Usage
Date standardization
Firstly, we will demonstrate date standardization without imputation. We consider a data frame with two columns of dates in differing formats with no missing data.
bad.dates <- data.frame(
id = seq(5),
some.dates = c(
"02/05/92",
"01-04-2020",
"1996/05/01",
"2020-05-01",
"02-04-96"
),
some.more.dates = c(
"01 03 2015",
"2nd January 2010",
"01/05/1990",
"03-Dec-2012",
"02 April 2020"
)
)
knitr::kable(bad.dates)| id | some.dates | some.more.dates |
|---|---|---|
| 1 | 02/05/92 | 01 03 2015 |
| 2 | 01-04-2020 | 2nd January 2010 |
| 3 | 1996/05/01 | 01/05/1990 |
| 4 | 2020-05-01 | 03-Dec-2012 |
| 5 | 02-04-96 | 02 April 2020 |
fix_date_df() requires two arguments, df, a
data frame (or tibble) object and col.names, a character
vector containing the names of columns to be standardized. By default,
the first column of the data frame is assumed to contain row IDs. These
IDs are used if a warning or error is raised to assist the user with
locating the source of the error. The ID column can also be manually
provided via the id argument.
The output from this function is a data frame or tibble (dependent on
the object type of the the first argument, df) with the
selected date columns now standardized and belonging to the
Date class.
fixed.dates <- fix_date_df(
bad.dates,
c("some.dates", "some.more.dates")
)
knitr::kable(fixed.dates)| id | some.dates | some.more.dates |
|---|---|---|
| 1 | 1992-05-02 | 2015-03-01 |
| 2 | 2020-04-01 | 2010-01-02 |
| 3 | 1996-05-01 | 1990-05-01 |
| 4 | 2020-05-01 | 2012-12-03 |
| 5 | 1996-04-02 | 2020-04-02 |
datefixR can handle many different formats including -,
/, ., or white space separation, year-first or day-first, and month
supplied as a number, an abbreviation or full length name.
fix_date_char() is similar to fix_date_df()
but only applies to a single character object.
Localization
datefixR currently supports dates being provided in
English, Français (French), Deutsch (German), español (Spanish), and
Русский (Russian) by recognizing both names of months in these languages
and formatting customs. Expected languages do not need to be specified
and can be provided just like any other date to be standardized.
Functions in datefixR assume day-first instead of
month-first when day, month, and year are all given numerically (unless
year is given first). However, this behavior can be modified by passing
format = "mdy" to function calls.
If the month is given by name, then datefixR will
automatically detect the correct format without the format
argument needing to be specified by the user.
Date and month imputation
By default, datefixR imputes missing months as July, and
missing days of the month as the first day. As such, “1992” converts
to
The argument for defaulting to July is 1st-2nd July is halfway
through the year (on a non leap year). Therefore, assuming the year
supplied is indeed correct, the imputation has a maximum potential error
of 6 months from the true date. However, this behavior can be changed by
supplying the day.impute and month.impute
arguments with an integer corresponding to the desired day and month.
For example, day.impute = 1 and
month.impute = 1 results in the first day of January being
imputed instead which is often a more common imputation for missing date
data.
The imputation mechanism can also be modified to impute
NA if a month or day is missing by setting
day.impute or month.impute to NA.
This will also result in a warning being raised.
Finally, imputation can be prevented by setting
day.impute or month.impute to
NULL. This will result in an error being raised if the day
or month are missing respectively.
day.impute and month.impute can also be
passed to fix_date_df() for similar functionality.
Converting numeric dates
By default, if a date is given numerically (I.E no separators such as
“/”, “-”, or white space) and is more than four character long, then
this date is assumed to have been converted from R’s
numeric date format. If a Date object is converted to a
numeric object in R, the assigned value becomes the number
of days from 1970-01-01. Note that the date must still be
converted to a character object before being passed to a
datefixR function.
date <- as.numeric(as.Date("2023-01-17"))
print(date)
#> [1] 19374
fix_date_char(as.character(date))
#> [1] "2023-01-17"However if a date is converted to a numeric date in Excel, the number
of days is instead counted from 1900-01-01. If a user
expects that dates to have been converted to numerical dates in Excel,
then excel = TRUE can be passed to a datefixR
function to rectify this.
Roman numeral months 
Oracle Database can use Roman numerals to format months and this
custom is also used in some biological contexts. If dates in need of
parsing are in this format, roman.numeral = TRUE can be
passed to fix_date_char() or fix_date_df().
This implementation is currently experimental and is not guaranteed to
work alongside other date formats.