datadr (version 0.8.4)

makeExtractable: Take a ddo/ddf HDFS data object and turn it into a mapfile

Description

Take a ddo/ddf HDFS data object and turn it into a mapfile

Usage

makeExtractable(obj)

Arguments

obj

object of class 'ddo' or 'ddf' with an HDFS connection

Examples

conn <- hdfsConn("/test/irisSplit")
  # add some data
  addData(conn, list(list("1", iris[1:10,])))
  addData(conn, list(list("2", iris[11:110,])))
  addData(conn, list(list("3", iris[111:150,])))
  # represent it as a distributed data frame
  hdd <- ddf(conn)
  # try to extract values by key (this will result in an error)
  # (HDFS can only lookup key-value pairs by key if data is in a mapfile)
  hdd[["3"]]
  # convert hdd into a mapfile
  hdd <- makeExtractable(hdd)
  # try again
  hdd[["3"]]