Subset traps Object
Retain selected rows of a traps object.
## S3 method for class 'traps' subset(x, subset = NULL, occasions = NULL, ...) ## S3 method for class 'traps' split(x, f, drop = FALSE, prefix = "S", byoccasion = FALSE, ...)
x |
|
subset |
vector to subscript the rows of |
occasions |
vector to subscript columns in |
... |
arguments passed to other functions or to optional subset function (subset.traps) |
f |
factor or object that may be coerced to a factor |
drop |
logical indicating if levels that do not occur should be dropped (if f is a factor) |
prefix |
a character prefix to be used for component names when values of f are numeric |
byoccasion |
logical ; if TRUE then f is used to split occasions |
The subscripts in subset may be of type integer, character or
logical as described in Extract. By default, all rows are retained.
In the case of ‘polygon’ and ‘transect’ detectors, subsetting is done at
the level of whole polygons or transects. subset should therefore
have the same length as levels(polyID(x)) or
levels(transectID(x)).
split generates a list in which each component is a traps
object. Each component corresponds to a level of f. The argument
x of split cannot be a list (i.e. x must be a
single-session traps object).
If the levels of f are numeric, from version 2.10.3 a leading zero is inserted in the names of the output list to maintain the sort order.
An object of class traps with only the requested subset of rows.
Subsetting is applied to usage and covariates attributes
if these are present.
Splitting with byoccasion = TRUE produces a list of traps
objects, each with usage codes for a subset of occasions. Traps not used
on any occasion within a session are automatically dropped from that
session.
## odd-numbered traps only, using modulo operator temptrap <- make.grid(nx = 7, ny = 7) t2 <- subset(temptrap, as.logical(1:nrow(temptrap) %% 2)) plot(t2) ## this works also for even number of rows, but must change 'outer' call temptrap <- make.grid(nx = 8, ny = 8) t3 <- subset(temptrap, !as.logical(outer(1:8,1:8,'+')%%2)) plot(t3)
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