Function to read lots of libraries

You want to start a new analysis script in R

The thing is, you’re gonna need lots of packages. Say you’re interested in examining some descriptive statistics, generating a Confirmatory Factor Analysis and doing an IRT on some questionnaire items. Reasonable packages for these operations could be:

library(dplyr)
library(lavaan)
library(magrittr)
library(mirt)
library(psych)
library(QuantPsyc)
library(qgraph)
library(semPlot)
library(tidyr)

Let me save you some trouble: you could have some issues with the code above. For me, I noticed the following:

1. Everytime I updated R, I had to download every package again. That was a very boring task to do.
2. When I shared my script with someone who didn’t have the same packages I was reading with the library function, that person now had to install the packages they didn’t had.
3. When restarting a R session, I had to click and drag on all those library lines to make sure I read them again in that session.

That happened with me constantly until I stumbled upon this code here. The if (!require("package"));install.packages("package") was very ingenious. I started using that, then I adapted the code with a library(package) extension; then I created a function to read all of them at once.

The code we saw above I now write as:

load_libraries <- function(){
  if (!require("dplyr"))
    install.packages("dplyr"); library(dplyr)
  if (!require("lavaan"))
    install.packages("lavaan"); library(lavaan)
  if(!require("magrittr"))
    install.packages("magrittr"); library(magrittr)
  if(!require("mirt"))
    install.packages("mirt"); library(mirt)
  if (!require("psych"))
    install.packages("psych"); library(psych)
  if (!require("QuantPsyc"))
    install.packages("QuantPsyc"); library(QuantPsyc)
  if (!require("qgraph"))
    install.packages("qgraph"); library(qgraph)
  if (!require("semPlot"))
    install.packages("semPlot"); library(semPlot)
  if (!require("tidyr"))
    install.packages("tidyr"); library(tidyr)
}

load_libraries()

For me, the main idea of this code is reproducibility. Even if someone doesn’t have those packages, they can read the function and get on with their lives.

I hope this helps someone someday as much as it helped me.