Breaking changes from `dht2` `object` field requirement

[dill]

dht2 now requires the object field in flatfile formatted data. This breaks some examples etc and we need to ensure that the data shipped with Distance conforms to this new format, that the examples site data also is formatted correctly and check our workshop teaching examples.

[lenthomas]

I'll fix the CTDS workshop materials.

[lenthomas]

@Erex, @dill is going to fix the distanceexamples that use dht2 but I wonder if you use it on your workshop at all - in that case, your code will need updated to have an object field in the flatfile.

[dill]

For reference, this code searches through Distance data and prints which sets lack an object field:

# check that all data included in Distance has an object field

library(Distance)

datasets <- data(package="Distance")

datasets <- datasets$results[,3]

datasets <- datasets[!grepl("_units", datasets)]

for(dd in datasets){
  data(list=dd)
  if(is.null(get(dd)$object)) cat(dd, "\n")
}

[dill]

The duiker analysis at https://examples.distancesampling.org/Distance-cameratraps/camera-distill.html seems to be the only example which this breaks. Currently re-running the analysis in isbjørn.

[dill]

I've uploaded the corrected version of the camera trap analysis here https://examples.distancesampling.org/Distance-cameratraps/camera-distill.html and it should update momentarily.

[lenthomas]

Looks good to me. Perhaps we could point to that in the release posting as an example of how one might go about getting an object ID into a flatfile - it's just 2 lines of code!