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 The weaver Package
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Tools and extensions for processing Sweave documents
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Authors: Seth Falcon and Robert Gentleman

Abstract
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The weaver package provides extensions to the Sweave utilities
included in R's utils package.  The focus of the extensions is on
caching computationally expensive (time consuming) code chunks in
Sweave documents.  The weaver package uses Luke Tierney's codetools
package and Dirk Eddelbuettel's digest package to provide a caching
mechanism that tracks dependencies among the R code expressions in the
document.  This allows weaver to decide when the results of a
computation can be retrieved from the cache and when they must be
recomputed.  In this paper we demonstrate the use of weaver and
discuss its implementation.