Normalize dates to ISO 8601 format (YYYY-MM-DD)

The same day is written "31.12.2023", "12/31/2023", or "2023-12-31" depending on who typed it. normalize_date() parses these mixed formats and rewrites them to one ISO 8601 string (YYYY-MM-DD), so a date column matches on the day it names rather than on how it was formatted. It recognizes European (DD.MM.YYYY), American (MM/DD/YYYY), and ISO-style inputs.

Usage

normalize_date(x, format = NULL, orders = c("ymd", "dmy", "mdy"))

Arguments

x

A character or Date vector containing dates to normalize.

format

Optional format string for parsing (passed to as.Date()). If NULL (default), attempts automatic parsing via multiple common formats.

orders

Optional character vector of lubridate order specifications (e.g., c("dmy", "mdy", "ymd")). Used when format = NULL. Defaults to c("ymd", "dmy", "mdy").

Value

A character vector of dates in ISO 8601 format (YYYY-MM-DD). Unparseable dates return NA_character_ with a warning.

Details

Returns text. For matching on individual date parts (year only, year and month) use date_tokens(); to deliberately blur near-dates together use approximate_date().

When format is provided, uses as.Date(x, format) directly. When format = NULL, tries lubridate::parse_date_time() with the specified orders to handle mixed formats flexibly.

See also

Other date preparers: approximate_date(), date_tokens()

Examples

normalize_date("31.12.2023")
#> [1] "2023-12-31"
# "2023-12-31"

normalize_date("12/31/2023")
#> [1] "2023-12-31"
# "2023-12-31"

normalize_date(c("2023-01-15", "15.01.2023", "01/15/2023"))
#> [1] "2023-01-15" "2023-01-15" "2023-01-15"
# c("2023-01-15", "2023-01-15", "2023-01-15")

normalize_date("31-12-2023", format = "%d-%m-%Y")
#> [1] "2023-12-31"
# "2023-12-31"