bench.r

library(microbenchmark)

charBinaryMat <- function(listOfValues, fill = NA) {
  lev <- sort(unique(unlist(listOfValues, use.names = FALSE)))
  m <- matrix(fill, nrow = length(listOfValues), ncol = length(lev))
  colnames(m) <- lev
  for (i in 1:nrow(m)) {
    m[i, listOfValues[[i]]] <- 1
  }
  m
}

reverseIn <- function(vector, value) {
  return(value %in% vector)
}

buildCategoryMatrix <- function(valueVector) {
  allClasses <- c()
  for(classVec in unique(valueVector)) {
    allClasses <- unique(c(allClasses,
      strsplit(classVec, " ", fixed=TRUE)[[1]]))
  }
  
  resMatrix <- matrix(ncol=0, nrow=length(valueVector))
  splitValues <- strsplit(valueVector, " ", fixed=TRUE)
  
  for(cat in allClasses) {
    if(cat=="") {
      catIsPart <- (valueVector == "")
    } else {
      catIsPart <- sapply(splitValues, reverseIn, cat)
    }
    resMatrix <- cbind(resMatrix, catIsPart)
  }
  colnames(resMatrix) <- allClasses
  
  return(resMatrix)
}

CBM <- function(str) {
  charBinaryMat(strsplit(str, " ", fixed=TRUE), fill = 0)
}
BCM <- function(str) {
  buildCategoryMatrix(str)*1L
}
Sapply <- function(str) {
  y <- unique( unlist( strsplit( str , " " ) ) )
  out <- t(sapply(str, function(x) y %in% unlist(strsplit(x , " " )),
    USE.NAMES = FALSE )) * 1L
  colnames(out) <- y
  out
}

had <- function(x) {
  lines <- strsplit(x, " ", fixed = TRUE)
  
  all <- sort(unique(unlist(lines)))
  
  t(vapply(lines, "%in%", x = all, numeric(length(all))))  
}


set.seed(1)
A = sample(10, 1000, replace = TRUE)
str <- sapply(seq_along(A), function(x)
  paste(sample(LETTERS[1:10], A[x]), collapse = " "))
head(str)

microbenchmark(CBM(str), BCM(str), Sapply(str), had(str), times=20)
# Unit: milliseconds
#         expr       min        lq    median        uq       max neval
#     CBM(str)  2.780421  2.901480  2.957426  3.091195  9.443014    20
#     BCM(str) 42.221266 44.834562 45.091333 46.691666 49.844484    20
#  Sapply(str) 18.727119 19.106317 19.271673 20.679960 31.284702    20
#     had(str)  3.139086  3.300337  3.404033  3.452204  5.381122    20