AnomaliesFiltersLags: Calculate anomalies, lags and rolling windows

In greenbrown: Land Surface Phenology and Trend Analysis

Description

This function computes several time-variant statisttics of a time series like seasonal anomalies, time lagged versions of time series, and filters time series based on running windows (using rollapply.

Usage

AnomaliesFiltersLags(x, 
    funSeasonalCycle = MeanSeasonalCycle, 
    funFilter = median, 
    alignFilter = c("center", 
        "left", "right"), 
    filters = c(3, 5, 
        7, 9, 11, 13), 
    lags = -1:-7, anom = TRUE, 
    ...)

Arguments

x	univariate time series of class ts
funSeasonalCycle	a function to estimate the seasonal cycle of the time series.
funFilter	a function to filter the time series based on rolling windows.
alignFilter	specifies whether the index of the running filter results should be left- or right-aligned or centered (default) compared to the rolling window of observations. See rollapply
filters	window sizes for rolling filters to be applied. If NULL, do not apply filters.
lags	time lags to be applied for lagged time series. If NULL, do not apply lags.
anom	compute seasonal anomalies?
...	further arguments (currently not used)

Value

The function returns a multivariate time series of class 'mts' with the following columns:

• orig the original time series

• msc mean seasonal cycle as computed with funSeasonalCycle (repeated for the full time series length)

• anom anomalies releative to mean seasonal cycle

• orig.filterX rolling window result based on the original time series as computed with funFilter for the filter window size X

• anom.filterX rolling window result based on the anomaly time series as computed with funFilter for the filter window size X

• orig.lagX time lagged version of the original time series for the time lag X

• msc.lagX time lagged version of the mean seasonal cycle time series for the time lag X

• anom.lagX time lagged version of the anomaly time series for the time lag X

Author(s)

Matthias Forkel <[e-mail]> [aut, cre]

See Also

MeanSeasonalCycle

Examples

# do calculations
afl <- AnomaliesFiltersLags(ndvi)
summary(afl)

# seasonal anomalies
plot(afl[,"anom"]) 

# running median filters on original time series
plot(afl[, grep("orig.filter", colnames(afl))], plot.type="single", col=rainbow(6)) 

# running median filters on anomalies
plot(afl[, grep("anom.filter", colnames(afl))], plot.type="single", col=rainbow(6)) 

# lagged versions of original time series
plot(window(afl[, grep("orig.lag", colnames(afl))], start=c(1995, 1), 
   end=c(2000, 12)), plot.type="single", col=rainbow(7), type="l") 

# lagged versions of anomaly time series
plot(afl[, grep("anom.lag", colnames(afl))], plot.type="single", col=rainbow(7)) 

greenbrown documentation built on Dec. 18, 2020, 3:02 p.m.