Parses Swedish registry dates that may have varying precision (year only, year-month, or full date) and converts them to proper Date objects. Handles common Swedish registry date formats and missing date patterns.
Usage
parse_swedish_date(
date_string,
default_month_day = "0701",
default_day = "15",
na_strings = c("", "NA", "9999", "99999999")
)Arguments
- date_string
Character vector of dates in Swedish registry format
- default_month_day
Character string for default month-day when only year is provided (default: "0701" for July 1st)
- default_day
Character string for default day when only year-month is provided (default: "15" for 15th)
- na_strings
Character vector of strings to treat as NA (default: c("", "NA", "9999", "99999999"))
Details
Swedish registry dates often come in different formats:
4 characters (YYYY): Only year known - adds default_month_day
6 characters (YYYYMM): Year and month known - adds default_day
8 characters (YYYYMMDD): Full date known - uses as-is
Special handling:
"0000" endings are replaced with default_month_day
"00" endings are replaced with default_day
Invalid dates return NA with warnings
Examples
# Different date formats
dates <- c("2020", "202003", "20200315", "19990000", "199900", "19990600", "1989-01-01", "")
parse_swedish_date(dates)
#> [1] "2020-07-01" "2020-03-15" "2020-03-15" "1999-07-01" "1999-07-01"
#> [6] "1999-06-15" "1989-01-01" NA
# Custom defaults
parse_swedish_date(dates, default_month_day = "0101", default_day = "01")
#> [1] "2020-01-01" "2020-03-01" "2020-03-15" "1999-01-01" "1999-01-01"
#> [6] "1999-06-01" "1989-01-01" NA