HadoopStreaming (version 0.2)

hsKeyValReader: Reads key value pairs

Description

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.

Usage

hsKeyValReader(file = "", chunkSize = -1, skip = 0, sep = "\t",FUN = function(k, v) cat(paste(k, v, sep = ": "), sep = "\n"))

Arguments

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.

Value

No return value.

Examples

  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)