R/calculateEle121.R

In SWS-Methodology/faoswsAupus: Package to perform the AUPUS calculation.

##' Calculate Element 121 (Losses)
##' 
##' Element 121 (losses) is calculated as a simple ratio of total supply:
##' E_121 = R_121 * (total supply) / 100.
##' Values are always updated in this fashion unless the symbol for element 121
##' is not replaceable (i.e. it's an official figure).
##' 
##' @param stotal The column name of data corresponding to total supply
##' @param data The AUPUS node dataset, typically as produced by buildNodes.
##' @param aupusParam A list of running parameters to be used in pulling the data.
##' Typically, this is generated from getAupusParameter (see that function for
##' a description of the required elements).
##' 
##' @return This function returns an integer vector
##' containing the row numbers of observations which were updated.
##' However, it also has a side effect: rows within the
##' passed data.table ("data") have element 121's value and symbol updated.
##' 
##' @export
##' 

calculateEle121 = function(stotal, data, aupusParam){
    
    ## Data Quality Checks
    if(!exists("aupusParameterEnsured") || !aupusParameterEnsured)
        ensureAupusParameter(aupusParam)
    
    ## Define columns of interest using aupusParam$
    defineElementVariables(elements = 121, aupusParam = aupusParam)
    
    replaceIndex1 = data[, replaceable(get(element121Symb),
                                       get(ratio121Num) * get(stotal) / 100)]

    data[replaceIndex1,
        `:=`(c(element121Num, element121Symb),
             appendSymbol(get(ratio121Num) * get(stotal) / 100, "C"))]

    which(replaceIndex1)
}