Suggestion on specifying truncation when data are binned

[lenthomas]

A feature request:

In Distance for Windows, one specifies binning and can then left or right truncate at any cutpoint value. A facility like this would be convenient in Distance (and mrds) - so one would write code to investigate different truncation widths, like:

library(Distance)
data("wren_snapshot")
bin.cutpoints.100m <- bin.cutpoints <- c(0, 10, 20, 30, 40, 60, 80, 100, 120)
conversion.factor <- convert_units("meter", NULL, "hectare")
wrensnap.hn.t100 <- ds(data=wren_snapshot, key="hn", adjustment=NULL, 
                       transect="point", cutpoints=bin.cutpoints.100m,
                       convert.units=conversion.factor, truncation=100)
wrensnap.hn.t100 <- ds(data=wren_snapshot, key="hn", adjustment=NULL, 
                       transect="point", cutpoints=bin.cutpoints.100m,
                       convert.units=conversion.factor, truncation=80)
wrensnap.hn.t100 <- ds(data=wren_snapshot, key="hn", adjustment=NULL, 
                       transect="point", cutpoints=bin.cutpoints.100m,
                       convert.units=conversion.factor, truncation=60)

At present, this throws the error

Error in process.data(data, meta.data, check = FALSE) : 
  width must exceed largest interval end point


All models failed to fit!

Error in ds(data = wren_snapshot, key = "hn", adjustment = NULL, transect = "point",  : 
  No models could be fitted.

A similar facility would also be useful for left truncation.