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From |
Andrew Maurer <Andrew.Maurer@qrm.com> |

To |
"statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: -collapsetofile- |

Date |
Fri, 28 Feb 2014 18:51:22 +0000 |

Thanks for the reference, David. Looking at xcollapse.do, it internally does a preserve/save/restore. The whole idea of -collapsetofile- is to save the data without doing a preserve/restore. It looks like the intended purpose of -xcollapse- is to add features to collapse, while the purpose of -collapsetofile- is to save a file faster. (-collapsetofile-, at the moment, does far less then collapse - I still need to spend some time reading through the syntax-parsing portion of collapse to allow syntax like (sum) x1 = y x2 = z...) It looks like I need a RePEc account to post to SSC, if I'm understanding this. I'm looking into it now. Andrew Maurer -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox Sent: Friday, February 28, 2014 12:47 PM To: statalist@hsphsun2.harvard.edu Subject: Re: st: -collapsetofile- Using SSC as a medium for distributing user-written programs is naturally entirely optional for user-programmers. It is however I think germane that SSC requires provision of help files as part of a minimum standard for inclusion of packages. Similarly, providing help files would help people to understand exactly what these programs do and help Andrew get good feedback from anyone interested. (If I am missing the help files, please do flag where they are.) Nick njcoxstata@gmail.com On 28 February 2014 18:24, Jorge Eduardo Pérez Pérez <jorge_perez@brown.edu> wrote: > Thanks Andrew, this looks useful. > > Why not submit the code to SSC to make it easier for users to install > this directly from Stata? > > > -------------------------------------------- > Jorge Eduardo Pérez Pérez > Graduate Student > Department of Economics > Brown University > > > On Fri, Feb 28, 2014 at 1:19 PM, Nick Cox <njcoxstata@gmail.com> wrote: >> -save- is part of the executable >> >> . which save >> built-in command: save >> >> and so its code is not accessible to users. >> >> Nick >> njcoxstata@gmail.com >> >> >> On 28 February 2014 18:06, Andrew Maurer <Andrew.Maurer@qrm.com> wrote: >>> Hi Statalist, >>> >>> I've written a pair of program -collapsetofile- and -recover- to allow users to "collapse" data to a file without destroying the dataset like -collapse- does. I don't know if anyone else will have use for this, but it will save me a lot of computer time when dealing with large datasets. I would be very interested if anyone has any input or comments on how to improve coding efficiency / style (the code is still a bit rough). >>> >>> ado file (collapsetofile.ado): http://codepad.org/DcwtvDEb ado file >>> (recover.ado) : http://codepad.org/csZhQvb0 sthlp file >>> (collapsetofile.sthlp): http://codepad.org/AsKC79uK >>> >>> The biggest improvement would come from being able to save directly to a .dta. I assume that this would require either: >>> 1) looking at the format/header/footer of stata dtas in clear text >>> and fwrite()'ing it from mata, and/or >>> 2) looking at the source for a command like save and just copying >>> that (is the source for -save- available?) >>> >>> Before writing this I found myself waiting for hours when graphing summary statistics of large datasets with sequences of: >>> >>> use fulldata // this could be >10gb >>> preserve >>> collapse (sum) thisvar thatvar, by(byvar1 byvar2) ... some data >>> manipulation twoway line... >>> restore >>> >>> preserve >>> collapse (sum) anothervar yetanothervar, by(byvar3) ... some data >>> manipulation twoway line... >>> restore >>> >>> ... >>> >>> preserve >>> collapse (sum) more vars, by(byvar10) ... some data manipulation >>> twoway line... >>> restore >>> >>> For a 20gb dataset with 10 graphs, that makes 10 preserves/restores * 20gb = 200gb written/read to disk. -collapsetofile- writes just the collapsed data to be graphed to a file with no other disk reads/writes: >>> >>> use fulldata >>> collapsetofile (sum) thisvar thatvar using dataforgraph1, by(byvar1 >>> byvar2) collapsetofile (sum) anothervar yetanothervar dataforgraph2, >>> by(byvar3) ... >>> collapsetofile (sum) more vars, by(byvar10) >>> >>> recover dataforgraph1, clear >>> ... some data manipulation >>> twoway line... >>> ... >>> recover dataforgraph2, clear >>> ... some data manipulation >>> twoway line... >>> ... >>> >>> Thanks to Nick Cox for mentioning the importance of saving characteristics/metadata with the dataset. >>> Thanks to Sergiy Radyakin for making me realize that I could never write a mata program that would compute stats "by" variables as fast as stata's -_mean- in -collapse-, since stata's built-in C code can take advantage of parallelization, while mata code cannot. >> >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: -collapsetofile-***From:*Nick Cox <njcoxstata@gmail.com>

**References**:**st: -collapsetofile-***From:*Andrew Maurer <Andrew.Maurer@qrm.com>

**Re: st: -collapsetofile-***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: -collapsetofile-***From:*Jorge Eduardo Pérez Pérez <jorge_perez@brown.edu>

**Re: st: -collapsetofile-***From:*Nick Cox <njcoxstata@gmail.com>

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