Re: st: -collapsetofile-

[Nick Cox <njcoxstata@gmail.com>]

To get stuff on SSC, you just need to email Kit Baum with the files.
But as he announced very recently he is away from base right now.

http://repec.org/bocode/s/sscsubmit.html gives full details.

Nick
njcoxstata@gmail.com


On 28 February 2014 18:51, Andrew Maurer <Andrew.Maurer@qrm.com> wrote:
> 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.

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