R/combinecols.R

In Paul-James/pjames: Local Helper Functions

#' Combine two or more columns into one
#'
#' Takes a collection of columns as a list, a dataframe, or equal length vectors and merges them together. This is used when you want to combine 2 or more similar columns after a merge/join/rbind and the values don't overlap (if the values overlap, overlapped values will be lost). The collection can be various data types.
#'
#' @param ... A vector of columns, a list of columns, or a data.frame that you want to collect into a single column.
#' @param na.string A character vector of string(s) which are to be interpreted as \code{NA} values. Blank observations are also considered to be missing values in logical, integer, numeric, and complex fields.
#' @param returntype The data type you want the combined column to be. Choose one of, \code{'character', 'factor', 'integer', 'numeric'}.
#'
#' @keywords combine columns
#'
#' @examples
#' df <- data.frame(
#'     performingPhysio = c("jill", "jack", '', '')
#'   , operatingPhysio  = c(NA, NA, NA, "shankman")
#'   , stringsAsFactors = FALSE
#'   )
#' df$physios <- combinecols(
#'     df$performingPhysio
#'   , df$operatingPhysio
#'   , na.string  = c('', NA)
#'   , returntype = 'character'
#'   )
#' df
#'
#' asd <- data.frame(
#'     col1             = as.factor(c(1:5, rep("", 15)))
#'   , col2             = as.integer(c(rep("", 7), 8:13, rep("", 7)))
#'   , col3             = c(rep("", 15), 16:20)
#'   , stringsAsFactors = FALSE
#'   )
#'
#' qwe <- lapply(asd, function(x) x)
#'
#' asd$newCol1 <- combinecols(
#'     asd$col1
#'   , asd$col2
#'   , asd$col3
#'   , na.string  = ''
#'   , returntype = 'integer'
#'   )
#' asd$newCol2 <- combinecols(
#'     qwe
#'   , na.string  = ''
#'   , returntype = 'factor'
#'   )
#' asd
#'
#' @rdname combinecols
#' @export

combinecols <- function(
    ...
  , na.string  = NA
  , returntype = c('character', 'factor', 'integer', 'numeric')
  ){

  returntype <- match.arg(returntype)

  cols <- list(...)

  # test to see if original input was already a list
  if(class(cols[[1]]) == 'list'){
    cols <- cols[[1]]
  }

  # test to see if original input was a dataframe
  if(class(cols[[1]]) == 'data.frame'){
    cols <- lapply(cols, function(X) X)
  }

  # test for factors and set indicator
  if('factor' %in% sapply(cols, class) == TRUE){
    fac <- sapply(cols, class) %in% 'factor'
    cols[fac] <- lapply(cols[fac], as.character)
  }

  # initiate the new combined column with NA's
  new.col <- rep(NA, times = length(cols[[1]]))

  # convert the na.string's to NA
  na <- function(x, na.str = na.string){
    x[x %in% na.string] <- NA
    x
  }
  cols <- lapply(cols, na)

  # add non NA values to the combined column
  for(I in 1:length(cols)){
    new.col[!is.na(cols[[I]])] <- cols[[I]][!is.na(cols[[I]])]
  }

  if(returntype == 'factor'){ # return a factored column
    as.factor(new.col)
  } else if(returntype == 'integer'){ # return an integer column
    as.integer(new.col)
  } else if(returntype == 'numeric'){ # return a numeric column
    as.numeric(new.col)
  } else {
    new.col # return a character column
  }
}