dw.spell {RGENERATEPREC}

It calculates dry/wet spell duration.

Description

It calculates dry/wet spell duration.

Usage

dw.spell(
  data,
  valmin = 0.5,
  origin = "1961-1-1",
  extract = NULL,
  month = 1:12,
  melting.df = FALSE,
  from.start = FALSE,
  only.inner = FALSE
)

Arguments

data

data frame R object containing daily precipitation time series for several gauges (one gauge time series per column).

valmin

threshold precipitation value [mm] for wet/dry day indicator.

origin

character string "yyyy-mm-dd" indicated the date of the first row of "data".

extract

string character referred to the state to be extracted, eg. "dry" or "wet"

month

integer vectors containing the considered months. Default is 1:12 (all the year).

melting.df

logical value. If it TRUE the output is melted into a data frame. Default is FALSE.

from.start

logical value. If is TRUE the spell is referenced to its first day, if it is FALSE (default) the spell is referenced to its last date.

only.inner

logical value. It is used in case extract is not NULL, if the value is TRUE, it extracts dry/wet spells completely inside the selected month period. Default is FALSE.

Value

Function returns a list of data frames containing the spell length expressed in days

Examples

 


data(trentino)

year_min <- 1961
year_max <- 1990

period <- PRECIPITATION$year>=year_min & PRECIPITATION$year<=year_max
station <- names(PRECIPITATION)[!(names(PRECIPITATION) %in% c("day","month","year"))]
prec_mes <- PRECIPITATION[period,station]  

## removing nonworking stations (e.g. time series with NA)
accepted <- array(TRUE,length(names(prec_mes)))
names(accepted) <- names(prec_mes)
for (it in names(prec_mes)) {
		 accepted[it]  <- (length(which(!is.na(prec_mes[,it])))==length(prec_mes[,it]))
}

prec_mes <- prec_mes[,accepted]
## the dateset is reduced!!! 
prec_mes <- prec_mes[,1:3]

origin <- paste(year_min,1,1,sep="-")
dw_spell <- dw.spell(prec_mes,origin=origin)
dw_spell_dry <- dw.spell(prec_mes,origin=origin,extract="dry")

hist(dw_spell_dry$T0001$spell_length)


## Single Gauging Station

prec_mes <- prec_mes[,1]

origin <- paste(year_min,1,1,sep="-")
dw_spell <- dw.spell(prec_mes,origin=origin)
dw_spell_dry <- dw.spell(prec_mes,origin=origin,extract="dry")
dw_spell_dry_start <- dw.spell(prec_mes,origin=origin,extract="dry",
	month=5:8,from.start=TRUE) ## dry spell 
	dw_spell_dry_start_2 <- dw.spell(prec_mes,origin=origin,extract="dry",
month=5:8,from.start=TRUE,only.inner=TRUE) ## dry spell 
## is referenced to the first day instead of the latest one as default. 

hist(dw_spell_dry[[1]]$spell_length)