RcppMeCab

This package, RcppMeCab, is a Rcpp wrapper for the part-of-speech morphological analyzer MeCab. It supports native utf-8 encoding in C++ code and CJK (Chinese, Japanese, and Korean) MeCab library. This package fully utilizes the power Rcpp brings R computation to analyze texts faster.

Installation

Linux and Mac OSX

First, install MeCab of your language-of-choice.

• Japanese: MeCab from github
• Korean: MeCab-Ko from Bitbucket repository
• Chinese: MeCab and MeCab Chinese Dic from MeCab-Chinese

Second, you can install RcppMeCab from CRAN with:

install.packages("RcppMeCab") # build from source
# install.packages("devtools")
install_github("junhewk/RcppMeCab") # install developmental version

Windows

You should set the language you want to use for the analysis with the environment variable MECAB_LANG. The default value is ko and if you want to analyze Japanese or Chinese, please set it as jp before install the package.

install.packages("RcppMeCab") # for installing Korean version

# or, install for Japanese
Sys.setenv(MECAB_LANG = 'ja') # for installing Japanese developmental version
install.packages("RcppMeCab", type="source") # build from source

# install.packages("devtools")
install_github("junhewk/RcppMeCab") # install developmental version

For analyzing, you also need MeCab binary and dictionary.

For Korean:

Install mecab-ko-msvc and mecab-ko-dic-msvc up to your 32-bit or 64-bit Windows version in C:\mecab. Provide directory location to RcppMeCab function.

For Japanese:

Install mecab binary. Provide directory location to RcppMeCab function. For example: pos(sentence, sys_dic = "C:/PROGRA~2/mecab/dic/ipadic")

Usage

This package has pos and posParallel function.

pos(sentence) # returns list, sentence will present on the names of the list
pos(sentence, join = FALSE) # for yielding morphemes only (tags will be given on the vector names)
pos(sentence, format = "data.frame") # the result will returned as a data frame format
pos(sentence, user_dic) # gets a compiled user dictionary 
posParallel(sentence, user_dic) # parallelized version uses more memory, but much faster than the loop in single threading

• sentence: a text for analyzing
• join: If it gets TRUE, output form is (morpheme/tag). If it gets FALSE, output form is (morpheme) + tag in attribute.
• format: The default is a list. If you set this as `“data.frame”, the function will return the result in a data frame format.
• sys_dic: a directory in which dicrc file is located, default value is "" or you can set your default value using options(mecabSysDic = "")
• user_dic: a user dictionary file compiled by mecab_dict_index, default value is also ""

Compiling User Dictionary

MeCab API has DictionaryCompiler, but it contains die(). Hence, calling it in Rcpp crashes down entire R session. This will not be included in RcppMeCab functions.

Please refer to Mecab for Japanese.

Unix and Mac OSX

You should have model_file if you want the library to estimate cost automatically.

• Japanese: model_file in ipadic
• Korean: model.bin in mecab-ko-dic

You need entire mecab-ko-dic source if you want to compile Korean user dictionary. User dictionary should also be prepared in CSV file. CSV structure is found in Japanese and Korean.

Compile:

$ /usr/local/libexec/mecab/mecab-dict-index -m `model_file` -d `mecab_dic_location` -u `user_dictionary_file_name` -f `CSV file charset` -t `original dictionary charset` `target_csv

# example

$ /usr/local/libexec/mecab/mecab-dict-index -m /usr/local/lib/mecab/dic/mecab-ko-dic/model.bin -d ~/mecab-ko-dic-2.0.3-20170922 -u userdic.dic -f utf8 -t utf8 ~/person.csv

Windows

• Korean: mecab-ko-msvc has mecab-dict-index.exe.
• Japanese: MeCab binary version has mecab-dict-index.exe.

You can use it in the same way the Linux binary compiles the dictionary.

TODOs

• Test multilanguage support
• Provide other useful functions
• Provide multilanguage manuals for international support

Author

Junhewk Kim (junhewk.kim@gmail.com)