A Taste of Purrr: Loading Multiple files in R
When you have multiple files you need to load into R, each to their own objects, you can use purrr to avoid writing object_name <- read.table(filepath) over and over again.
Purrr is a very nifty library in R that provides tools to manipulate lists in R. For this example, we’ll use map() and assign().
Let’s go through the steps:
1) Make a vector of file names
These should be your filepaths
library(tidyverse)
filepaths <- c(
"file1.csv",
"file2.csv",
"file3.csv"
)
# We're adding the names of the files as the names of each of the filepaths
filepaths <- filepaths %>% set_names(nm = basename(.) %>% tools::file_path_sans_ext())2) Read in the files to create a list of data frames
This will read in the data frame in the file path and name it the name from above
files <- purrr::map(filepaths, read_csv)Now we have a list of processed dataframes!
3) Save each object in the list to it’s own variable name
If you want to work with these objects separately in R, you may want them each saved as a separate data frame pmap is purrr’s function for mapping several variable to a function. .l is the list of parameters which are named .x, .y, etc. .f is the function which will be applied to the parameters (see RStudio’s purrr cheatsheet for more information for more information.)
It’s very important we set the environment to .GlobalEnv, because otherwise the objects won’t show up in our environmnet!
purrr::pmap(.l = list(.x = names(files), .y = files), .f = ~assign(.x, .y, envir = .GlobalEnv))