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Convert a Date Character Vector into a Datetime Object

Source: R/derive_vars_dtm.R
convert_dtc_to_dtm.Rd

Convert a date character vector (usually '--DTC') into a Date vector (usually '--DTM').

Usage

convert_dtc_to_dtm(
  dtc,
  highest_imputation = "h",
  date_imputation = "first",
  time_imputation = "first",
  min_dates = NULL,
  max_dates = NULL,
  preserve = FALSE
)

Arguments

dtc

The '--DTC' date to convert.

highest_imputation

Highest imputation level

The highest_imputation argument controls which components of the DTC value are imputed if they are missing. All components up to the specified level are imputed.

If a component at a higher level than the highest imputation level is missing, NA_character_ is returned. For example, for highest_imputation = "D" "2020" results in NA_character_ because the month is missing.

If "n" is specified, no imputation is performed, i.e., if any component is missing, NA_character_ is returned.

If "Y" is specified, date_imputation should be "first" or "last" and min_dates or max_dates should be specified respectively. Otherwise, NA_character_ is returned if the year component is missing.

Permitted Values: "Y" (year, highest level), "M" (month), "D" (day), "h" (hour), "m" (minute), "s" (second), "n" (none, lowest level)

date_imputation

The value to impute the day/month when a datepart is missing.

A character value is expected, either as a

  • format with month and day specified as "mm-dd": e.g. "06-15" for the 15th of June (The year can not be specified; for imputing the year "first" or "last" together with min_dates or max_dates argument can be used (see examples).),

  • or as a keyword: "first", "mid", "last" to impute to the first/mid/last day/month. If "mid" is specified, missing components are imputed as the middle of the possible range:

    • If both month and day are missing, they are imputed as "06-30" (middle of the year).

    • If only day is missing, it is imputed as "15" (middle of the month).

The argument is ignored if highest_imputation is less then "D".

time_imputation

The value to impute the time when a timepart is missing.

A character value is expected, either as a

  • format with hour, min and sec specified as "hh:mm:ss": e.g. "00:00:00" for the start of the day,

  • or as a keyword: "first","last" to impute to the start/end of a day.

The argument is ignored if highest_imputation = "n".

min_dates

Minimum dates

A list of dates is expected. It is ensured that the imputed date is not before any of the specified dates, e.g., that the imputed adverse event start date is not before the first treatment date. Only dates which are in the range of possible dates of the dtc value are considered. The possible dates are defined by the missing parts of the dtc date (see example below). This ensures that the non-missing parts of the dtc date are not changed. A date or date-time object is expected. For example

impute_dtc_dtm(
  "2020-11",
  min_dates = list(
   ymd_hms("2020-12-06T12:12:12"),
   ymd_hms("2020-11-11T11:11:11")
  ),
  highest_imputation = "M"
)

returns "2020-11-11T11:11:11" because the possible dates for "2020-11" range from "2020-11-01T00:00:00" to "2020-11-30T23:59:59". Therefore "2020-12-06T12:12:12" is ignored. Returning "2020-12-06T12:12:12" would have changed the month although it is not missing (in the dtc date).

For date variables (not datetime) in the list the time is imputed to "00:00:00". Specifying date variables makes sense only if the date is imputed. If only time is imputed, date variables do not affect the result.

max_dates

Maximum dates

A list of dates is expected. It is ensured that the imputed date is not after any of the specified dates, e.g., that the imputed date is not after the data cut off date. Only dates which are in the range of possible dates are considered. A date or date-time object is expected.

For date variables (not datetime) in the list the time is imputed to "23:59:59". Specifying date variables makes sense only if the date is imputed. If only time is imputed, date variables do not affect the result.

preserve

Preserve lower level date/time part when higher order part is missing, e.g. preserve day if month is missing or preserve minute when hour is missing.

For example "2019---07" would return "2019-06-07 if preserve = TRUE (and date_imputation = "mid").

Permitted Values: TRUE, FALSE

Value

A datetime object

Details

Usually this computation function can not be used with %>%.

See also

Date/Time Computation Functions that returns a vector: compute_age_years(), compute_dtf(), compute_duration(), compute_tmf(), convert_date_to_dtm(), convert_dtc_to_dt(), impute_dtc_dt(), impute_dtc_dtm()

Examples

convert_dtc_to_dtm("2019-07-18T15:25:00")
#> [1] "2019-07-18 15:25:00 UTC"
convert_dtc_to_dtm("2019-07-18T00:00:00") # note Time = 00:00:00 is not printed
#> [1] "2019-07-18 UTC"
convert_dtc_to_dtm("2019-07-18")
#> [1] "2019-07-18 UTC"