AccumulationExceedingThreshold {CSIndicators}R Documentation

Accumulation of a variable when Exceeding (not exceeding) a Threshold

Description

The accumulation (sum) of a variable in the days (or time steps) that the variable is exceeding (or not exceeding) a threshold during a period. The threshold provided must be in the same units than the variable units, i.e. to use a percentile as a scalar, the function Threshold or QThreshold may be needed. Providing mean daily temperature data, the following agriculture indices for heat stress can be obtained by using this function:

Usage

AccumulationExceedingThreshold(
  data,
  threshold,
  op = ">",
  diff = FALSE,
  dates = NULL,
  start = NULL,
  end = NULL,
  time_dim = "time",
  na.rm = FALSE,
  ncores = NULL
)

Arguments

data

a multidimensional array with named dimensions.

threshold

a multidimensional array with named dimensions in the same units as parameter 'data' and with the common dimensions of the element 'data' of the same length.

op

a opartor '>' (by default), '<', '>=' or '<='.

diff

a logical value indicating whether to accumulate the difference between data and threshold (TRUE) or not (FALSE by default).

dates

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.

start

an optional parameter to defined 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 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 function to compute the indicator. By default, it is set to 'ftime'. More than one dimension name matching the dimensions provided in the object data$data can be specified.

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

A multidimensional array with named dimensions.

Examples

# Assuming data is already (tasmax + tasmin)/2 - 10
data <- array(rnorm(5 * 3 * 214 * 2, mean = 25, sd = 3),
                   c(memb = 5, sdate = 3, time = 214, lon = 2)) 
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'))
GDD <- AccumulationExceedingThreshold(data, threshold = 0, start = list(1, 4),
                                     end = list(31, 10))

[Package CSIndicators version 0.0.1 Index]