datadr (version 0.8.5)

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

## Not run: 
#   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"]]
# ## End(Not run)