R/top.R

In rOpenGov/bibliographica: Bibliographic Data Analysis

#' @title Identify Top Entries
#' @description Identify the top entries in a vector or for a given field in a data frame.
#' @param x data.frame, matrix, or vector 
#' @param field Field or column to check for a data.frame or matrix
#' @param n Number of top entries to show
#' @param output Output format: vector or data.frame
#' @param round Optional rounding
#' @param na.rm Logical. Remove NA before calculating the statistics.
#' @param include.rank Include ranking if the output is data.frame. Logical.
#' @return Vector of top counts, named by the corresponding entries
#' @export
#' @author Leo Lahti \email{leo.lahti@@iki.fi}
#' @references See citation("bibliographica")
#' @examples \dontrun{p <- top(df, field, 10)}
#' @keywords utilities
top <- function (x, field = NULL, n = NULL, output = "vector", round = NULL, na.rm = FALSE, include.rank = FALSE) {

  if (is.factor(x)) {
    x <- as.character(x)
  }

  if (is.vector(x)) {
    if (na.rm) {
      inds <- which(x == "NA")
      if (length(inds) > 0) {
        x[inds] <- NA
	warning(paste("Interpreting NA string as missing value NA. Removing", length(inds), "entries"))
      }
      x <- x[!is.na(x)]
    }
    s <- rev(sort(table(x)))
    N <- length(x)
  } else if (is.data.frame(x) || is.matrix(x)) {
    if (is.null(field)) {
      #warning("Indicate the selected field for the top function.")
      return(NULL)
    }

    x <- x[, field]
    if (na.rm) {
      inds <- which(x == "NA")
      if (length(inds) > 0) {
        x[inds] <- NA
	warning(paste("Interpreting NA string as missing value NA. Removing", length(inds), "entries"))
      }
      x <- x[!is.na(x)]
    }
    N <- length(x)
    s <- rev(sort(table(x)))
  }

  if (!is.null(n)) {
    s <- s[1:min(n, length(s))]
  }

  if (output == "data.frame") {
    s <- data_frame(name = names(s), n = unname(s), fraction = 100*unname(s)/N)
    if (is.null(field)) {field <- "Field"}
    names(s) <- c(field, "Entries (N)", "Fraction (%)")
    if (!is.null(round)) {
      s[,3] = round(s[,3], round)
    }
    if (include.rank) {
      s <- cbind(Rank = 1:nrow(s), s)
    } 
  }

  s

}