R filtering out a subset

Question

I have a data.frame A and a data.frame B which contains a subset of A

How can I create a data.frame C which is data.frame A with data.frame B excluded? Thanks for your h

Answer 1

This is not the fastest and is likely to be very slow but is an alternative to mplourde's that takes into account the row data and should work on mixed data which flodel critiqued. It relies on the paste2 function from the qdap package which doesn't exist yet as I plan to release it within the enxt month or 2:

Paste 2 function:

paste2 <- function(multi.columns, sep=".", handle.na=TRUE, trim=TRUE){

    if (trim) multi.columns <- lapply(multi.columns, function(x) {
            gsub("^\\s+|\\s+$", "", x)
        }
    )

    if (!is.data.frame(multi.columns) & is.list(multi.columns)) {
        multi.columns <- do.call('cbind', multi.columns)
      }

    m <- if(handle.na){
                 apply(multi.columns, 1, function(x){if(any(is.na(x))){
                       NA
                 } else {
                       paste(x, collapse = sep)
                 }
             }
         )   
         } else {
          apply(multi.columns, 1, paste, collapse = sep)
    }
    names(m) <- NULL
    return(m)
}

# Flodel's mixed data set:

A <- data.frame(x = 1:4, y = as.character(1:4)); B <- A[1:2, ]

# My approach:

A[!paste2(A)%in%paste2(B), ]