+
+#data: matrix of double or connection
+serialize = function(data, file, type, nb_per_chunk)
+{
+ bin_data = file(file, "ab")
+ #write data length on first call
+ nbytes = ifelse(type=="double",8,4)
+ first_write = FALSE
+ if (file.info(file)$size == 0)
+ {
+ #number of items always on 8 bytes
+ writeBin(0L, bin_data, size=8) #,endian="little")
+ first_write = TRUE
+ }
+ if (is.matrix(data))
+ {
+ writeBin(t(data), bin_data, size=nbytes)
+ data_length = ncol(data)
+ }
+ else #if (is(data, "connection"))
+ {
+ if (first_write)
+ {
+ data_line = scan(data, double(), sep=",", nlines=1)
+ writeBin(data_line, bin_data, size=nbytes)
+ data_length = length(data_line)
+ }
+ repeat
+ {
+ data_chunk = scan(data, double(), sep=",", nlines=nb_per_chunk)
+ if (length(data_chunk)==0)
+ break
+ writeBin(data_chunk, bin_data, size=nbytes)
+ }
+ }
+ if (first_write)
+ {
+ #ecrire file_size-1 / (nbytes*nbWritten) en 0 dans bin_data ! ignored == file_size
+ ignored = seek(bin_data, 0)
+ writeBin(data_length, bin_data, size=8)
+ }
+ close(bin_data)
+}
+
+#TODO: read in binary file, always same structure
+getDataFromFile(indices, file, type)
+{
+ bin_data = file(file, "rb")
+ nbytes = ifelse(type=="double",8,4)
+ data_length = readBin(bin_data,"double",1,nbytes) #,endian="little")
+ t(sapply(indices, function(i) readBin(bin_data,"double",n=data_length,size=nbytes)))
+}