R/stringify_frequency.R

In ClaraMarquardt/ehR: A collection of R functions designed to facilitate the interaction with and analysis of EHR data.

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#' Combine elements of a frequency table into a (character) string. 
#' 
#' 
#' @details Maintained by: Clara Marquardt
#' 
#' @export
#' @import data.table
#' 
#' @param data frequency table (table(x) output).
#' @param expl_text text which is to be appended at the end of the string (e.g. "(Percent of diagnoses)") (character). 
#' @param element_number number of rows of the frequency table which are to be included (integer) [default:10].  
#' @param sort whether to sort the frequency table (descending order) (logical - TRUE/FALSE) [default: TRUE].
#' @param item_sep symbol used to separate the elements in the string (character) [default: "//"]. 
#' @param text_col name of text column (character) [default: automatically identify column based on column types]. 
#' @param number_col name of number column (character) [default: automatically identify column based on column types]. 
#' 
#' @return formatted (character) string or data.table. 
#' 
#' @examples
#' data_raw  <- prop.table(table(dia$dia_name))*100
#' freq_string <- stringify_frequency(data=data_raw, expl_text="Percent of Principal Diagnoses (%)", element_number=5, sort=TRUE, item_sep="//", ndigit=3)
#' print(freq_string)

stringify_frequency <- function(data, expl_text, element_number=10, sort=TRUE, 
  item_sep="/", text_col=NA, number_col=NA , ndigit=3) {

  # format frequency table
  data <- data.frame(data)

  # identify columns
  if (is.na(text_col)) text_col <- names(data)[which(sapply(data,function(x) 
    class(x)[1]) %in% c("character", "factor"))]
  if (is.na(number_col)) number_col <- names(data)[which(sapply(data,function(x) 
    !(class(x)[1] %in% c("character","factor"))))]

  # order
  data[[text_col]] <- as.character(data[[text_col]] )
  if (sort==TRUE) data <- data[with(data, rev(order(get(number_col)))),]
  data <- data[1:element_number,]

  # order
  data[[number_col]] <- round(data[[number_col]], digits=ndigit)

  # generate string
  comb <- paste0(data[[text_col]], " - ", data[[number_col]],  
          " ", item_sep," ", collapse=" ")
  comb <- gsub(paste0(" ", item_sep," $"), "",comb)
  comb <- paste0(expl_text, ": ", comb)

  comb <- gsub("^[ ]*|[ ]*$", "", comb)


  # return
  return(comb)

}

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