epitools (version 0.5-2)

epidate: Convert dates into multiple legible formats

Description

Convert character vector of dates into multiple legible formats.

Usage

epidate(x, format = "%m/%d/%Y", cal.dates = FALSE,
        before = 7, after = 7, sunday = TRUE)

Arguments

x

character vector of dates to be converted

format

format of character vector of dates

cal.dates

Calendar dates that contains x, starting 7 days 'before' (default) until 7 days 'after' x

before

defines lower limit of cal.dates: default is 7 days before earliest date in x

after

defines upper limit of cal.dates: default is 7 days after latest date in x

sunday

first day of the week is either Sunday (default) or Monday

Value

• dates
  dates wtih date-time class
• julian
  number of days since 1970-01-01
• mday
  day of the month: 1-31
• mon
  month of the year: 0-11
• month
  month: January, February, March, ...
• month2
  month: Jan, Feb, Mar, ...
• firstday
  first day of the week: Sunday or Monday
• week
  week of the year: 0-53
• year
  year: YYYY
• yr
  year: YY
• wday
  day of the week: 0-6
• weekday
  weekday: Monday, Tuesday, Wednesday, ...
• wkday
  weekday: Mon, Tue, Wed, ...
• yday
  day of the year: 0-365
• quarter
  quarter of the year: Q1, Q2, Q3, Q4
• cdates
  Calendar dates that contains dates
• cjulian
  Julian calendar dates

Details

Dates can come in many formats (e.g., November 12, 2001, 12Nov01, 11/12/2001, 11/12/01, 2001-11-12) and need to be converted into other formats for data analysis, graphical displays, generating reports, etc. There is tremendous flexibility in converting any character vector with sufficient information to be converted into a unique date. For complete options for the format option see strptime.

References

none

See Also

epitools: as.week DateTimeClasses to learn about date-time classes as.Date to convert character vector of dates into calendar dates with date-time class (done by epidate) strptime to convert date-time character strings into a date-time class format.POSIXlt or format.POSIXlt to convert date-time classes into character representations as.POSIXlt to convert either date-time objects or date-time character strings into a human legible date-time class (done by epidate) as.POSIXct to convert either date-time objects or date-time character strings into a continuous time date-time class (not done by epidate) weekdays, months, quarters, or julian, to convert date-time objects into weekdays, months, quarters, or julian representations, respectively (all are done by epidate)

Examples

#x <- c("12/1/03", "11/2/03", NA, "1/7/04", "1/14/04", "8/18/04")
#epidate(x, format = "\%m/\%d/\%y")
#epidate(x, format = "\%m/\%d/\%y", TRUE)
#
###convert vector of disease weeks into vector of mid-week dates
#dwk <- sample(0:53, 100, replace = TRUE)
#wk2date <- paste(dwk, "/", "Wed", sep="")
#wk2date[1:10]
#wk2date2 <- epidate(wk2date, format = "\%U/\%a")
#wk2date2$dates[1:20]