zfit {zfit}

zfit: Fit Models in a Pipe

Description

Improve the usage of model fitting functions within a piped work flow.

Details

zfit makes it easier to use a piped workflow with functions that don’t have the “correct” order of parameters (the first parameter of the function does not match the object passing through the pipe).

The issue is especially prevalent with model fitting functions, such as when passing and processing a data.frame (or tibble) before passing them to lm() or similar functions. The pipe passes the data object into the first parameter of the function, but the conventional estimation functions expect a formula to be the first parameter.

This package addresses the issue with three functions that make it trivial to construct a pipe-friendly version of any function:

• zfunction() reorders the arguments of a function. Just pass the name of a function, and the name of the parameter that should receive the piped argument, and it returns a version of the function with that parameter coming first.

• zfold() creates a fold (a wrapper) around a function with the reordered arguments. This is sometimes needed instead of a simple reordering, for example for achieving correct S3 dispatch, and for functions that report its name or other information in output.

• zfitter() takes any estimation function with the standard format of a formula and data parameter, and returns a version suitable for us in pipes (with the data parameter coming first). Internally, it simply calls the zfold() function to create a fold around the fitter function.

The package also includes ready made wrappers around the most commonly used estimation functions. zlm()and zglm() correspond to lm() and glm(), and zlogit(), zprobit(), and zpoisson(), use glm() to perform logistic or poisson regression within a pipe.

Finally, the package includes the zprint() function, which is intended to simplify the printing of derived results, such as summary(), within the pipe, without affecting the modeling result itself.

See Also

• zlm is the wrapper lm, probably the most common fitting function. The help file for this function includes several usage examples.

• zglm is a wrapper for glm, to fit generalized linear models.

• zprint is helpful for printing a summary of a model, but assigning the evaluated model to a variable