Does anyone have time to see if this post uses data.table correctly : http://stackoverflow.com/questions/4322219/whats-the-fastest-way-to-merge-join-data-frames-in-r
The dt[, colMeans(cbind(x, y)), by="g1,g2"] bit looks wrong to me. Is that why it takes 131 seconds vs 2.73 for sqldf ? Shouldn't it be dt[,list(mean(x),mean(y)),by="g1,g2"] ? And also the y2= bit of dt1[dt2,list(x,y1,y2=dt2$y2)] looks odd. Matthew _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
