R/sample_sizes.r

In masurp/pmmisc: Convenient functions for data transformations and reporting

#' Creates table with sample sizes and attrition rates
#' 
#' This functions binds individual numeric values (representing sample sizes) into a printable table. It is a follow-up function for \code{\link[pmmisc]{save_n}} which extracts the number of cases in a data frame.
#' 
#' @param ... Several numeric values representing sample sizes (e.g., obtained by using \code{\link[pmmisc]{save_n}}).
#' @param sample Names for the rows in the final table.
#' @param digits Number of digits that should be print (only in combination with \code{print = TRUE}).
#' @param print Logical value indicating whether the output should be formatted to fit APA-guidelines (transform varibales to character vectors).
#' @return An object of class \code{tbl_df} that can be passed to \code{\link[papaja]{apa_table}}. It contains all sample sizes that were provided as individual numeric values.
#' @examples
#' # Simple example
#' sample_sizes(100, 80, 10, print = TRUE)
#' 
#' # Realistic example
#' d <- mtcars
#' d1 <- d[1:28,]
#' d2 <- d1[1:20,]
#' 
#' n0 <- save_n(d)
#' n1 <- save_n(d1)
#' n2 <- save_n(d2)
#' 
#' sample_sizes(n0, n1, n2)
#' sample_sizes(n0, n1, n2, 
#'              sample = c("Sample 1", 
#'                         "Sample 2",
#'                         "Sample 3"),
#'              digits = 3,
#'              print = TRUE)
#' @export
sample_sizes <- function(..., 
                         sample = c("All cases",
                                    "Eligible cases",
                                    "Complete cases"),
                         digits = 1,
                         print = FALSE) {
  # dependencies
  library(dplyr)
  
  # creating table
  temp <-cbind(
    sample,
    n = unlist(list(...))
    ) %>%
    as_tibble %>%
    mutate(n = as.numeric(n),
           percent = (n/unlist(list(...))[[1]])*100)
  
  if (isTRUE(print)) {
    temp <- temp %>%
      mutate(n = printnum(n, digits = 0),
             percent = printnum(percent, digits = digits))
  }
  return(temp)
}