spi: Classic standardized precipitation index (SPI)

In ErickChacon/mbsi: Model-based Standardized Index

Description

spi computes the spi index using gamlss models. It can also with work with precipitation series containing NA, 0 or only non-zero values.

Usage

spi(y, time, tscale = 1, period = 52)

Arguments

y	Usually rainfall from which to compute the SPI, but other variables like precipitation can also be used.
time	Time indexed to the values of the argument y, it can be in weeks, months, etc.
tscale	Time-scale to compute the SPI in time units. This argument is used to perform a moving average to the rainfall series before computing the SPI.
period	Numeric value representing the period to define seasonality. For example, 53 weeks, 12 months, 365 days. As it can be seen, it depends of the units of the argument time.

Details

details.

Value

A dataframe consisting of y, time, season, mu, sigma, pzero, ecdf and spi.

Author(s)

Erick A. Chacon-Montalvan

Examples

data(simrain)
spi_rain <- spi(simrain$rain, simrain$time)

# Visualize model fitting
plot(spi_rain)
# Visualize distribution of empirical cumulative density function
plot(spi_rain, which = "ecdf", binwidth = 0.05)
# Visualize extreme events
plot_extremes(spi_rain, threshold = 2)

ErickChacon/mbsi documentation built on Aug. 1, 2019, 4:47 p.m.