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| From | Abhimanyu Arora <abhimanyu.arora1987@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: RE: local variables and running do files |
| Date | Sat, 29 Oct 2011 14:56:16 +0200 |
Thanks very much, Nick, for the illuminating post. These nuggets from experience indeed help in deepening our understanding. Best regards Abhimanyu On Sat, Oct 29, 2011 at 2:36 PM, Nick Cox <njcoxstata@gmail.com> wrote: > This is correct, and was pointed out earlier in the thread by Jorge > Eduardo Pérez Pérez and underlined by Matthew White. > > Indeed, you could use globals. > > The main objection to globals is I think one of style: it is just > generally considered good style that all definitions in computing, > like those in espionage or security, are on a need-to-know basis. > > Note that a global can have unpredictable side-effects elsewhere. This > is naturally the consequence of it being visible everywhere. So, > suppose you define a global; in principle you could be changing > something used by a program you use without knowing it. The risk is in > practice very small, but not zero. > > Stata users getting to grips with locals are often surprised by this > lack of visibility of local macros, even within the same session, but > two comments may provide some illumination. > > First, the name "local" is not an arbitrary jargon term, but conveys a > key hint about what locals are. > > Second, if locals really were visible elsewhere you would have to > worry about clashes between your locals and any locals defined in > Stata programs defining commands (lots and lots of them); those in the > programs they call, and that they call, and so on (lots and lots > more); and those in the user-written commands you use (similar story). > But this is not the case; otherwise the use of locals would be a > minefield even for experienced users, let alone for beginners. > > Nick > > On Sat, Oct 29, 2011 at 1:15 PM, Abhimanyu Arora > <abhimanyu.arora1987@gmail.com> wrote: > >> I guess Ana could make use of global macros for her problem (even as >> if I recall there was an advice in statalist preferring `locals', but >> I do not clearly recall the exact reason) >> Cheers >> Abhimanyu >> >> On Sat, Oct 29, 2011 at 3:12 AM, Nick Cox <njcoxstata@gmail.com> wrote: >>> It's the same question. The use of a local requires its prior >>> definition in the same locale. >>> "Locale", although a term used elsewhere in computing, is in this >>> context my term earlier defined in the thread. >>> >>> Nick >>> >>> On Fri, Oct 28, 2011 at 7:40 PM, Maria Ana Vitorino >>> <vitorino@wharton.upenn.edu> wrote: >>>> I am using Stata 11. >>>> But in any case what if I want to run some regressions, for example: >>>> >>>> reg y x1 x2 x3 >>>> >>>> is equiv to >>>> >>>> --regtest.do >>>> local x "x1 x2 x3" >>>> reg y `x' >>>> ---- >>>> >>>> >>>> but if after running the first 2 lines I want to run the command " sum `x' " >>>> it does not work. Is there anyway around this so that I don't have to >>>> define the local macro again? >>>> >>>> Thanks, >>>> Ana >>>> >>>> >>>> >>>> On Oct 28, 2011, at 2:30 PM, Nick Cox wrote: >>>> >>>>> The term "local variable" is to be avoided, as explained at >>>>> >>>>> http://www.stata.com/statalist/archive/2008-08/msg01258.html >>>>> >>>>> What you are seeing is a defining feature of a local macro: it is visible >>>>> only locally, i.e. within the locale in which it is defined, i.e. not >>>>> visible outside the interactive session, program, do file or do file editor >>>>> contents within which it is defined. >>>>> >>>>> You need to pass the contents of your local macro to the do-file as an >>>>> argument. If you write e.g. >>>>> >>>>> ------------ mydo.do >>>>> su `1' >>>>> ------------ >>>>> >>>>> And then go >>>>> >>>>> mydo "var1 var2" >>>>> >>>>> then the do file uses the argument you feed to it. Arguments are separated >>>>> by spaces and bound by " ". This is all explained in the chapter(s) on >>>>> do-files in [U], which is part of your Stata, as without declaring otherwise >>>>> it is assumed that you are using Stata 12. >>>>> >>>>> Nick >>>>> n.j.cox@durham.ac.uk >>>>> >>>>> Maria Ana Vitorino >>>>> >>>>> I would like to run a do file in batches (i.e. a few lines at a time) >>>>> but it seems that then the local variables that I defined in the >>>>> beginning do not carry over ... >>>>> Any solution for this? >>>>> >>>>> Here is some output for a simple example so that you can better >>>>> understand what is my issue. >>>>> >>>>> Thanks!! >>>>> Ana >>>>> >>>>> >>>>> . do "/var/folders/Xn/Xnl4Mq-lGR4-mNII1zm-Wk+++TI/-Tmp-//SD17268.000000" >>>>> >>>>> . sum >>>>> >>>>> Variable | Obs Mean Std. Dev. Min Max >>>>> -------------+-------------------------------------------------------- >>>>> var1 | 24 12.5 7.071068 1 24 >>>>> var2 | 24 36.5 7.071068 25 48 >>>>> var3 | 24 61.5 7.071068 50 73 >>>>> >>>>> . local var "var1 var2" >>>>> >>>>> . >>>>> end of do-file >>>>> >>>>> . do "/var/folders/Xn/Xnl4Mq-lGR4-mNII1zm-Wk+++TI/-Tmp-//SD17268.000000" >>>>> >>>>> . sum `var' >>>>> >>>>> Variable | Obs Mean Std. Dev. Min Max >>>>> -------------+-------------------------------------------------------- >>>>> var1 | 24 12.5 7.071068 1 24 >>>>> var2 | 24 36.5 7.071068 25 48 >>>>> var3 | 24 61.5 7.071068 50 73 >>>>> > > * > * 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/