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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

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

Subject |
RE: st: Submitting a command in a couples of pieces |

Date |
Thu, 29 Oct 2009 23:39:36 +0100 |

<> Then restrain the options for the -_request()- thing to -local-s to avoid the confusion. Most of the time, users will want to process any input obtained via this -display- option immediately, so -local-s should be sufficient... HTH Martin -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Sergiy Radyakin Sent: Donnerstag, 29. Oktober 2009 23:36 To: statalist@hsphsun2.harvard.edu Subject: Re: st: Submitting a command in a couples of pieces -levelsof- requires a name of the local, _request requires a name of a local or a global. from the manual: "local(macname) insert the list of values in the local macro macname" it will not save into a global. It must be clear for Stata what the user means Best, S.R. On Thu, Oct 29, 2009 at 6:29 PM, Martin Weiss <martin.weiss1@gmx.de> wrote: > > <> > > " Martin, why is it unusual?" > > For the reasons I gave earlier. Stata`s internal handling is none of the > user`s business (apart from a few who drill to the very bottom of things, > not naming names...). The point is that Stata, to the best of my knowledge, > never demands that you prepend the underscore to the name of the -local- > yourself... See, for instance, -levelsof-. > > > HTH > Martin > > > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Sergiy Radyakin > Sent: Donnerstag, 29. Oktober 2009 22:00 > To: statalist@hsphsun2.harvard.edu > Subject: Re: st: Submitting a command in a couples of pieces > > On Thu, Oct 29, 2009 at 3:20 PM, Martin Weiss <martin.weiss1@gmx.de> wrote: >> >> <> >> >> "-_request()- will store the result in a local macro if you prefix its > name >> with an underscore" >> >> I spent most of the few minutes required for my reply wondering why I > could >> not get the -local- -macro- route to work. Now that Bill has pointed out > the >> solution, I appreciate that the last example, in [P] on p. 102, does say >> exactly what you are supposed to do to make this work. And yet: Is it not >> highly unusual that the user has to supply the underscore for the -local-? > > Martin, why is it unusual? > > manual for -display- says: > ... _request(macname) ... > we know that the names of local macros all start with an underscore > (check it with -macro dir- after defining some locals and globals) > so to tell Stata whether macname means local or global you put an > underscore. > > other commands may allow you to do the same. consider for example: > . mata st_global("_mylocal","my local value") > . display "`mylocal'" > my local value > > same applies to plugins. In fact plugins do not make a difference, see > the plugins manual: "By macros we mean both global macros and local > macros (local to the program calling the plugin). Internally, global > macros and local macros share the same namespace, with the names of > local macros preceded by an underscore (_). " > > I believe this is a rather historical thing. Already in the Stata 5 > manual ([R] macro, p.408) we read that:"The command local is formally > defined as equivalent to global _". > And this text survived unchanged to the Stata 11 manual ([P] macro, > p.194). So, if anything, it is the behaviour of the local command that > may be surprising: it does not require an underscore. > > Best regards, Sergiy Radyakin > > > >> (I cannot think of another command that requires this treatment). This > fact >> could be given more prominence in the manual entry, as normally Stata > would >> prepend the underscore for you, as is obvious from: >> >> >> *** >> ma drop _allv >> local a 1 >> ma di >> *** >> > > **************************************************************************** > ***** > In this example, suppose you have: > > local a "Local" > global a "Global" > > How do you list the value of the local macro a? > Yes: > > macro list _a > > (or macro dir _a -- not sure why this works as well, but I don't mind, > both are quite intuitive). > > > > >> >> HTH >> Martin >> >> >> -----Original Message----- >> From: owner-statalist@hsphsun2.harvard.edu >> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of William Gould, >> StataCorp LP >> Sent: Donnerstag, 29. Oktober 2009 20:03 >> To: statalist@hsphsun2.harvard.edu >> Subject: Re: st: Submitting a command in a couples of pieces >> >> Adrian Sayers <Adrian.Sayers@bristol.ac.uk> asks, >> >>> [...] i want stata to ask me a question, then i want to key the >>> response, and then i want stata to run a program. It sounds a little >>> pointless but i am trying read in 3000 odd data files plot them and then >>> trim the file to the relevant section. >>> >>> eg. >>> di "What is the first day of data collection?" >>> Type 3 >>> di "Day of first data collection = 3" >>> drop if day<3 >> >> Martin Weiss <martin.weiss1@gmx.de> replied, >> >>> ************* >>> di "What is the first day of data collection?" _request(day) >>> 3 >>> di "Day of first data collection =$day " >>> drop if day<$day >>> ************* >> >> Exactly right. Let me add a few details. >> >> -_request()- will store the result in a local macro if you prefix its name >> with an underscore, so Martin's answer could have read, >> >> di "What is the first day of data collection?" _request(_day) >> 3 >> di "Day of first data collection =`day' " >> drop if day<`day' >> >> Note that I put -_day- in the -_request()-, but even so, after that, I >> referred to -`day'- just as I usually would. >> >> Here's Martin's answer put into a -program-, which might be an ado-file: >> >> >> program trythis >> version 11 >> >> di "What is the day of the data collection? " _request(_day) >> di "Day of the first data collection = `day'" >> drop if day<`day' >> end >> >> >> I next suggest to Adrian that if he is going to ask more than one > question, >> he must anticipate that users will sometimes mistype their answers. >> Most commonly, they will hit Return before typing any answer. As I > result, >> I recommend creating a subroutine to get answers: >> >> >> program trythis >> version 11 >> >> askquestion "What is the day of the data collection?" >> local day "`s(answer)'" >> di "Day of the first data collection = `day'" >> drop if day<`day' >> end >> >> >> program askquestion, sclass >> args last_line_of_text >> while (1) { >> di as txt "`last_line_of_text' -> " _request(_answer) >> if ("`answer'"=="") { >> di as txt "Please answer question, or type" /// >> as res "qq" as txt "to break." >> } >> else if ("`answer'"=="qq") { >> exit 1 >> } >> else { >> sreturn local answer "`answer'" >> exit >> } >> } >> end >> >> In the above code, if the user just presses Return, the question is asked >> again. The user can type -qq- to have the code break (stop asking >> questions). >> >> If I were Adrian, I would also check the lexical class of the answer in >> subroutine -askquestion-. Sometimes answers can be text, even blank, >> and other times they must be numbers, and even integers. Adrian needs >> to think about the types of the answers he will need. As a simple > example, >> we might modify -askquestion- to allow the caller to specify one of the >> following lexical types: >> >> text (meaning a non-blank string) >> number (any number, and only a number) >> integer (any number that is an integer) >> >> I would then construct code that looks something like this, >> >> program askquestion, sclass >> args lex_class last_line_of_text >> >> while (1) { >> sreturn clear >> askqustion_ask "`last_line_of_text'" >> local answer "`s(answer)'" >> >> if ("`answer'"=="qq") { >> exit 1 >> } >> >> if ("`answer'"!="") { >> askquestion_check `lex_class' "`answer'" >> if (`"s(invalid)'"=="") { >> sreturn local answer "`answer'" >> exit >> } >> } >> else { >> di as txt "Please answer question, or type" /// >> as res "qq" as txt "to break." >> } >> } >> end >> >> program askquestion_ask, sclass >> args text >> di as txt "`text'" -> " _request(_answer) >> sreturn local answer "`answer'" >> end >> >> program askquestion_check, sclass >> args lex answer >> >> if ("`lex'"=="text") { >> exit >> } >> >> if ("`lex'"=="number") { >> capture confirm number `answer' >> if (_rc) { >> di "You must answer with a number" >> sreturn local invalid invalid >> } >> exit >> } >> >> if "`lex'"=="integer") { >> capture confirm number `answer' >> if (_rc) { >> di "You must answer with an integer" >> sreturn local invalid invalid >> } >> exit >> } >> >> di as error "Invalid lexical class -`lex'-" >> di as error "caller has error" >> exit 198 >> end >> >> >> All that said, there's nothing wrong with Martin's original answer if >> Adrian will only be asking a few questions and asking them of himself. >> >> -- Bill >> wgould@stata.com >> * >> * 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/ >> > > * > * 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/ > * * 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/

**References**:**Re: st: Submitting a command in a couples of pieces***From:*wgould@stata.com (William Gould, StataCorp LP)

**Re: st: Submitting a command in a couples of pieces***From:*Sergiy Radyakin <serjradyakin@gmail.com>

**Re: st: Submitting a command in a couples of pieces***From:*Sergiy Radyakin <serjradyakin@gmail.com>

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