CST_Threshold {CSIndicators}

Absolute value of a relative threshold (percentile)

Description

Frequently, thresholds are defined by a percentile that may correspond to a different absolute value depending on the variable, gridpoint and also julian day (time). This function calculates the corresponding value of a percentile given a dataset.

Usage

CST_Threshold(
  data,
  threshold,
  start = NULL,
  end = NULL,
  time_dim = "time",
  memb_dim = "member",
  sdate_dim = "sdate",
  na.rm = FALSE,
  ncores = NULL
)

Arguments

data

An 's2dv_cube' object as provided function CST_Start or CST_Load in package CSTools.

threshold

A single scalar or vector indicating the relative threshold(s). It must contain values between 0 and 1.

start

An optional parameter to defined the initial date of the period to selectfrom the data by providing a list of two elements: the initial date of the period and the initial month of the period. By default it is set to NULL and the indicator is computed using all the data provided in data.

end

An optional parameter to defined the final date of the period to select from the data by providing a list of two elements: the final day of the period and the final month of the period. By default it is set to NULL and the indicator is computed using all the data provided in data.

time_dim

A character string indicating the name of the temporal dimension. By default, it is set to 'time'. More than one dimension name matching the dimensions provided in the object data$data can be specified. This dimension is required to subset the data in a requested period.

memb_dim

A character string indicating the name of the dimension in which the ensemble members are stored. When set it to NULL, threshold is computed for individual members.

sdate_dim

A character string indicating the name of the dimension in which the initialization dates are stored.

na.rm

A logical value indicating whether to ignore NA values (TRUE) or not (FALSE).

ncores

An integer indicating the number of cores to use in parallel computation.

Value

An ’s2dv_cube’ object containing the corresponding values of a percentile in the element data.

Examples

threshold <- 0.9
exp <- NULL
exp$data <- array(rnorm(5 * 3 * 214 * 2),
                 c(member = 5, sdate = 3, time = 214, lon = 2)) 
exp$attrs$Dates <- c(seq(as.Date("01-05-2000", format = "%d-%m-%Y"), 
                        as.Date("30-11-2000", format = "%d-%m-%Y"), by = 'day'),
                    seq(as.Date("01-05-2001", format = "%d-%m-%Y"), 
                        as.Date("30-11-2001", format = "%d-%m-%Y"), by = 'day'),
                    seq(as.Date("01-05-2002", format = "%d-%m-%Y"), 
                        as.Date("30-11-2002", format = "%d-%m-%Y"), by = 'day'))
dim(exp$attrs$Dates) <- c(sdate = 3, time = 214)
class(exp) <- 's2dv_cube'
exp_probs <- CST_Threshold(exp, threshold, start = list(21, 4), end = list(21, 6))