R/check_volumes.R

In rOpenGov/bibliographica: Bibliographic Data Analysis

#' @title Check Volumes
#' @description Pick volume information from page number field
#' @param x Page number field. Vector or factor of strings.
#' @return Volume information
#' @author Leo Lahti \email{leo.lahti@@iki.fi}
#' @references See citation("bibliographica")
#' @examples \dontrun{check_volumes("v.4, 293")}
#' @keywords utilities
check_volumes <- function (x) {

  nvol <- vtext <- NULL
  n2 <- n1 <- NULL

  # Handle some rare special cases manually
  if (all(is.na(x))) {
  
    nvol <- NA
    vtext <- NA
  
  } else if (length(grep("^v.[ ]*[0-9]+[ ]*-[ ]*[0-9]+.*$", x)) > 0) {
  
    n1 <- as.numeric(gsub("^v.[ ]*([0-9]+)[ ]*-[ ]*[0-9]+.*$", "\\1", x))
    n2 <- as.numeric(gsub("^v.[ ]*[0-9]+[ ]*-[ ]*([0-9]+).*$", "\\1", x))
    
    # Number of volumes
    nvol <- n2 - n1 + 1
 
    # Volume statement
    vtext <- paste("v.", n1, "-", n2, sep = "")

  }

  if ( is.null(vtext) ) { vtext <- "" }

  list(n = nvol, text = vtext)
 
}