spaMM (version 2.2.0)

good-practice: Clear and trustworthy formulas

Description

Base fitting functions in R will seek variables in the global environment (or more generally in the environment where a call to `~` was made, defining the model formula) if they are not in the data. This easily leads to errors (see example in the discussion of update.HLfit). Indeed Chambers (2008, p.221), after describing how the environment is defined, comments that “Where clear and trustworthy software is a priority, I would personally avoid such tricks. Ideally, all the variables in the model frame should come from an explicit, verifiable data source...”. Hence, the main fitting functions in spaMM depart from the sloppy practice. They strip the formula environment from any variable, and seek all variables from the formula in the data frame given by their data argument. One never needs to specify the data in the formula. The variables defining the prior.weights should also be in the data. Variables used in other arguments such as ranFix are looked up neither in the data nor in the formula environment, but in the calling environment as usual.

Arguments

References

Chambers J.M. (2008) Software for data analysis: Programming with R. Springer-Verlag New York