This function will automatically detect possible date format. Users can choose to either reformat the date or report the datetime format detected.
Identifies the likely date format used in character strings and optionally converts these strings to Date objects. This utility is intended to support pre-processing of timestamp data with varied or unknown formatting. When ambiguity arises (e.g., day-month versus month-day ordering), the function defaults to the first compatible format unless explicitly guided by a delimiter or by manual correction.
Arguments
- DT
A character vector containing date or date-time strings.
- as.date
Logical. If TRUE (default), returns converted Date objects. If FALSE, returns the detected format string (e.g.,
"%d/%m/%Y").- Delim
Optional. A single character (e.g.,
".","-", or"/") to override default date delimiters. Requited when input strings may contain nonstandard separators (e.g.,"$","~").
Value
If as.date = TRUE, returns a vector of class Date.
If as.date = FALSE, returns a character string representing the
detected format. When multiple formats coexist or no valid format is
detected, warnings are issued and default behavior is applied.
If no format matches, returns NA and issues a warning.
Examples
# Consistent format across all strings
DT <- c ("2017/05/02", "2000/02/28", "1970/01/02")
DateFormat (DT, as.date = FALSE) # returns parsed Date vector
#> [1] "%Y/%m/%d"
if (FALSE) { # \dontrun{
# Mixed formats within a vector
DT <- c (
"2017/05/02", "2000.Feb.28", "1970-11-02",
"January 01, 2025", "December 12, 1980"
)
lapply (DT, DateFormat) # element-wise parsing
### We expect that many of these format will not work because they contain
### text
DT <- c (
"2017/05/02", "2000.02.28", "1970-11-02",
"01, 01, 2025", "12, 12, 1980"
)
# Recommended usage for mixed formats:
lapply (DT, DateFormat, Delim = ",") # element-wise parsing
for (x in DT) {
print (DateFormat (x, Delim = ","))
} # displays format/warning per entry
# Avoid using sapply, because it will convert them into numeric form
sapply (DT, DateFormat)
} # }