Reads a text file in which the first column is a character string (see Note)
identifying a detector and the next two columns are its x- and
y-coordinates, separated by white space. The coordinates optionally may
be followed by a string of codes `0' or `1' indicating whether the
detector was operated on each occasion. Trap-specific covariates may be
added at the end of the line preceded by `/'. This format is compatible
with the Density software (Efford 2012), except that all detectors are
assumed to be of the same type (usage codes greater than 1 are treated
as 1), and more than one covariate may be specified.
If file is missing then x-y coordinates will be taken instead
from data, which should include columns `x' and `y'. Row names of
data are read as detector identifiers. This option does not allow
for covariates or usage, but they maybe added later.
detector specifies the behaviour of the detector following Efford
et al. (2009). `single' refers to a trap that is able to catch at most
one animal at a time; `multi' refers to a trap that may catch more than
one animal at a time. For both `single' and `multi' detectors a trapped
animals can appear at only one detector per occasion. Detectors of type
`proximity', such as camera traps and hair snags for DNA sampling, allow
animals to be recorded at several detectors on one occasion. See
detector for further detector types.
For polygon and transect detector types, each line corresponds to a
vertex and starts with a code to identify the polygon or transect (hence
the same code appears on 2 or more lines). For input from a dataframe
the code column should be named `polyID'. Also, usage and covariates
are for the polygon or transect as a whole and not for each
vertex. Usage and covariates are appended to the end of the line, just
as for point detectors (traps etc.). The usage and covariates for each
polygon or transect are taken from its first vertex. Although the
end-of-line strings of other vertices are not used, they cannot be blank
and should use the same spacing as the first vertex.