extract_date: Extract and parse dates within strings such as file names
In epicentre-msf/llutils: Linelist Utilities

Description Usage Arguments Value Examples

Extract and parse dates within strings such as filenames. Currently handles formats "yyyy?mm?dd" and "dd?mm?yyyy", where "?" represents an optional space or punctuation character.

Includes options for dealing with multiple dates within a string (return either the first or last), and handling dates that can be parsed in both ymd and dmy formats (return ymd, dmy, or whichever ends up being closer to the present day).

extract_date(
  x,
  remove_path = TRUE,
  year_min = 2000,
  year_max = as.integer(format(Sys.Date(), "%Y")),
  if_multiple = "use_last",
  if_conflict = "use_latest"
)

`x`	Vector of strings such as file names
`remove_path`	Logical indicating whether to strip file paths from `x` using `basename` (up to and including the last path separator) prior to searching for date values. Defaults to `TRUE`.
`year_min`	Minimum year value expected. Targeting an expected year range helps avoid false positive matches to number sequences that are not dates. Defaults to `2000`.
`year_max`	Maximum year value expected. Defaults to the current year based on `Sys.date`.
`if_multiple`	If multiple dates of a given type (ymd or dmy) found within a string, proceed with only the first ("use_first"), or only the last ("use_last"). Defaults to "use_last".
`if_conflict`	If a given string matches both ymd and dmy formats (e.g. "2020_06_10_2020"), return the ymd format ("use_ymd"), the dmy format ("use_dmy"), or whichever of the two is closer to the current date ("use_latest"). Defaults to "use_latest".

Vector of dates. Returns NA when no date found within a given string.

files <- c(
  "~/Documents/2020-05-01/myfile-2020-04-30-1230.csv",
  "2020_06_30_052051_Database_Complete_v1230.csv",
  "2020_06_10_2020_Database_Complete_v1230.csv",
  "~/Desktop/data__cleaned1.xlsx",
  "~/Desktop/data__cleaned__2020-07-01_16-25.xlsx",
  "22062020-covid19-cases.xlsm",
  "/Documents/2015/PhD.Data.20091205_1247.Final.xls",
  "/exports/Cleaning 2016-03-05/export-2015-03-05_1352.xls",
  "COVID19_28072020.xlsb"
)

extract_date(files)

# prefer date within first portion of file path, if matched
extract_date(files, remove_path = FALSE, if_multiple = "use_first")