truncation argument to `ds` as string

[erex]

If truncation value is specified as a number within quotes, it is treated as a percentage, regardless of whether a percent sign is included.

Minimum reproducible example

library(Distance)
data(wren_lt)
max(wren_lt$distance) # distances range up to 100m
lotsa.trunc <- ds(wren_lt, key="hn", truncation="85") # erroneously attempt to truncate at 85m
> summary(lotsa.trunc)

Summary for distance analysis 
Number of observations :  25 
Distance range         :  0  -  15 

Model : Half-normal key function 
AIC   : 137.4026 

Detection function parameters
Scale coefficient(s):  
            estimate       se
(Intercept) 8.304527 38292.71

                      Estimate        SE        CV
Average p            0.9999977 0.1757829 0.1757833
N in covered region 25.0000574 4.3945984 0.1757835

[LHMarshall]

@erex @lenthomas The help for truncation states "either truncation distance (numeric, e.g. 5) or percentage (as a string, e.g. "15%")" from my interpretation of the help I would expect "10" to truncate 10% of the data as it is a string not a numeric.

I can modify the help to "either truncation distance (numeric, e.g. 5) or percentage (as a string, e.g. "15%" or "15" with the former recommended for clarity)" or would you like the functionality changing so that there has to be a % sign? This option will take a bit of work it was coded with the intention that string values are treated as % truncation.

If a truncation of "10" is provided I could add a warning that it is being treated as a % and not an absolute truncation value.

[erex]

Thanks for looking into this Laura. I would like the documentation to reflect what would happen if the argument value is provided as a string. I'm not quite sure of the value of issuing a warning (because if being used in a rmarkdown/quarto context the warning might be suppressed). Perhaps a better place to show what was done is in the summary() function to the ddf object element of a ds.model object:

ds.hn1<-ds(chital1, truncation = "5%", key = "hn", formula = ~Region.Label)
summary(ds.hn1$ddf)

produces

Summary for ds object
Number of observations :  211 
Distance range         :  0  -  0.05739503 
AIC                    :  -1292.381 
Optimisation           :  mrds (nlminb) 

Detection function:
 Half-normal key function 

Detection function parameters 
Scale coefficient(s): 
                       estimate         se
(Intercept)          -3.7763382 0.06573921
Region.LabelMM Hills  0.2162854 0.14774747

In the row labelled Distance range the truncation argument can be repeated to indicate whether this was a value or a percentage.

[LHMarshall]

I'll look into whether Eric's suggestion is possible