AbsToProbs: Transform ensemble forecast into probabilities

In CSIndicators: Climate Services' Indicators Based on Sub-Seasonal to Decadal Predictions

Transform ensemble forecast into probabilities

Description

The Cumulative Distribution Function of a forecast is used to obtain the probabilities of each value in the ensemble. If multiple initializations (start dates) are provided, the function will create the Cumulative Distribution Function excluding the corresponding initialization.

Usage

AbsToProbs(
  data,
  dates = NULL,
  start = NULL,
  end = NULL,
  time_dim = "time",
  memb_dim = "member",
  sdate_dim = "sdate",
  ncores = NULL
)

Arguments

data	A multidimensional array with named dimensions.
dates	An optional parameter containing a vector of dates or a multidimensional array of dates with named dimensions matching the dimensions on parameter 'data'. By default it is NULL, to select a period this parameter must be provided. All common dimensions with 'data' need to have the same length.
start	An optional parameter to define the initial date of the period to select from 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 define 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.
sdate_dim	A character string indicating the name of the dimension in which the initialization dates are stored.
ncores	An integer indicating the number of cores to use in parallel computation.

Value

A multidimensional array with named dimensions containing the probabilites in the element data.

Examples

exp <- array(rnorm(216), dim = c(dataset = 1, member = 2, sdate = 3, 
                                time = 9, lat = 2, lon = 2))
exp_probs <- AbsToProbs(exp)
data <- array(rnorm(5 * 3 * 61 * 1),
             c(member = 5, sdate = 3, time = 61, lon = 1)) 
Dates <- c(seq(as.Date("01-05-2000", format = "%d-%m-%Y"), 
              as.Date("30-06-2000", format = "%d-%m-%Y"), by = 'day'),
          seq(as.Date("01-05-2001", format = "%d-%m-%Y"), 
              as.Date("30-06-2001", format = "%d-%m-%Y"), by = 'day'),
          seq(as.Date("01-05-2002", format = "%d-%m-%Y"), 
              as.Date("30-06-2002", format = "%d-%m-%Y"), by = 'day'))
dim(Dates) <- c(time = 61, sdate = 3)
exp_probs <- AbsToProbs(data, dates = Dates, start = list(21, 4), 
                       end = list(21, 6))

CSIndicators documentation built on Nov. 20, 2023, 5:07 p.m.