Creates an object of class DocumentTermMatrix from tm.

create_matrix creates a document-term matrix

create_matrix(
  textColumns,
  language = "english",
  minDocFreq = 1,
  minWordLength = 3,
  removeNumbers = TRUE,
  removePunctuation = TRUE,
  removeSparseTerms = 0,
  removeStopwords = TRUE,
  stemWords = FALSE,
  stripWhitespace = TRUE,
  toLower = TRUE,
  weighting = weightTf
)

Arguments

textColumns	Either character vector (e.g. data$Title) or a `cbind()` of columns to use for training the algorithms (e.g. `cbind(data$Title,data$Subject)`).
language	The language to be used for stemming the text data.
minDocFreq	The minimum number of times a word should appear in a document for it to be included in the matrix. See package tm for more details.
minWordLength	The minimum number of letters a word should contain to be included in the matrix. See package tm for more details.
removeNumbers	A `logical` parameter to specify whether to remove numbers.
removePunctuation	A `logical` parameter to specify whether to remove punctuation.
removeSparseTerms	See package tm for more details.
removeStopwords	A `logical` parameter to specify whether to remove stopwords using the language specified in language.
stemWords	A `logical` parameter to specify whether to stem words using the language specified in language.
stripWhitespace	A `logical` parameter to specify whether to strip whitespace.
toLower	A `logical` parameter to specify whether to make all text lowercase.
weighting	Either `weightTf` or `weightTfIdf`. See package tm for more details.

Author

Timothy P. Jurka <tpjurka@ucdavis.edu>

Examples

# DEFINE THE DOCUMENTS

documents <- c("I am very happy, excited, and optimistic.",
"I am very scared, annoyed, and irritated.",
"Iraq's political crisis entered its second week one step closer to the potential
dissolution of the government, with a call for elections by a vital coalition partner
and a suicide attack that extended the spate of violence that has followed the withdrawal
of U.S. troops.",
"With nightfall approaching, Los Angeles authorities are urging residents to keep their
outdoor lights on as police and fire officials try to catch the person or people responsible
for nearly 40 arson fires in the last three days.")
matrix <- create_matrix(documents, language="english", removeNumbers=TRUE,
                        stemWords=FALSE, weighting=weightTfIdf)
#> Warning: custom functions are ignored