triples: Bind Triples to a Textmatrix

Description

Allows to store, manage and retrieve SPO-triples (subject, predicate, object) bound to the document columns of a document term matrix.

Usage

getTriple( M, subject, predicate )
setTriple( M, subject, predicate, object )
delTriple( M, subject, predicate, object )
getSubjectId( M, subject )

Arguments

the document term matrix (see textmatrix).

subject

column number or column name (e.g., "doc3" or 3).

predicate

predicate of the triple sentence (e.g., "has\_category" or "has\_grade").

object

value of the triple sentence (e.g., "14" or 14).

Value

textmatrix

the document-term matrix (including row and column names).

Details

SPO-Triples are simple facts of the uniform structure (subject, predicate, object). A subject is typically a document in the given document-term matrix M, i.e. its document title (as in the column names) or its column position. A key-value pair (the predicate and the object) can be bound to this subject.

This can be used, for example, to store classification information about the documents of the text base used.

The triple data is stored in the environment of M constructed by textmatrix().

Whenever a matrix has to be used which has not been generated by this function, its class should be set to 'textmatrix' and an environment has to be added manually via:

class(mymatrix) = "textmatrix"

environment(mymatrix) = new.env()

Alternatively, as.matrix() can be used to convert a matrix to a textmatrix. To spare memory, the manual method might be of advantage.

In getTriple(), the arguments subject and predicate are optional.

Examples

Run this code

# NOT RUN {
    x = matrix(2,2,3) # we fake a document term matrix
    rownames(x) = c("dog","mouse") # fake term names
    colnames(x) = c("doc1","doc2","doc3") # fake doc titles
    class(x) = "textmatrix" # usually done by textmatrix()
    environment(x) = new.env() # usually done by textmatrix()
    
    setTriple(x, "doc1", "has_category", "15")
    setTriple(x, "doc2", "has_category", "7")
    setTriple(x, "doc1", "has_grade", "5")
    setTriple(x, "doc1", "has_category", "11")
    
    getTriple(x, "doc1")
    getTriple(x, "doc1")[[2]]
    getTriple(x, "doc1", "has_category") # -> [1] "15" "11"
    
    delTriple(x, "doc1", "has_category", "15")
    getTriple(x, "doc1", "has_category") # -> [1] "11"
    
# }