The R equivalent of Python `from x import y as z`

Question

In python I can load a specific function or functionality with:

from x import y as z

How can I replicate this in R?

For instance, I want to load just the count function from plyr, instead of loading the entire package with library(plyr)

Answer 1

I'd probably just do count <- plyr::count, so I wouldn't have to bother with ensuring I get the arguments correct.

And you might want to wrap that definition in an if statement, in case plyr isn't installed:

if (requireNamespace("plyr"))
    count <- plyr::count
else
    stop("plyr is not installed.")

Also you might be interested in the import and/or modules packages, which provide python-like import/module mechanisms for R.

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Also heed the warning from the Adding new generics section of Writing R Extensions (original emphasis):

Earlier versions of this manual suggested assigning foo.default <- base::foo. This is not a good idea, as it captures the base function at the time of [package] installation and it might be changed as R is patched or updated.

So it would be okay to use the count <- plyr::count syntax if it's defined in a script you're sourceing, but you should explicitly define a new function and specify all the arguments if you do this in a package.