Dear List,
I have very little experience with lists and am having some very basic
problems. I don't know how to add columns to the lower levels of a list, or
how to take something from the upper level and add it as a column to the lower
level. I am analyzing animal movement data in the package Adehabitat. I have
a list of animal movements called "cut.ltr" (class ltraj) that have been
divided into a series of "burst" - i.e. movements with no gaps in time over a
given threashold. I would like to
1. Add the speed to each item in the list, and also the burst. I can
calculate speed as:
sp<-lapply(cut.ltr,function(l){l$dist/l$dt})
This creates a list of the correct size. But I don't know how to add this to
my original list. I.e. add a column to the lower levels of the list called
"speed".
2. Add the burst to each lower level of the list. It is in the upper level,
but I don't know how to access it.
I have tried attribute(), attr(), cut.ltr$"burst", and several other creative
guesses.
The first five items in the upper level are below - cut.ltr[1:5], along with
head(cut.ltr[[1]]). I would like my final result to have two more columns in
cut.ltr[[1]]. One with speed, and the second with burst.
Thanks in advance for your help.
Tim
> cut.ltr[1:5]
*********** List of class ltraj ***********
Type of the traject: Type II (time recorded)
Irregular traject. Variable time lag between two locs
Characteristics of the bursts:
id burst nb.reloc NAs date.begin date.end
1 Abigail Abigail.1 47 0 2003-05-31 13:29:59 2003-06-01 00:59:56
2 Abigail Abigail.2 288 0 2003-06-18 17:28:11 2003-06-21 17:14:59
3 Abigail Abigail.3 10 0 2003-08-03 23:33:00 2003-08-04 01:43:58
4 Abigail Abigail.4 43 0 2003-08-04 08:15:25 2003-08-04 18:59:58
5 Abigail Abigail.5 78 0 2003-08-05 00:44:19 2003-08-05 20:15:00
> head(cut.ltr[[1]])
x y date dx dy dist dt
R2n abs.angle rel.angle
1 809189.8 2189722 2003-05-31 13:29:59 81.87136 315.3389 325.7937 901
0.0 1.316775 NA
2 809271.6 2190037 2003-05-31 13:45:00 13.00097 258.7351 259.0616 901
106141.5 1.520590 0.20381526
3 809284.6 2190296 2003-05-31 14:00:01 250.52656 669.2065 714.5634 898
338561.8 1.212584 -0.30800666
4 809535.2 2190965 2003-05-31 14:14:59 -171.14372 791.1522 809.4516 902
1665046.9 1.783836 0.57125215
5 809364.0 2191756 2003-05-31 14:30:01 302.26979 707.0157 768.9202 900
4169281.4 1.166785 -0.61705039
6 809666.3 2192463 2003-05-31 14:45:01 284.40962 725.2169 778.9919 900
7742615.6 1.197057 0.03027109
>
Tim Clark
Department of Zoology
University of Hawaii
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