How to use R purrr to combine hundreds of Excel files/sheets

Question

I've got hundreds of Excel files with varying quantities of sheets within said files. I want to combine all these Excel files and sheets into one data frame. Lucky for me, all the sheets are in the same format (they're a template filled out by customers and uploaded to a central repository).

Let's simulate these Excel files and sheets with the code below:

library(tidyverse)
library(openxlsx)
library(readxl)
write.xlsx(list(iris, iris * 2, iris * 3), "three_sheets.xlsx")
write.xlsx(list(iris, iris / 2), "two_sheets.xlsx")

How would I use R purrr to combine these files and sheets into one data frame? And can I mutate a column to identify which file/sheet each row comes from? If purrr isn't the best choice for this type of problem feel free to point out other solutions.

Answer 1

purrr seems to be a good choice for such operation. You can do :

library(readxl)
library(purrr)

#Get full path of all excel files in the folder
all_files <- list.files('path/of/folder',pattern = '\\.xlsx$', full.names = TRUE)
For each file
result <- map_df(all_files, function(x) {
             #Get all the sheet names
             all_sheets <- excel_sheets(x)  
             #read the excel file with one sheet at a time
             map_df(all_sheets, ~read_excel(x, sheet = .x) %>% 
                       #add columns for filename and sheetname
                       dplyr::mutate(filename = basename(x), sheetname = .x))
})