在R中导入多个Excel文件时如何添加文件名？

Question

I am new to R and learning as I go. I'm trying to import a series of Excel files and then export them as one single file. The code below works fine for that. However, I cannot figure out how to add a filename to each row of the data that corresponds to the filename it came from. The filenames are in a pattern "YYYYMMDD-....." and I would like to crop that so only the YYYYMMDD is saved as the filename.

*# Import series of files from Excel
library(readxl)
file.list <- list.files(pattern='*.xls')
df.list <- lapply(file.list, read_excel)

# Combine all Excel files into one dataframe
library(dplyr)
df <- bind_rows(df.list, .id = "id")

# Export to Excel
library(writexl)
write_xlsx(df,"my file path goes here")

Any help you can provide would really help me from throwing my laptop across the room! Thanks!

Answer 1

should be fairly straight forward:

library(readxl)
library(purrr)
library(stringr)
file.list <- list.files(pattern='*.xls')
df <- map_dfr( file.list, ~ read_excel(.x) %>% mutate( File = str_match( .x, "\\d{8}" )[,1] ) )

Note I don't have a set of xls files to try this on.

Answer 2

Assuming that your vector of file names, file.list , looks something like this:

file.list <- c("20200101-foo1.xls", "20210101-foo2.xls")

The trick is to make df.list a named list. You can use stringr::str_replace to make the YYYYMMDD names. In this example, remove everything from the "-" onwards:

library(stringr)
file.list %>% str_replace("-.+", "")
[1] "20200101" "20210101"

So supply the names to the list like this:

names(df.list) <- file.list %>% 
  str_replace("-.+", "")

And now bind_rows with the .id argument will create a column with the names:

df <- bind_rows(df.list, .id = "filename")