R/multi_join.r

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

#' Merging of up to five data sets at the same time
#' 
#' This function joins up to five data sets using the function \code{\link{dplyr}inner_join} from the package "dplyr". Each data set is individually joined with the next one. This way, several data sets of which only pairs have the same id variable can be joined. 
#' 
#' @param ... Up to five data frames that should be joined.  
#' @return A data frame.
#' @examples 
#' # Creating several data frames.
#' id <- c(1:100)
#' var1 <- runif(100, 1, 5)
#' var2 <- runif(100, 1, 5)
#' var3 <- runif(100, 1, 5)
#' data1 <- data.frame(id, var1)
#' data2 <- data.frame(id, var2)
#' data3 <- data.frame(id, var3)
#'
#' # Join all of them
#' multi_join(data1, data2, data3)
#' @export
multi_join <- function(...){
  
  # dependencies
  library(dplyr)
  
  # function
  df_list <- lapply(list(...), as.tibble)
  
  if (length(df_list) == 1) {
    message("You need to provide at least two data frames!")
  } else if (length(df_list) == 2) {
    data <- inner_join(df_list[[1]], df_list[[2]])
  } else if (length(df_list) == 3) {
    data <- df_list[[1]] %>%
      inner_join(df_list[[2]]) %>% 
      inner_join(df_list[[3]])
  } else if (length(df_list) == 4) {
    data <- df_list[[1]] %>% 
      inner_join(df_list[[2]]) %>% 
      inner_join(df_list[[3]]) %>%
      inner_join(df_list[[4]])
  } else if (length(df_list) == 5) {
    data <- df_list[[1]] %>% 
      inner_join(df_list[[2]]) %>% 
      inner_join(df_list[[3]]) %>%
      inner_join(df_list[[4]]) %>%
      inner_join(df_list[[5]])
  }
  return(data)
}