tm (version 0.2-3.7)

sFilter: Statement Filter

Description

Filter metadata by special statements.

Usage

sFilter(object, s, ...)

Arguments

object

a TextDocCol to be the filter applied to.

s

a statement of format "tag1 == 'expr1' & tag2 == 'expr2' & ...".

...

arguments passed over by calling functions.

Value

• A Boolean vector to represent the subset of the DMetaData (extended for shifted up variables) data frame as specified by the statement.

Details

The statement s models a simple query language. It consists of an expression as passed over to a data frame for subsetting. Tags in s represent metadata variables. Variables only available at document level are shifted up to the data frame if necessary. Note that the metadata tags for the slots Author, DateTimeStamp, Description, ID, Origin and Heading are author, datetimestamp, description, identifier, origin and heading, respectively, to avoid name conflicts.

Examples

## Load example dataset
data("crude")

## Statement Filter returning TRUE for document with ID 127 and heading DIAMOND ...
sFilter(crude, "identifier == '127' & heading == 'DIAMOND SHAMROCK (DIA) CUTS CRUDE PRICES'")