加载一个功能包

Question

I would like to load an entire package apart from one function.

I see workarounds such as How to load only specific functions from a package but this does not fulfil my full needs.

The specific problem is using loading the select() function within the MASS and tidyverse packages but I would like a more general solution.

Thank you.

Answer 1

There are three nice ways to do that, rising in difficulty:

1. conflicted

It checks for name conflicts and will prevent you from using masked or masking functions by throwing an error if you do. But you can declare a session-wide preference, eg:

conflict_prefer("filter", "dplyr")
#> [conflicted] Will prefer dplyr::filter over any other package

conflicted on Github

2. import

It allows you to explicitly import specific functions from packages (and give them a custom name, if you like)

import::from(ggplot2, g = ggplot, aes, geom_point)
g(iris, aes(Petal.Width, Petal.Length)) + geom_point()

import on Github

3. modules

It gives you a Python-esque way of importing both modules (written as R source files) and libraries and a more cohesive fashion. The nice (but advanced) thing is that modules, if they have subgroups, can be loaded partially, eg str = import('tools/strings') . This does not work for packages, however, as they are written as monoliths. modules has some advantages coding guideline wise, but will force you to write:

dplyr = import_package('dplyr')
cars %>% dplyr$filter(speed > 15)

modules on Github

Answer 2

If you do select <- MASS::select you should be fine.

If you really don't want it in your global workspace you could do, after attaching MASS (optionally), and dplyr :

attach(list(select=MASS::select),name = "front_select")

This way it will find this one before the others because the environment front_select will be met first in the search path.

That's not very orthodox though.

This is assuming you want this for interactive use, if not by all means use :: notation.

---

Actually what you're asking for is possible, though it's a lot of black wizardry, and I have a feeling I'll get downvoted for this, but this answers the question :

library(dplyr)
x <- as.list(as.environment("package:dplyr"))
detach("package:dplyr")
x$select <- NULL
attach(x,name = "package:dplyr")
mutate
# function (.data, ...) 
# {
#     UseMethod("mutate")
# }
# <bytecode: 0x00000000190069c0>
# <environment: namespace:dplyr>

select
# Error: object 'select' not found

from ?search :

Names starting "package:" are reserved for library and should not be used by end users.