SPI.calc: Calculate Standardized Precipitation Index, SPI
In zejiang-unsw/WASP_1.0.0: WAvelet System Prediction

Description Usage Arguments Value Examples

Calculate Standardized Precipitation Index, SPI

1	SPI.calc(prec.zoo, sc = 24, method = "mle")

`prec.zoo`	A zoo series contain date and rainfall vector/matrix.
`sc`	The accumulation period in months. Commonly 6, 12, 24, 36, and 48 months.
`method`	A character string coding for the fitting method: "mle" for 'maximum likelihood estimation', "mme" for 'moment matching estimation', "qme" for 'quantile matching estimation' and "mge" for 'maximum goodness-of-fit estimation'.

A matrix of time sereis.

data(rain.mon)
data(SPI.12)
##compute SPI
SPI <- SPI.calc(window(rain.mon, start=c(1949,1), end=c(2009,12)),sc=12)

##compare with sample data set SPI.12
par(mfrow=c(3,5))
for(i in 1:ncol(SPI)) plot(SPI[,i],SPI.12[,i])