Creates a model.frame for distance detection function fitting. It includes some pre-specified and computed variables with those included in the model specified by user (formula)
Arguments
- xmat
dataframe for ddf
- scale.formula
user specified formula for scale of distance detection function
- meta.data
user-specified meta.data (see
ddf- shape.formula
user specified formula for shape parameter of distance detection function
Details
The following fields are always included: detected, observer, binned, and optionally distance (unless null), timesdetected (if present in data). If the distance data were binned, include distbegin and distend point fields. If the integration width varies also include int.begin and int.end and include an offset field for an iterative glm, if used. Beyond these fields only fields used in the model formula are included.