R/clean_text.R

In UBC-MDS/rlyrics: Downloads, cleans and creates wordcloud of lyrics

#' Cleans the raw text into human readable text.
#'
#' @param text A text to clean.
#' @return 'text' output without special characters, html_tags, #tags, contaction words, stop-words and convert everything to lower case
#' @export
#'
#' @examples
#' text <- "Early optimization is the root of all evil!"
#' clean_text(text)
#> [1] "early optimization root evil"

clean_text <- function(text) {

    # check input types
    if(!is.character(text)){
        stop("Text should be a variable of type string.")
    }

    # check for blank string
    if(stringr::str_length(trimws(text)) == 0 ){
        stop("Blank text input")
    }

    # Remove everything inside []
    temp <- gsub("\\[[^][]*]"," ",text)
    # Add Space before capital letter
    temp <- gsub("([a-z])([A-Z])", "\\1 \\2", temp)
    # Remove the word Lyrics
    temp <- gsub(" Lyrics ", " ", temp)
    # Lowercase
    temp <- tolower(temp)
    # replacing contraction words
    temp <- textclean::replace_contraction(temp)
    # removing punctuation marks
    temp <- gsub('[[:punct:]]', '', temp)
    # removing stopwords special charaters
    temp <- tm::removeWords(temp, tm::stopwords("en"))
    # removing special charaters
    temp <- stringr::str_replace_all(temp,"[^a-zA-Z\\s]", " ")
    # removing extra spaces
    temp <- stringr::str_replace_all(temp,"[\\s]+", " ")

    return(temp)
}