epitools (version 0.5-2)

as.hour: Convert date-time object into hour units

Description

Convert date-time object into hour or half-hour units

Usage

as.hour(x, mindt, maxdt, half.hour = FALSE)

Arguments

x

Date-time object in standard format: for example, "2004-12-23 08:27:00", "2004-12-23 08:27", "2004-12-23"

mindt

[required] Date-time object in standard format that will form the lower boundary of the hour or half-hour time categories. mindt must less than or equal to the minimum value in x, and must be rounded off to the nearst hour for

maxdt

[required] Date-time object in standard format that will form the upper boundary of the hour or half-hour time categories. maxdt must greater than or equal to the minimum value in x, and must be rounded off to the nearst hour

half.hour

Set to TRUE for half-hour categories.

Value

• $ct
  Date-time object that contains the number of seconds since the beginning of 1970 as a numeric vector and produced by as.POSIXct. You can use as.POSIXlt to convert this output in human legible (already done by this function).
• $sec
  seconds
• $min
  minutes
• $hour
  hours (0-23)
• $hour12
  hours (1-12)
• $stratum
  number of hours or 1/2 hours since beginning of 1970
• $stratum2
  factor (categorical variable) with number of hours of 1/2 hours since beginning of 1970 using $cstratum as the levels
• $stratum3
  factor (categorical variable) in standard date-time format indicating number of hours or 1/2 hours since beginning of 1970 using $cstratum2 as the levels
• $cstratum
  levels for creating $stratum2 factor
• $cstratum2
  levels for creating $stratum3 factor
• $csec
  seconds from $cstratum2
• $cmin
  minutes from $cstratum2
• $chour
  hours from $cstratum2 in 24-hour format
• $chour12
  hours from $cstratum2 in 12-hour format
• $campm
  corresponding 'AM' or 'PM' for $chour12
• $campm2
  corresponding 'am' or 'pm' for $chour12
• $cweekday
  day of the week for $cstratum2
• $cwkday
  abbreviated day of the week for $cstratum2
• $cmday
  day of the month for $cstratum2
• $cmonth
  month for $cstratum2
• $cmon
  abbreviated month for $cstratum2
• $cyear
  year for $cstratum2
• $half.hour
  FALSE (default) for 1-hour categories; TRUE for 1/2-hour categories

Details

This function (1) converts standard date-time objects into 1-hour or 1/2-hour categories, and (2) generates levels for range of values that that the new 1-hour or 1/2-hour categories can take. These levels are use for converting x into a factor and for providing names for labeling the x-axis in plot. This function is used by epicurves.hours.

References

none

See Also

epitools: as.month, epicurve.dates as.Date, strptime, DateTimeClasses

Examples

dates <- c("1/1/04", "1/2/04", "1/3/04", "1/4/04", "1/5/04",
"1/6/04", "1/7/04", "1/8/04", "1/9/04", "1/10/04", NA, "1/12/04",
"1/14/04", "3/5/04", "5/5/04", "7/6/04", "8/18/04", "12/13/05",
"1/5/05", "4/6/05", "7/23/05", "10/3/05")
aw <- as.week(dates, format = "%m/%d/%y")
aw

aw2 <- as.week(dates, format = "%m/%d/%y", sunday= FALSE)
aw2

aw3 <- as.week(dates, format = "%m/%d/%y", min.date="2003-01-01")
aw3