Skip to contents

Derive/Impute a Date from a Date Character Vector

Source: R/derive_date_vars.R
derive_vars_dt.Rd

Derive a date ('--DT') from a date character vector ('--DTC'). The date can be imputed (see date_imputation argument) and the date imputation flag ('--DTF') can be added.

Usage

derive_vars_dt(
  dataset,
  new_vars_prefix,
  dtc,
  highest_imputation = "n",
  date_imputation = "first",
  flag_imputation = "auto",
  min_dates = NULL,
  max_dates = NULL,
  preserve = FALSE
)

Arguments

dataset

Input dataset

The variables specified by the dtc argument are expected to be in the dataset.

new_vars_prefix

Prefix used for the output variable(s).

A character scalar is expected. For the date variable "DT" is appended to the specified prefix and for the date imputation flag "DTF". I.e., for new_vars_prefix = "AST" the variables ASTDT and ASTDTF are created.

dtc

The '--DTC' date to impute

A character date is expected in a format like yyyy-mm-dd or yyyy-mm-ddThh:mm:ss. Trailing components can be omitted and - is a valid "missing" value for any component.

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), "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".

flag_imputation

Whether the date imputation flag must also be derived.

If "auto" is specified and highest_imputation argument is not "n", then date imputation flag is derived.

If "date" is specified, then date imputation flag is derived.

If "none" is specified, then no date imputation flag is derived.

Permitted Values: "auto", "date" or "none"

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).

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.

preserve

Preserve day if month is missing and day is present

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

Permitted Values: TRUE, FALSE

Value

The input dataset with the date '--DT' (and the date imputation flag '--DTF'

if requested) added.

Details

In {admiral} we don't allow users to pick any single part of the date/time to impute, we only enable to impute up to a highest level, i.e. you couldn't choose to say impute months, but not days.

The presence of a '--DTF' variable is checked and if it already exists in the input dataset, a warning is issued and '--DTF' will be overwritten.

See also

Date/Time Derivation Functions that returns variable appended to dataset: derive_var_trtdurd(), derive_vars_dtm_to_dt(), derive_vars_dtm_to_tm(), derive_vars_dtm(), derive_vars_duration(), derive_vars_dy()

Examples

library(tibble)
library(lubridate)

mhdt <- tribble(
  ~MHSTDTC,
  "2019-07-18T15:25:40",
  "2019-07-18T15:25",
  "2019-07-18",
  "2019-02",
  "2019",
  "2019---07",
  ""
)

# Create ASTDT and ASTDTF
# No imputation for partial date
derive_vars_dt(
  mhdt,
  new_vars_prefix = "AST",
  dtc = MHSTDTC
)
#> # A tibble: 7 × 2
#>   MHSTDTC               ASTDT     
#>   <chr>                 <date>    
#> 1 "2019-07-18T15:25:40" 2019-07-18
#> 2 "2019-07-18T15:25"    2019-07-18
#> 3 "2019-07-18"          2019-07-18
#> 4 "2019-02"             NA        
#> 5 "2019"                NA        
#> 6 "2019---07"           NA        
#> 7 ""                    NA        

# Create ASTDT and ASTDTF
# Impute partial dates to first day/month
derive_vars_dt(
  mhdt,
  new_vars_prefix = "AST",
  dtc = MHSTDTC,
  highest_imputation = "M"
)
#> # A tibble: 7 × 3
#>   MHSTDTC               ASTDT      ASTDTF
#>   <chr>                 <date>     <chr> 
#> 1 "2019-07-18T15:25:40" 2019-07-18 NA    
#> 2 "2019-07-18T15:25"    2019-07-18 NA    
#> 3 "2019-07-18"          2019-07-18 NA    
#> 4 "2019-02"             2019-02-01 D     
#> 5 "2019"                2019-01-01 M     
#> 6 "2019---07"           2019-01-01 M     
#> 7 ""                    NA         NA    

# Impute partial dates to 6th of April
derive_vars_dt(
  mhdt,
  new_vars_prefix = "AST",
  dtc = MHSTDTC,
  highest_imputation = "M",
  date_imputation = "04-06"
)
#> # A tibble: 7 × 3
#>   MHSTDTC               ASTDT      ASTDTF
#>   <chr>                 <date>     <chr> 
#> 1 "2019-07-18T15:25:40" 2019-07-18 NA    
#> 2 "2019-07-18T15:25"    2019-07-18 NA    
#> 3 "2019-07-18"          2019-07-18 NA    
#> 4 "2019-02"             2019-02-06 D     
#> 5 "2019"                2019-04-06 M     
#> 6 "2019---07"           2019-04-06 M     
#> 7 ""                    NA         NA    

# Create AENDT and AENDTF
# Impute partial dates to last day/month
derive_vars_dt(
  mhdt,
  new_vars_prefix = "AEN",
  dtc = MHSTDTC,
  highest_imputation = "M",
  date_imputation = "last"
)
#> # A tibble: 7 × 3
#>   MHSTDTC               AENDT      AENDTF
#>   <chr>                 <date>     <chr> 
#> 1 "2019-07-18T15:25:40" 2019-07-18 NA    
#> 2 "2019-07-18T15:25"    2019-07-18 NA    
#> 3 "2019-07-18"          2019-07-18 NA    
#> 4 "2019-02"             2019-02-28 D     
#> 5 "2019"                2019-12-31 M     
#> 6 "2019---07"           2019-12-31 M     
#> 7 ""                    NA         NA    

# Create BIRTHDT
# Impute partial dates to 15th of June. No Date Imputation Flag
derive_vars_dt(
  mhdt,
  new_vars_prefix = "BIRTH",
  dtc = MHSTDTC,
  highest_imputation = "M",
  date_imputation = "mid",
  flag_imputation = "none"
)
#> # A tibble: 7 × 2
#>   MHSTDTC               BIRTHDT   
#>   <chr>                 <date>    
#> 1 "2019-07-18T15:25:40" 2019-07-18
#> 2 "2019-07-18T15:25"    2019-07-18
#> 3 "2019-07-18"          2019-07-18
#> 4 "2019-02"             2019-02-15
#> 5 "2019"                2019-06-30
#> 6 "2019---07"           2019-06-30
#> 7 ""                    NA        

# Impute AE start date to the first date and ensure that the imputed date
# is not before the treatment start date
adae <- tribble(
  ~AESTDTC, ~TRTSDTM,
  "2020-12", ymd_hms("2020-12-06T12:12:12"),
  "2020-11", ymd_hms("2020-12-06T12:12:12")
)

derive_vars_dt(
  adae,
  dtc = AESTDTC,
  new_vars_prefix = "AST",
  highest_imputation = "M",
  min_dates = exprs(TRTSDTM)
)
#> # A tibble: 2 × 4
#>   AESTDTC TRTSDTM             ASTDT      ASTDTF
#>   <chr>   <dttm>              <date>     <chr> 
#> 1 2020-12 2020-12-06 12:12:12 2020-12-06 D     
#> 2 2020-11 2020-12-06 12:12:12 2020-11-01 D     

# A user imputing dates as middle month/day, i.e. date_imputation = "mid" can
# use preserve argument to "preserve" partial dates.  For example, "2019---07",
# will be displayed as "2019-06-07" rather than 2019-06-15 with preserve = TRUE

derive_vars_dt(
  mhdt,
  new_vars_prefix = "AST",
  dtc = MHSTDTC,
  highest_imputation = "M",
  date_imputation = "mid",
  preserve = TRUE
)
#> # A tibble: 7 × 3
#>   MHSTDTC               ASTDT      ASTDTF
#>   <chr>                 <date>     <chr> 
#> 1 "2019-07-18T15:25:40" 2019-07-18 NA    
#> 2 "2019-07-18T15:25"    2019-07-18 NA    
#> 3 "2019-07-18"          2019-07-18 NA    
#> 4 "2019-02"             2019-02-15 D     
#> 5 "2019"                2019-06-30 M     
#> 6 "2019---07"           2019-06-07 M     
#> 7 ""                    NA         NA