| hsKeyValReader {HadoopStreaming} | R Documentation |
Uses scan to read in chunkSize lines at a time, where each line
consists of a key string and a value string. The first skip
lines of input are skipped. Each group of key/value pairs are passed
to FUN as a character vector of keys and character vector of values.
hsKeyValReader(file = "", chunkSize = -1, skip = 0, sep = "\t",FUN = function(k, v) cat(paste(k, v, sep = ": "), sep = "\n"))
file |
A connection object or a character string, as in scan. |
chunkSize |
The (maximal) number of lines to read at a time. The default is -1, which specifies that the whole file should be read at once. |
skip |
Number of lines to ignore at the beginning of the file |
FUN |
A function that takes a character vector as input |
sep |
The character separating the key and the value strings. |
No return value.
David S. Rosenberg. <drosen@sensenetworks.com>
printFn <- function(k,v) {
cat('A chunk:\n')
cat(paste(k,v,sep=': '),sep='\n')
}
str <- "key1\tval1\nkey2\tval2\nkey3\tval3\n"
cat(str)
con <- textConnection(str, open = "r")
hsKeyValReader(con,chunkSize=2,FUN=printFn)
close(con)
con <- textConnection(str, open = "r")
hsKeyValReader(con,FUN=printFn)
close(con)