lfstat (version 0.9.4)

apply.seasonal: Apply an aggregation function seasonally.

Description

Similar to the functions apply.daily, apply.monthly, apply.yearly etc. from the xts package.

Usage

apply.seasonal(x, varying, fun = function(x) min(x, na.rm = TRUE), aggregate = NULL, replace.inf = TRUE, origin = 1)

Arguments

x

an object of class xts or zoo. The time series which should get aggregated.

varying

a character vector of length one of a possibly named vector of class Date or coercible to Date. Valid character vectors are "daily", "weekly", "monthly" or "constant". If of class Date, the elements are considered as startpoints of a season. See Examples.

fun

the function used for aggregating all elements of a season.

aggregate

possibly a function used for aggregating per season.

replace.inf

should non-finite values introduced by fun be omitted?

origin

The start of the hydrological year. If set to 1 (the default) aggregation is carried out using the calendar year.

Value

Examples

 data(ngaruroro)
 ng <- as.xts(ngaruroro)

 year <- water_year(time(ng), origin = "Sept")
 ng10 <- ng[year %in% 1991:2000, ]

 # computes the annual minima (AM)
 apply.seasonal(ng10, varying = "yearly", origin = 9)

 # computes the mean annual minima (MAM)
 apply.seasonal(ng10, varying = "yearly", aggregate = mean, origin = 9)

 # computes monthly minima (AM)
 apply.seasonal(ng10, varying = "monthly", origin = 9)

 # computes minima for summer and winter separately
 # winter starts in September
 seasons <- as.Date(c("1999-09-01", "1999-11-04"))
 names(seasons) <- c("winter", "summer")
 apply.seasonal(ng10$discharge, varying = seasons, origin = 9)