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Last data update: 2014.03.03

R: Get the common root/stem of words

wordStem

R Documentation

Get the common root/stem of words

Description

This function computes the stems of each of the given words in the vector. This reduces a word to its base component, making it easier to compare words like win, winning, winner. See http://snowball.tartarus.org/ for more information about the concept and algorithms for stemming.

Usage

wordStem(words, language = character(), warnTested = FALSE)

Arguments

`words`	a character vector of words whose stems are to be computed.
`language`	the name of a recognized language for the package. This should either be a single string which is an element in the vector returned by `getStemLanguages`, or alternatively a character vector of length 3 giving the names of the routines for creating and closing a Snowball `SN_env` environment and performing the stem (in that order). See the example below.
`warnTested`	an option to control whether a warning is issued about languages which have not been explicitly tested as part of the unit testing of the code. For the most part, one can ignore these warnings and so they are turned off. In the future, we might consider controlling this with a global option, but for now we suppress the warnings by default.

Details

This uses Dr. Martin Porter's stemming algorithm and the interface generated by Snowball http://snowball.tartarus.org/.

Value

A character vector with as many elements as there are in the input vector with the corresponding elements being the stem of the word.

Author(s)

Duncan Temple Lang <duncan@wald.ucdavis.edu>

References

See http://snowball.tartarus.org/

Examples


   # Simple example
   # "win"    "win"    "winner"
 wordStem(c("win", "winning", 'winner'))


  # test the supplied vocabulary.
 testWords = readLines(system.file("words", "english", "voc.txt", package = "RTextTools"))
 validate = readLines(system.file("words", "english", "output.txt", package = "RTextTools"))

## Not run: 
 # Read the test words directly from the snowball site over the Web
 testWords = readLines(url("http://snowball.tartarus.org/english/voc.txt"))

## End(Not run)


 testOut = wordStem(testWords)
 all(validate == testOut)

  # Specify the language from one of the built-in languages.
 testOut = wordStem(testWords, "english")
 all(validate == testOut)

  # To illustrate using the dynamic lookup of symbols that allows one
  # to easily add new languages or create and close environment
  # routines (for example, to manage pools if this were an efficiency
  # issue!)
 testOut = wordStem(testWords, c("testDynCreate", "testDynClose", "testDynStem"))

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(RTextTools)
Loading required package: SparseM

Attaching package: 'SparseM'

The following object is masked from 'package:base':

    backsolve

> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/RTextTools/wordStem.Rd_%03d_medium.png", width=480, height=480)
> ### Name: wordStem
> ### Title: Get the common root/stem of words
> ### Aliases: wordStem
> ### Keywords: IO utilities
> 
> ### ** Examples
> 
> 
>    # Simple example
>    # "win"    "win"    "winner"
>  wordStem(c("win", "winning", 'winner'))
[1] "win"    "win"    "winner"
> 
> 
>   # test the supplied vocabulary.
>  testWords = readLines(system.file("words", "english", "voc.txt", package = "RTextTools"))
Warning message:
In file(con, "r") :
  file("") only supports open = "w+" and open = "w+b": using the former
>  validate = readLines(system.file("words", "english", "output.txt", package = "RTextTools"))
Warning message:
In file(con, "r") :
  file("") only supports open = "w+" and open = "w+b": using the former
> 
> ## Not run: 
> ##D  # Read the test words directly from the snowball site over the Web
> ##D  testWords = readLines(url("http://snowball.tartarus.org/english/voc.txt"))
> ## End(Not run)
> 
> 
>  testOut = wordStem(testWords)
>  all(validate == testOut)
[1] TRUE
> 
>   # Specify the language from one of the built-in languages.
>  testOut = wordStem(testWords, "english")
>  all(validate == testOut)
[1] TRUE
> 
>   # To illustrate using the dynamic lookup of symbols that allows one
>   # to easily add new languages or create and close environment
>   # routines (for example, to manage pools if this were an efficiency
>   # issue!)
>  testOut = wordStem(testWords, c("testDynCreate", "testDynClose", "testDynStem"))
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>