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From |
vwiggins@stata.com (Vince Wiggins, StataCorp) |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Slower in v10 than v9 |

Date |
Mon, 03 Mar 2008 11:32:58 -0600 |

Nick Winter <nwinter@virginia.edu> writes that -graph combine- is slower under Stata 10 than it was under Stata 9. Nick is right. To elaborate a bit, it is the same speed when combining graphs that have been saved to disk, but it is slower when combining memory graphs. Graphs now combine the same speed whether they are memory graphs or graphs on disk. In Stata 8 and 9 we played a computer-science trick to increase speed -- we combined memory graphs by reference. The graphs were not recreated, the original graph was simply referenced from the combined graph. The sub-graph in the combined graph and the original memory graph were actually one-and-the-same graph. They might look different because they were drawn into a different space, but they were the same graph. When a graph on disk was combined it had to be created. In Stata 10 we have a graph editor. Had we continued to combine memory graphs by reference and you edited the original graph, the edits would have appeared in both the original AND the combined graph. The same would be true if you edited the sub-graph in the combined graph, the edits would have appeared on you original graph (the next time it was redrawn). That's kind of interesting, but not what you wanted. So, in Stata 10 memory graphs must be recreated when they are combined. If Nick wants his speed back he can add the undocumented option -nocopies- to his -graph combine- command. Memory graphs will then be combined by reference, as it was in Stata 9. Nick should be careful about editing the either the original or combined graph. -- Vince vwiggins@stata.com * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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