subset.traps: Subset traps Object

subset.trapsR Documentation

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, ...)



traps object


vector to subscript the rows of x


vector to subscript columns in usage(x)


arguments passed to other functions or to optional subset function (subset.traps)


factor or object that may be coerced to a factor


logical indicating if levels that do not occur should be dropped (if f is a factor)


a character prefix to be used for component names when values of f are numeric


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.


split.traps does not work for mark–resight data.

See Also

traps, rbind.traps


## odd-numbered traps only, using modulo operator
temptrap <- make.grid(nx = 7, ny = 7)
t2 <- subset(temptrap, as.logical(1:nrow(temptrap) %% 2))

## 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))

secr documentation built on May 29, 2024, 5:44 a.m.