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Re: st: RE: reinstate data after -contract- and -reshape-


From   Michael McCulloch <mm@pinestreetfoundation.org>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: reinstate data after -contract- and -reshape-
Date   Sat, 28 Nov 2009 12:58:59 -0800

Thanks!
I modified my example to confirm restoration of the original dataset, using -cf-:

*** begin
clear all
set seed 1
set obs 1000
gen id=_n
gen month=1 + int(12*uniform())
gen year=2008 + int(2*uniform())
gen subject_type=1 + int(3*uniform())
la def lab_subjects 1 "no reply" 2 "screened" 3 "sampled", modify
la val subject_type lab_subjects
g m=(year-1960)*12+month-1
format m %tmm_CY
la var m "Calendar month"
levelsof m, loc(vs)
foreach v of loc vs {
la def m `v' "`:di `:format m' `v''", modify
}
la val m m
by m, sort: gen freq = _N // sort by the variable of interest and get the frequencies
by m: gen cumfreq = _N if _n == 1	// get the cumulative frequencies
replace cumfreq = sum(cumfreq)
tabdisp m, cell(freq cumfreq)
preserve
save original, replace
contract m subject_type, z f(one)
reshape wide one, j(subject_type) i(m)
g noreply=max(0,one1)
g screened=max(0,one1)+max(0,one2)
g sampled=max(0,one1)+max(0,one2)+max(0,one3)
sc sampled screened noreply m, recast(bar) xla(576/599,angle(90)) name(s)
restore
cf _all using original  // returns nothing if datasets are identical
***




On Nov 28, 2009, at 12:39 PM, Martin Weiss wrote:


<>

Stata is very reliable, so yes, it works the way it is supposed to. A good source is of course http://www.stata.com/help.cgi?preserve and the manual
entry on -preserve-. You can also dump your data into a -tempfile-, of
course.

Stata 11 also has a -snapshot- feature
(http://www.stata.com/help.cgi?snapshot), although I have not explored this
myself yet :-)


HTH
Martin


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Michael McCulloch
Sent: Samstag, 28. November 2009 21:35
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: RE: reinstate data after -contract- and -reshape-

Thanks Martin, from the UCLA tutorial site
(http://www.ats.ucla.edu/stat/Stata/faq/stata2hlm_dofile.htm
), I gather that it's as simple as:

***
preserve
whatever you want to do here...
restore
***

Is that reliably the case?
Michael



On Nov 28, 2009, at 12:28 PM, Martin Weiss wrote:


<>
The "advanced syntax" of -reshape- let`s you undo the previous -
reshape- in
a straightforward manner, but -contract- can only be undone via -
expand-.
Have you had a look at -preserve- and -restore-, though?


HTH
Martin

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Michael
McCulloch
Sent: Samstag, 28. November 2009 21:21
To: Statalist Statalist
Subject: st: reinstate data after -contract- and -reshape-

Dear Statalist members,
With the help of Nick Cox and Martin Weiss, I've created the following
data simulation for a graph to track research subject accrual.
My question is how to reinstate the original dataset after the  -
contract- and -reshape- commands. I know it's possible to -reshape-,
but not sure how to "reverse" the options. I don't think it's possible
to "-uncontract'", so I'm thinking some version of -restore-??

My understanding of those two commands is:
	-contract- makes a summary dataset of frequencies and percentages
that will be reported in the graph, and
	-reshape- puts them in wide form so they can be -stacked-

****
* Austin Nichols suggests:
clear all
set seed 1
set obs 1000
gen id=_n
gen month=1 + int(12*uniform())
gen year=2008 + int(2*uniform())
gen subject_type=1 + int(3*uniform())
la def lab_subjects 1 "no reply" 2 "screened" 3 "sampled", modify
la val subject_type lab_subjects
g m=(year-1960)*12+month-1
format m %tmm_CY
la var m "Calendar month"
levelsof m, loc(vs)
foreach v of loc vs {
la def m `v' "`:di `:format m' `v''", modify
}
la val m m
by m, sort: gen freq = _N		// sort by the variable of interest
and get
the frequencies
by m: gen cumfreq = _N if _n == 1	// get the cumulative frequencies
replace cumfreq = sum(cumfreq)
tabdisp m, cell(freq cumfreq)
contract m subject_type, z f(one)
reshape wide one, j(subject_type) i(m)
g noreply=max(0,one1)
g screened=max(0,one1)+max(0,one2)
g sampled=max(0,one1)+max(0,one2)+max(0,one3)
sc sampled screened noreply m, recast(bar) xla(576/599,angle(90))
name(s)
****



Best wishes,

Michael McCulloch
Pine Street Foundation
124 Pine Street
San Anselmo, CA 94960-2674
tel:	415-407-1357
fax: 	206-338-2391


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Best wishes,

Michael McCulloch
Pine Street Foundation
124 Pine Street
San Anselmo, CA 94960-2674
tel:	415-407-1357
fax: 	206-338-2391

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/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/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


Best wishes,

Michael McCulloch
Pine Street Foundation
124 Pine Street
San Anselmo, CA 94960-2674
tel:	415-407-1357
fax: 	206-338-2391


*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



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