libbib (version 1.6.4)

fread_plus_date: Read a file and set a special libbib date attribute

Description

Takes a file name, reads it with data.table::fread, and sets an attribute called lb.date with a date extracted from the file name.

Usage

fread_plus_date(fname, allow.fallback.date = TRUE, ...)

Value

A data.table with an attribute called lb.date set

Arguments

fname

The file name to read

allow.fallback.date

A logical indicating whether, if no matching file name with a date is found, to use today's date as the date attribute. Default is TRUE.

...

Arbitrary arguments to use with fread

Details

The file name can be one with a valid ISO 8601 date (yyyy-mm-dd) already in it, or it can be a file name with the date elided.

For example, if there is a file you'd like to read on your disk called "iris-2021-05-08.csv", you can call this function with either "iris.csv" or "iris-2021-05-08.csv" as the file name.

When you call this function with a file name without an ISO 8601 date (e.g. "iris.csv.gz"), the file name extension ".csv.gz" is removed and the function looks for a file name beginning with "iris", a date, and the file extension. The file extension is considered to be anything after the first period in the base name. For example, if the file name given is "./my.data/iris.csv.gz", the extension is ".csv.gz". This means no period can be present in the base file name (after any directories) with the exception of the file extension.

If you call this function with "iris.csv" and there is no file name with an ISO 8601 date appended to that file name on your disk, and allow.fallback.date is TRUE, then the lb.date attribute is set to the current date.

Examples

if (FALSE) {
  # there's a file called "iris-2021-05-08.csv" on disk
  dat <- fread_plus_date("iris.csv")
  attribute(dat)$lb.date
  # [1] "2021-05-08

  # can also read the full file name
  dat <- fread_plus_date("iris-2021-05-08.csv")
  attribute(dat)$lb.date
  # [1] "2021-05-08
}