R/GuessLanguagePipe.R

In miferreiro/bdp4R: Big Data Preprocessing For R

#' @title Class to guess the language
#' @description Class to guess the language by using language detector of library
#' cld2. Optionally, it is possible to choose the language provided by twitter.
#' @docType class
#' @usage GuessLanguagePipe$new(propertyName = "language",
#'                       alwaysBeforeDeps = list("StoreFileExtensionPipe",
#'                                               "TargetAssigningPipe",
#'                                               "StripHTMLPipe"),
#'                       notAfterDeps = list())
#' @param propertyName  (character) Name of the property associated with the pipe.
#' @param alwaysBeforeDeps (list) The dependences alwaysBefore (pipes that must
#' be executed before this one).
#' @param notAfterDeps (list) The dependences notAfter (pipes that cannot be
#' executed after this one).
#' @details The pipe will invalidate the instance if the language of the data
#' can not be detect.
#'
#' To obtain the language of the tweets, it will be verified that there is a
#' json file with the information stored in memory.
#'
#' @section Inherit:
#' This class inherits from \code{\link{PipeGeneric}} and implements the
#' \code{pipe} abstract function.
#' @section Methods:
#' \itemize{
#' \item{\bold{pipe}}{
#' Function that preprocesses the instance to obtain the language of the data.
#' \itemize{
#' \item{\emph{Usage}}{
#'
#' \code{pipe(instance, languageTwitter = TRUE)}
#' }
#' \item{\emph{Value}}{
#'
#' The instance with the modifications that have occurred in the pipe.
#' }
#' \item{\emph{Arguments}}{
#' \itemize{
#' \item{\strong{instance}}{
#' (Instance) Instance to preproccess.
#' }
#' \item{\strong{languageTwitter}}{
#' (logical) Indicates whether for the instances of type twtid the language that
#' returns the api is obtained or the detector is applied.
#' }
#' }
#' }
#' }
#' }
#'
#' \item{\bold{getLanguage}}{
#' Function that guess the language of data.
#' \itemize{
#' \item{\emph{Usage}}{
#'
#' \code{getLanguage(data)}
#' }
#' \item{\emph{Value}}{
#'
#' The language guesser. Format: see ISO 639-3:2007.
#' }
#' \item{\emph{Arguments}}{
#' \itemize{
#' \item{\strong{data}}{
#' (character) Text to guess the language.
#' }
#' }
#' }
#' }
#' }
#' }
#'
#' @seealso \code{\link{PipeGeneric}}, \code{\link{Instance}}
#'
#' @import R6 cld2 pipeR
#' @importFrom rjson fromJSON
#' @export GuessLanguagePipe

GuessLanguagePipe <- R6Class(

  "GuessLanguagePipe",

  inherit = PipeGeneric,

  public = list(

    initialize = function(propertyName = "language",
                          alwaysBeforeDeps = list("StoreFileExtensionPipe",
                                                  "TargetAssigningPipe",
                                                  "StripHTMLPipe"),
                          notAfterDeps = list()) {

      if (!"character" %in% class(propertyName)) {
        stop("[GuessLanguagePipe][initialize][Error]
                Checking the type of the variable: propertyName ",
                  class(propertyName))
      }

      if (!"list" %in% class(alwaysBeforeDeps)) {
        stop("[GuessLanguagePipe][initialize][Error]
                Checking the type of the variable: alwaysBeforeDeps ",
                  class(alwaysBeforeDeps))
      }
      if (!"list" %in% class(notAfterDeps)) {
        stop("[GuessLanguagePipe][initialize][Error]
                Checking the type of the variable: notAfterDeps ",
                  class(notAfterDeps))
      }

      super$initialize(propertyName, alwaysBeforeDeps, notAfterDeps)
    },

    pipe = function(instance, languageTwitter = TRUE) {

      if (!"Instance" %in% class(instance)) {
        stop("[GuessLanguagePipe][pipe][Error]
                Checking the type of the variable: instance ",
                  class(instance))
      }

      instance$addFlowPipes("GuessLanguagePipe")

      if (!instance$checkCompatibility("GuessLanguagePipe", self$getAlwaysBeforeDeps())) {
        stop("[GuessLanguagePipe][pipe][Error] Bad compatibility between Pipes.")
      }

      instance$addBanPipes(unlist(super$getNotAfterDeps()))

      if (languageTwitter
            && instance$getSpecificProperty("extension") %in% "twtid") {

        cachePath <- read.ini(Bdp4R[["private_fields"]][["configurationFilePath"]])$cache$pathCacheTwtid

        if (file.exists(paste(cachePath, "/_",
                                  instance$getSpecificProperty("target"),
                                    "_/",
                                      instance$getId(),
                                        ".json",
                                          sep = ""))) {

          path <- paste(cachePath,"/_",
                          instance$getSpecificProperty("target"),
                            "_/",
                              instance$getId(),
                                ".json",
                                  sep = "")

          dataFromJsonFile <- fromJSON(file = path)

          if (!is.na(dataFromJsonFile[["lang"]]) &&
                !is.null(dataFromJsonFile[["lang"]])
                  && dataFromJsonFile[["lang"]] != "") {

            langTwitter <- dataFromJsonFile[["lang"]]

            instance$addProperties(langTwitter,super$getPropertyName())

            if (is.null(instance$getSpecificProperty("language"))) {

              message <- c( "The file: " , instance$getPath() , " has a NULL twitter language")

              instance$addProperties(message, "reasonToInvalidate")

              cat("[GuessLanguagePipe][pipe][Warning] ", message, " \n")

              instance$invalidate()

              return(instance)
            }

            return(instance)
          }
        }
      }

      instance$getData() %>>%
        self$getLanguage() %>>%
          {instance$addProperties(.,super$getPropertyName())}

      if (is.na(instance$getSpecificProperty("language"))) {
        message <- c( "The file: " , instance$getPath() , " has a null language")

        instance$addProperties(message, "reasonToInvalidate")

        cat("[GuessLanguagePipe][pipe][Warning] ", message, " \n")

        instance$invalidate()

        return(instance)
      }

      return(instance)
    },

    getLanguage = function(data) {

      if (!"character" %in% class(data)) {
        stop("[GuessLanguagePipe][getLanguage][Error]
                Checking the type of the variable: data ",
                  class(data))
      }

      langStandardize <- detect_language(data, plain_text = TRUE)

      return(langStandardize)
    }
  )
)