aggInterval: Create Periods for Temporal Composites

Description

The creation of custom temporal aggregation levels (e.g., half-monthly, monthly) from native 16-day MODIS composites usually requires the definition of date sequences based on which the "composite_day_of_the_year" SDS is further processed. Complementing transDate(), which returns the respective start and end date only, this function creates full-year (half-)monthly or annual composite periods from a user-defined temporal range.

Usage

aggInterval(x, interval = c("month", "year", "fortnight"))

Value

A list with the following slots:

$begin: The start date(s) of each (half-)monthly timestep as Date object.
$end: Same for end date(s).
$beginDOY: Similar to $begin, but with character objects in MODIS-style date format (i.e., "%Y%j"; see strptime()).
$endDOY: Same for end date(s).

Arguments

x: Date object, see e.g. default value of 'timeInfo' in temporalComposite.
interval: character. Time period for aggregation. Currently available options are "month" (default), "year" and "fortnight" (i.e., every 1st and 15th day of the month).

Author

Florian Detsch

Examples

Run this code

dates <- do.call("c", lapply(2015:2016, function(i) {
  start <- as.Date(paste0(i, "-01-01"))
  end <- as.Date(paste0(i, "-12-31"))
  seq(start, end, 16)
}))

intervals <- c("month", "year", "fortnight")
lst <- lapply(intervals, function(i) {
  aggInterval(dates, interval = i)
}); names(lst) <- intervals

print(lst)