4pike.R

library(tidyverse)
library(readxl)
library(writexl)

# which file to mess with
xlfile <- "~/tmp/bookofthedead.xlsx"

sheets <- excel_sheets(xlfile)
xlsheets <- map(sheets,~{
  read_xlsx(xlfile,sheet=.x)
}) %>% set_names(sheets)


# which sheet to mess with
which_sheet <- "first sheet"

# add the new column
xlsheets[[which_sheet]] <- xlsheets[[which_sheet]] %>%
  mutate(newcolumn = paste0("a new value plus ",seq(nrow(.))))

# write the new file
write_xlsx(xlsheets,"~/tmp/bookofthedead2.xlsx",format_headers = FALSE)