Determine file format — excel

Determine if files are xls or xlsx (or from the xlsx family).

excel_format(guess = TRUE) is used by read_excel() to determine format. It draws on logic from two lower level functions:

format_from_ext() attempts to determine format from the file extension.
format_from_signature() consults the file signature or "magic number".

File extensions associated with xlsx vs. xls:

xlsx: .xlsx, .xlsm, .xltx, .xltm
xls: .xls

File signatures (in hexadecimal) for xlsx vs xls:

xlsx: First 4 bytes are 50 4B 03 04
xls: First 8 bytes are D0 CF 11 E0 A1 B1 1A E1

Usage

excel_format(path, guess = TRUE)

format_from_ext(path)

format_from_signature(path)

Arguments

path: Path to the xls/xlsx file.
guess: Logical. If the file extension is absent or not recognized, this controls whether we attempt to guess format based on the file signature or "magic number".

Value

Character vector with values "xlsx", "xls", or NA.

Examples

files <- c(
  "a.xlsx",
  "b.xls",
  "c.png",
  file.path(R.home("doc"), "html", "logo.jpg"),
  readxl_example("clippy.xlsx"),
  readxl_example("deaths.xls")
)
excel_format(files)
#> [1] "xlsx" "xls"  NA     NA     "xlsx" "xls"