Elegant way to check for missing packages and inst

Question

I seem to be sharing a lot of code with coauthors these days. Many of them are novice/intermediate R users and don't realize that they have to install packages they don't already have.

Is there an elegant way to call installed.packages(), compare that to the ones I am loading and install if missing?

Answer 1

Although the answer of Shane is really good, for one of my project I needed to remove the ouput messages, warnings and install packages automagically. I have finally managed to get this script:

InstalledPackage <- function(package) 
{
    available <- suppressMessages(suppressWarnings(sapply(package, require, quietly = TRUE, character.only = TRUE, warn.conflicts = FALSE)))
    missing <- package[!available]
    if (length(missing) > 0) return(FALSE)
    return(TRUE)
}

CRANChoosen <- function()
{
    return(getOption("repos")["CRAN"] != "@CRAN@")
}

UsePackage <- function(package, defaultCRANmirror = "http://cran.at.r-project.org") 
{
    if(!InstalledPackage(package))
    {
        if(!CRANChoosen())
        {       
            chooseCRANmirror()
            if(!CRANChoosen())
            {
                options(repos = c(CRAN = defaultCRANmirror))
            }
        }

        suppressMessages(suppressWarnings(install.packages(package)))
        if(!InstalledPackage(package)) return(FALSE)
    }
    return(TRUE)
}

Use:

libraries <- c("ReadImages", "ggplot2")
for(library in libraries) 
{ 
    if(!UsePackage(library))
    {
        stop("Error!", library)
    }
}

Answer 2

The coming version of RStudio (1.2), already available as a preview, will include a feature to detect missing packages in library() and require() calls, and prompt the user to install them:

Detect missing R packages

Many R scripts open with calls to library() and require() to load the packages they need in order to execute. If you open an R script that references packages that you don’t have installed, RStudio will now offer to install all the needed packages in a single click. No more typing install.packages() repeatedly until the errors go away!
https://blog.rstudio.com/2018/11/19/rstudio-1-2-preview-the-little-things/

This seems to address the original concern of OP particularly well:

Many of them are novice/intermediate R users and don't realize that they have to install packages they don't already have.

Answer 3

  packages_installed <- function(pkg_list){
        pkgs <- unlist(pkg_list)
        req <- unlist(lapply(pkgs, require, character.only = TRUE))
        not_installed <- pkgs[req == FALSE]
        lapply(not_installed, install.packages, 
               repos = "http://cran.r-project.org")# add lib.loc if needed
        lapply(pkgs, library, character.only = TRUE)
}

Answer 4

# List of packages for session
.packages = c("ggplot2", "plyr", "rms")

# Install CRAN packages (if not already installed)
.inst <- .packages %in% installed.packages()
if(length(.packages[!.inst]) > 0) install.packages(.packages[!.inst])

# Load packages into session 
lapply(.packages, require, character.only=TRUE)

Answer 5

 48 lapply_install_and_load <- function (package1, ...)
 49 {
 50     #
 51     # convert arguments to vector
 52     #
 53     packages <- c(package1, ...)
 54     #
 55     # check if loaded and installed
 56     #
 57     loaded        <- packages %in% (.packages())
 58     names(loaded) <- packages
 59     #
 60     installed        <- packages %in% rownames(installed.packages())
 61     names(installed) <- packages
 62     #
 63     # start loop to determine if each package is installed
 64     #
 65     load_it <- function (p, loaded, installed)
 66     {
 67         if (loaded[p])
 68         {
 69             print(paste(p, "loaded"))
 70         }
 71         else
 72         {
 73             print(paste(p, "not loaded"))
 74             if (installed[p])
 75             {
 76                 print(paste(p, "installed"))
 77                 do.call("library", list(p))
 78             }
 79             else
 80             {
 81                 print(paste(p, "not installed"))
 82                 install.packages(p)
 83                 do.call("library", list(p))
 84             }
 85         }
 86     }
 87     #
 88     lapply(packages, load_it, loaded, installed)
 89 }

Answer 6

Use packrat so that the shared libraries are exactly the same and not changing other's environment.

In terms of elegance and best practice I think you're fundamentally going about it the wrong way. The package packrat was designed for these issues. It is developed by RStudio by Hadley Wickham. Instead of them having to install dependencies and possibly mess up someone's environment system, packrat uses its own directory and installs all the dependencies for your programs in there and doesn't touch someone's environment.

Packrat is a dependency management system for R.

R package dependencies can be frustrating. Have you ever had to use trial-and-error to figure out what R packages you need to install to make someone else’s code work–and then been left with those packages globally installed forever, because now you’re not sure whether you need them? Have you ever updated a package to get code in one of your projects to work, only to find that the updated package makes code in another project stop working?

We built packrat to solve these problems. Use packrat to make your R projects more:

• Isolated: Installing a new or updated package for one project won’t break your other projects, and vice versa. That’s because packrat gives each project its own private package library.
• Portable: Easily transport your projects from one computer to another, even across different platforms. Packrat makes it easy to install the packages your project depends on.
• Reproducible: Packrat records the exact package versions you depend on, and ensures those exact versions are the ones that get installed wherever you go.

https://rstudio.github.io/packrat/