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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Construct an immutable data frame.</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for idata.frame {plyr}"><tr><td>idata.frame {plyr}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2>Construct an immutable data frame.</h2> <h3>Description</h3> <p>An immutable data frame works like an ordinary data frame, except that when you subset it, it returns a reference to the original data frame, not a a copy. This makes subsetting substantially faster and has a big impact when you are working with large datasets with many groups. </p> <h3>Usage</h3> <pre> idata.frame(df) </pre> <h3>Arguments</h3> <table summary="R argblock"> <tr valign="top"><td><code>df</code></td> <td> <p>a data frame</p> </td></tr> </table> <h3>Details</h3> <p>This method is still a little experimental, so please let me know if you run into any problems. </p> <h3>Value</h3> <p>an immutable data frame </p> <h3>Examples</h3> <pre> system.time(dlply(baseball, "id", nrow)) system.time(dlply(idata.frame(baseball), "id", nrow)) </pre> <hr /><div style="text-align: center;">[Package <em>plyr</em> version 1.8.7 <a href="00Index.html">Index</a>]</div> </body></html>