bibliometrix (version 1.8)

termExtraction: Term extraction tool from textual fields of a manuscript

Description

It extracts terms from a textual field (abstract, title, author's keywords, etc.) of a bibliographic data frame.

Usage

termExtraction(M, Field = "TI", stemming = FALSE, language = "english",
  remove.numbers = TRUE, remove.terms = NULL, keep.terms = NULL,
  synonyms = NULL, verbose = TRUE)

Arguments

M

is a data frame obtained by the converting function convert2df. It is a data matrix with cases corresponding to articles and variables to Field Tag in the original ISI or SCOPUS file.

Field

is a character object. It indicates the field tag of textual data :

"TI"		Manuscript title
"AB"		Manuscript abstract
"ID"		Manuscript keywords plus

The default is Field = "TI".

stemming

is logical. If TRUE the Porter Stemming algorithm is applied to all extracted terms. The default is stemming = FALSE.

language

is a character. It is the language of textual contents ("english", "german","italian","french","spanish"). The default is language="english".

remove.numbers

is logical. If TRUE all numbers are deleted from the documents before term extraction. The default is remove.numbers = TRUE.

remove.terms

is a character vector. It contains a list of additional terms to delete from the documents before term extraction. The default is remove.terms = NULL.

keep.terms

is a character vector. It contains a list of compound words "formed by two or more terms" to keep in their original form in the term extraction process. The default is keep.terms = NULL.

synonyms

is a character vector. Each element contains a list of synonyms, separeted by ";", that will be merged into a single term (the first word contained in the vector element). The default is synonyms = NULL.

verbose

is logical. If TRUE the function prints the most frequent terms extracted from documents. The default is verbose=TRUE.

Value

the bibliometric data frame with a new column containing terms about the field tag indicated in the argument Field.

See Also

convert2df to import and convert an ISI or SCOPUS Export file in a bibliographic data frame.

biblioAnalysis function for bibliometric analysis

Examples

# NOT RUN {
# Example 1: Term extraction from titles

data(scientometrics)

# vector of compound words
keep.terms <- c("co-citation analysis","bibliographic coupling")

# term extraction
scientometrics <- termExtraction(scientometrics, Field = "TI",
remove.numbers=TRUE, remove.terms=NULL, keep.terms=keep.terms, verbose=TRUE)

# terms extracted from the first 10 titles
scientometrics$TI_TM[1:10]


#Example 2: Term extraction from abstracts

data(scientometrics)

# vector of terms to remove
remove.terms=c("analysis","bibliographic")

# term extraction
scientometrics <- termExtraction(scientometrics, Field = "AB", stemming=TRUE,language="english",
 remove.numbers=TRUE, remove.terms=remove.terms, keep.terms=NULL, verbose=TRUE)

# terms extracted from the first abstract
scientometrics$AB_TM[1]

# Example 3: Term extraction from keywords with synonyms

data(scientometrics)

# vector of synonyms 
synonyms <- c("citation; citation analysis", "h-index; index; impact factor")

# term extraction
scientometrics <- termExtraction(scientometrics, Field = "ID",
synonyms=synonyms, verbose=TRUE)


# }