15 How to create a package

15.1 What is an R package?

An R package is a folder that contains required files and sub-folders. In RStudio, it is easy to create an R package.

15.2 Two handy tools

  • devtools
  • roxygen2

15.3 The procedure

  • Step 1: Create the “structure”, which is an empty folder containing required although empty sub-folders and files, in RStudio. file>new project…>package

  • Step 2: Write R files and save them in the R folder. An example:

#' find key information about a dataframe
#'
#' This function allows you to find key information about a dataframe
#' @param a_df a dataframe
#' @keywords key info; dataframe
#' @export
#' @author Lingyun (Larry) Zhang \email{lyzhang10@gmail.com}
#' @examples
#' temp_df <-
#'      data.frame(a = 1:10,
#'                 b = NA,
#'                 e = c(letters[1:8], NA, NA))
#' x <- find_df_key_info(temp_df)

#' @importFrom magrittr %>%

find_df_key_info <- function(a_df)
{re_df <-
  data.frame(vari_names = names(a_df)) %>%
  dplyr::mutate(type = purrr::map_chr(a_df, typeof),
                no_of_unique_rows = purrr::map_int(a_df, function(x) length(unique(x))),
                no_of_rows = dim(a_df)[1],
                no_of_NAs = purrr::map_int(a_df, function(x) sum(is.na(x))))
 return(re_df)
}
  • Step 3: Run the following R code
library(devtools)
library(roxygen2)
document()
  • Step 4: Work on DESCRIPTION file. An example:
Package: dfexplorer
Type: Package
Title: 'dfexplorer' for explore new dataframe
Version: 0.1.0
Author: Lingyun (Larry) Zhang
Maintainer: Lingyun (Larry) Zhang <lyzhang10@gmail.com>
Description: This package contains functions for explore "new" data in a dataframe
Imports:
    dplyr, 
    magrittr,
    purrr
License: GPL-3
Encoding: UTF-8
LazyData: true
RoxygenNote: 6.1.1

  • Step 5: Build the package by clicking on the Build button and …

  • Step 6: Version control—link to a repo in Github
    • initialize the project. Tools>Version Control>…
    • stage and commit
    • create a repo under your Github account
    • set up connection by clicking Git button; then clicking on the “two purple boxes and a white square” in the Git pane …. (Key parameters: new branch name master; remote name origin. Reference: section 17.5.3 on https://happygitwithr.com/existing-github-last.html)
    • commit and push