R/dfList.R

In pvsR: An R package to interact with the Project Vote Smart API for scientific research

# ' Harmonize and combine different data frames in a list
# ' 
# '  A function that harmonizes and combines different data frames in a list to one data frame.
# ' @usage dfList(l)
# ' @param l a list containing several data frames
# ' @return A data frame combining all individual data frames from the input list
# ' @examples
# ' a <- data.frame(a=c(1,2,4),b=c(5,5,6))
# ' b <- data.frame(a=c(3,4,5,6), b=c(8,8,5,4), c=c(9,4,2,1))
# ' x <- list(a,b)
# ' dfList(x)


dfList <- function(l) {
  
  # coerce df columns to character, clean data
  l <- lapply(l, FUN = function(i){
    
    for (j in names(i)) {
      
      i[,j] <- as.character(i[,j])
      i[!is.na(i[,j]) & i[,j]=="list()",j] <- NA # test this
      i[,j] <- as.character(i[,j])
      
      
    }
    
    i
    
  })
  
  if (length(l)==1) {
    
    l2 <- l
    
  } else {
    
  
  # first: extract all variable names that come up in the data frames of the list 
  
  l.names.list <- lapply(l, FUN = function(x) names(x))
  
  l.names <- do.call("c",l.names.list )
  
  l.names <- unique(l.names)
  
  
  
  # second: complete and clean each df of the list.
  
  
  l2 <- lapply(l, FUN=function(x) {
    
    # check which variable names from l.names are in x
    available <- sapply(l.names, FUN= function(i) {
      
      match(i,names(x), nomatch=0)==0
      
    })
    
    available <- data.frame(missing=available,name=names(available))
    
    # extract missing variable names
    missing <- as.character(available[which(available$missing==TRUE),"name"])
    
    # generate df with missing names (filled with NA)
    df.missing <- data.frame(matrix(NA, nrow=1, ncol=length(missing)))
    names(df.missing) <- missing
    names(df.missing) <- missing
    
    # extend existing df x with the df of missing names
    x <- data.frame(x,df.missing, check.names=FALSE)
    
    #order names according to l.names to guarantee "correct rbind"
    x <- x[,l.names]
    
    x
    
  })
  
  }
  
  # now the list is ready to be rbind to one dataframe 
  l.df <- do.call("rbind", l2)
  
  # clean the df
  
  l.df
  
  
}