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)