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rmapreducedatasetdataformat

change mapreduce output format using R

I faced a problem.When I got the mapreduce output ,the result is {key :value} format.

For example the mapreduce output is:

key value

a   [111,112,114]

b   [111,122,134]

c   [125]

so I want to change format like this:

a  111

a  112

a  114

b  111

b  122

b  134

c  125

so I want to change format using R.How to do that?

Solution

  • You could try:

     library(stringr)
 l1 <- lapply(str_extract_all(dat$value, "[0-9]+"), as.numeric)
 #library(stringi)
 #l1 <- lapply(stri_extract_all_regex(dat$value, "[0-9]+"), as.numeric)  #would be faster  
 data.frame(key=rep(dat$key,sapply(l1, length)), value=unlist(l1))
 #     key value
 #1   a   111
 #2   a   112
 #3   a   114
 #4   b   111
 #5   b   122
 #6   b   134
 #7   c   125

    Or

    library(data.table)
library(devtools)
source_gist(11380733)
cSplit(dat, "value", "[^0-9]", fixed=FALSE, direction="long")[value!="" ]
#   key value
#1:   a   111
#2:   a   112
#3:   a   114
#4:   b   111
#5:   b   122
#6:   b   134
#7:   c   125

    data

      dat <- structure(list(key = c("a", "b", "c"), value = c("[111,112,114]", 
 "[111,122,134]", "[125]")), .Names = c("key", "value"), class = "data.frame", row.names = c(NA, 
 -3L))