R/find_joining_columns.R

In healthiar: Quantifying and Monetizing Health Impacts Attributable to Exposure

#' Find joining columns

# DESCRIPTION ##################################################################
#' @description
#' This function finds columns in two data frames that have same name and identical values (excluding exceptions).- The resulting joining columns are used to dplyr::x_join data frames and add the vector to by=.

# ARGUMENTS ####################################################################
#' @param df_1 First \code{Data frame}
#' @param df_2 Second \code{Data frame}
#' @param except \code{Vector} of strings showing columns that have to be excluded although they fulfill the inclusion criteria (same name and value)

# VALUE ########################################################################
#' @returns
#' This function returns a \code{vector} of strings

#' @author Alberto Castro & Axel Luyten

#' @keywords internal


find_joining_columns <-
  function(df_1,
           df_2,
           except = NULL){

    joining_columns <-
      # First identify the columns that are common for df_1 and df_2
      dplyr::intersect(base::names(df_1),
                       base::names(df_2))|>
      # Second, the identical columns of the common ones
      # They are the columns to be used when joining data frames
      purrr::keep(~ base::identical(df_1[[.x]],
                                    df_2[[.x]]))|>
      # Finally exclude
      dplyr::setdiff(except)


  }