as.month: Convert dates into months of the year for plotting epidemic...
In epitools: Epidemiology Tools

Description Usage Arguments Details Value Author(s) References See Also Examples

Converts dates into months of the year (1-12); but also creates range of calendar months that can be used to plot an epidemic curve

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as.month(x, format = "%Y-%m-%d",
         min.date, max.date, before = 31, after = 31,
         origin = as.Date("1970-01-01"), abbreviate = TRUE)

`x`	character vector of dates
`format`	date format of `x`; default is of form "2004-08-10"
`min.date`	[optional] minimum calendar date for plotting x-axis of an epidemic curve; should be of the form of "2004-08-10"; if no date is specified, then several days are subtracted from the minimum date in `x` as specified by the `before` option
`max.date`	[optional] maximum calendar date for plotting x-axis of an epidemic curve plot; should be f the form of "2004-08-10"; if no date is specified, then several days are added to the maximum date in `x` as specified by the `after` option
`before`	if `min.date` is not specified, then these number of days are subtracted from the minimum date in `x` for plotting minimum calendar date for epidemic curve
`after`	if `max.date` is not specified, then these number of days are added to the maximum date in `x` for plotting maximum calendar date for epidemic curve
`origin`	allows user to specify an alternative origin for Julian dates that are generated by this function (default = "1970-01-01")
`abbreviate`	abbreviate month names to Jan, Feb, Mar, etc.; often used for labeling plots

This function converts dates to months (1-12). In addition, a range of calendar months are generated that can be used to plot the x-axis of an epidemic curve.

Returns a list of the following:

`$dates`	input dates are converted to standard calendar date format
`$mon`	month of the year (1-12)
`$month`	month of the year (Jan, Feb, Mar, ...)
`$stratum`	the Julian date for the mid-month day of the `$mon` value
`$stratum2`	the Julian date for the mid-month day of the `$mon` value converted to a factor with levels determined by the Julian dates (`$cstratum`)used to plot an epidemic curve
`$stratum3`	the mid-month day of the `$mon` value converted to standard calendar dates
`$cmon`	the month of the year (1-12) used for plotting the x-axis of the epidemic curve
`$cmonth`	the months (Jan, Feb, Mar, ...) for the calendar dates used for plotting the x-axis of an epidemic curve
`$cstratum`	the Julian date for the mid-month day of the `$cmonth` value used for plotting the x-axis of an epidemic curve
`$cstratum2`	the standard calendar date for the mid-month day of the `$cmonth` value used for plotting the x-axis of an epidemic curve
`$cmday`	the day of the mon (1-31) for the calendar dates used for plotting the x-axis of an epidemic curve
`$cyear`	the years (e.g., 1996, 2001, ...) for the calendar dates used for plotting the x-axis of the epidemic curve

Tomas Aragon, aragon@berkeley.edu, http://www.phdata.science

none

epitools: as.week, epicurve.dates

as.Date, strptime, DateTimeClasses

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.month(dates, format = "%m/%d/%y")
aw

aw2 <- as.month(dates, format = "%m/%d/%y", min.date="2003-01-01")
aw2