as.month {epitools}

Convert dates into months of the year for plotting epidemic curves

Description

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

Usage

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

Arguments

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

Details

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.

Value

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

Author(s)

Tomas Aragon, [e-mail], http://www.phdata.science

References

none

See Also

epitools: as.week, 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.month(dates, format = "%m/%d/%y")
aw

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