : int 699889 700046 698840 699809 698627 698719 698991 698626 698879
> 699756 ...
> $ Y : int 3161559 3161541 3161033 3161496 3160941 3160989 3161015
> 3160768 3160964 3161449 ...
> $ Date: int 930701 930703 930706 930707 930708 930709 930713 930714 930715
> 930720 ...
>
> I tried to convert my dates to the "yymmdd" format, without any luck as the
> new column came out exactly the same as the original one:
>
>
>> all.frame$Date2 = as.Date(all.frame$Date, format="%y/%m%/d")
>> head(all.frame)
>>
> Name Status X Y Date Date2
> 1 76792 capture 1356206 2196167 2007-09-04 2007-09-04
> 2 76795 capture 1354434 2209845 2007-09-04 2007-09-04
> 3 76797 capture 1354434 2209845 2007-09-04 2007-09-04
>
> So, I have three questions: is it only a date format issue or am I missing
> something else? If it is a date format issue, then, how would it be possible
> to convert my dates in "YYyy-mm-dd" into "yymmdd"? and finally what loop
> functions or steps could I take to create MCPs for the animals every two
> weeks.
>
> Any help is greatly appreciated.
>
> Regards,
>
> Hakim Abdi
>
> _________________________________
> Abdulhakim Abdi, M.Sc.
> Research Intern
>
> Conservation GIS/Remote Sensing Lab
> Smithsonian Conservation Biology Institute
> 1500 Remount Road
> Front Royal, VA
> phone: +1-540-635-6578
> fax: +1-540-635-6506
> email: [email protected]<mailto:[email protected]>
>
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>
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>
>
--
Clément CALENGE
Cellule d'appui à l'analyse de données
Office national de la chasse et de la faune sauvage
Saint Benoist - 78610 Auffargis
tel. (33) 01.30.46.54.14
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