3.3 Structuring and constructing modules part 3: Reading and adding data

When constructing modules, sometimes you a built-in data frame, or any object outside from functions. Let’s explore how to effectively import / export and manage different types of data using {box}. It could be an atomic vector, a list, a matrix, a data frame, an n-dimensional array, and so on.

In this guide, especially for data frames later, I’ll be using the mpg dataset from {ggplot2} package, and saved it as mpg.rds to load it via readRDS() function within the module.

---

3.3.1 Creating a module for the data

The steps are trivial, (almost) every steps are similar to the process in R packages.

3.3.1.1 File “extension”

There’s a script under {./module} folder named not_func.r, where non-functions are contained.

Under {./module} folder, copy and paste this code:

box::use(
    tibble[as_tibble]
)

#' @export
pi = pi

#' @export
iris = as_tibble(datasets::iris)

#' @export
sales = readRDS(box::file('data/sales.rda'))

Note

No need to place #' @export as the code were being exported into namespace of the modules anyways. Only use #' @export if you preferred to specifically export some saved R codes into the namespace of the module. When you load external packages or modules with box::use(), only what’s inside the namespace of the package to be exported.

Save that script and then load the module:

box::use(
    module/not_func
)

If you have the initial file, you can import {./module/not_func.r} as {not_func} module within []. For example:

box::use(
    md_dt = ./module[not_func]
)

But remember, it will append another environment in the current environment, specifically under {./module} environment for {not_func}, and then create {md_dt} to load the entire {./module} afterwards.

3.3.1.2 Loading an object

If you did the following:

box::use(
    md_dt = ./module[not_func]
)

you can now access the data like this:

not_func$pi
not_func$iris
head(not_func$mpg, 5)

If it is the other way around:

box::use(
    md_dt = ./module/not_func
)

you are allowed to do this:

md_dt$pi
md_dt$iris
head(md_dt$mpg, 5)

Don’t forget that granular imports are allowed:

box::use(
    ./module/not_func[pi, iris, sales]
)

And access freely in R:

pi
iris
head(sales, 5)

Just don’t forget to maintain your current environment to avoid conflicts.

And that’s how it is done. I hope you followed the steps so that you can proceed to the next part.