CSIndicators (version 1.1.2)

PeriodAccumulation: Period Accumulation on multidimensional array objects

Description

Period Accumulation computes the sum (accumulation) of a given variable in a period. Providing precipitation data, two agriculture indices can be obtained by using this function:

• 'SprR', Spring Total Precipitation: The total precipitation from April 21th to June 21st.

• 'HarR', Harvest Total Precipitation: The total precipitation from August 21st to October 21st.

Usage

PeriodAccumulation(
  data,
  dates = NULL,
  start = NULL,
  end = NULL,
  time_dim = "time",
  rollwidth = NULL,
  sdate_dim = "sdate",
  frequency = "monthly",
  na.rm = FALSE,
  ncores = NULL
)

Value

A multidimensional array with named dimensions containing the accumulated data in the element data. If parameter 'rollwidth' is not used, it will have the dimensions of the input 'data' except the dimension where the accumulation has been computed (specified with 'time_dim'). If 'rollwidth' is used, it will be of same dimensions as input data.

Arguments

data

A multidimensional array with named dimensions.

dates

A multidimensional array of dates with named dimensions matching the temporal dimensions on parameter 'data'. By default it is NULL, to select aperiod 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 dimension to compute the indicator. By default, it is set to 'time'.

rollwidth

An optional parameter to indicate the number of time steps the rolling sum is applied to. If it is positive, the rolling sum is applied backwards 'time_dim', if it is negative, it will be forward it. When this parameter is NULL, the sum is applied over all 'time_dim', in a specified period. It is NULL by default.

sdate_dim

(Only needed when rollwidth is used). A character string indicating the name of the start date dimension to compute the rolling accumulation. By default, it is set to 'sdate'.

frequency

(Only needed when rollwidth is used). A character string indicating the time frequency of the data to apply the rolling accumulation. It can be 'daily' or 'monthly'. If it is set to 'monthly', values from continuous months will be accumulated; if it is 'daliy', values from continuous days will be accumulated. It is set to 'monthly' by default.

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.

Details

There are two possible ways of performing the accumulation. The default one is by accumulating a variable over a dimension specified with 'time_dim'. To chose a specific time period, 'start' and 'end' must be used. The other method is by using 'rollwidth' parameter. When this parameter is a positive integer, the cumulative backward sum is applied to the time dimension. If it is negative, the rolling sum is applied backwards.

Examples

exp <- array(rnorm(216)*200, dim = c(dataset = 1, member = 2, sdate = 3, 
            ftime = 9, lat = 2, lon = 2))
TP <- PeriodAccumulation(exp, time_dim = 'ftime')
data <- array(rnorm(5 * 3 * 214 * 2),
             c(memb = 5, sdate = 3, ftime = 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'))
dim(Dates) <- c(sdate = 3, ftime = 214)
SprR <- PeriodAccumulation(data, dates = Dates, start = list(21, 4), 
                          end = list(21, 6), time_dim = 'ftime')
HarR <- PeriodAccumulation(data, dates = Dates, start = list(21, 8), 
                          end = list(21, 10), time_dim = 'ftime')