Hi Hans, Many thanks for your wonderful code… I modified a little bit the names you use in your code so that it may be used for other purposes as well (for instance if one wishes to select at random a certain number of exercises from different subsets among a huge a dataset of problems). Again, for other people's possible needs, I put the modified code below (I don’t know in what category one might put your solution on the Wiki).
If I may ask three questions in order to understand better your code, I would like to know 1) Why is it necessary to have this line (please see below) local ListOfNames = { "G" , "W » } in the luacode. Is it only a sort of intitialisation? 2) You use a built-in function utilities.parsers.settings_to_array(list) is it a ConTeXt function defined somewhere in the core, or a Lua function? 3) Assuming one has a list of names in a file names (say in a comma separated format) in a file named my-list.tex how is it possible to use it in \SetListOfFunctionNames? Using \SetListOfFunctionNames[\input named my-list.tex] results in an error since \directlua does not accept \input. Best regards: OK %%%% begin choose-random-names.tex by Hans \startluacode local ListOfNames = { "G" , "W" } local ChosenName = ListOfNames[1] function document.SetListOfNames(list) ListOfNames = utilities.parsers.settings_to_array(list) end function document.GetChosenName(new) if new then ChosenName = ListOfNames[math.random(1,#ListOfNames)] end context(ChosenName) end \stopluacode \def\SetListOfFunctionNames[#1]{\ctxlua{document.SetListOfNames("#1")}} \def\NewFunctionName {\ctxlua{document.GetChosenName(true)}} \def\FunctionName {\ctxlua{document.GetChosenName()}} \SetListOfFunctionNames[a,b,c,d] \dorecurse{10}{ Give an example of a function $\NewFunctionName : {\Bbb R} \longrightarrow {\Bbb R}$ which has a derivative only at the origin, and such that $\FunctionName(0) = 1$. \par \hairline\par } \stoptext %%%% end choose-random-names.tex by Hans > On 18 Apr 2015, at 22:36, Hans Hagen <pra...@wxs.nl> wrote: > > On 4/18/2015 10:24 PM, Otared Kavian wrote: >> Hi again Wolfgang, >> >> Thanks to your hint, I could solve the problem… >> In case someone else would encounter a similar problem to solve, below is a >> macro which chooses an element from a list, it creates a control sequence >> (CS) containing that element and it keeps the CS until the next time the >> macro is invoked again to choose another element. >> >> Thanks again and best regards: OK >> >> %%%% begin choose-element.tex >> \setuprandomize[1989] % set a seed >> >> \starttext >> >> % here is a list from which a name is chosen >> \startluacode >> ListOfNames = {'F', 'G', 'u', 'v', 'W'} >> \stopluacode >> >> % this macro has two arguments: >> % the first argument is the control sequence name attached to Chosen, >> % the second argument is the name of the list from which something is chosen >> \define[2]\RandomChoice{% >> \setevalue{Chosen#1}{\ctxlua{% >> local listsize = \letterhash #2 ; >> local LName = #2 ; >> tex.print(LName[math.random(1,listsize)])}}} >> >> \dorecurse{10}{\RandomChoice{Function}{ListOfNames}% >> Give an example of a function $\ChosenFunction : {\Bbb R} \longrightarrow >> {\Bbb R}$ which has a derivative only at the origin, and such that >> ${\ChosenFunction}'(0) = 1$.\par \hairline\par} >> >> \stoptext >> %%%% end choose-element.tex > > \starttext > > \startluacode > local FunctionNames = { "G" , "W" } > local FunctionName = FunctionNames[1] > > function document.SetFunctionNames(list) > FunctionNames = utilities.parsers.settings_to_array(list) > end > function document.GetFunctionName(new) > if new then > FunctionName = FunctionNames[math.random(1,#FunctionNames)] > end > context(FunctionName) > end > \stopluacode > > \def\SetFunctionNames[#1]{\ctxlua{document.SetFunctionNames("#1")}} > \def\NewFunctionName {\ctxlua{document.GetFunctionName(true)}} > \def\GetFunctionName {\ctxlua{document.GetFunctionName()}} > > \SetFunctionNames[a,b,c,d] > > \dorecurse{10}{ > Give an example of a function > $\NewFunctionName : {\Bbb R} \longrightarrow {\Bbb R}$ > which has a derivative only at the origin, and such that > $\GetFunctionName(0) = 1$. > \par \hairline\par > } > > > \stoptext > > > >>> On 18 Apr 2015, at 19:23, Wolfgang Schuster <schuster.wolfg...@gmail.com> >>> wrote: >>> >>> >>>> Am 18.04.2015 um 18:55 schrieb Otared Kavian <ota...@gmail.com>: >>>> >>>> Hi everyone, >>>> >>>> In the example below I define a macro which chooses at random a name from >>>> a list of names. But I wonder whether this can be done in a more clever >>>> way without using a numerical macro created with math.random in Lua. The >>>> shortcoming of the macro below is that before hand I must know the nomber >>>> of elements in the list of names (for instance 5 in the example below), >>>> while it may happen that I need to create as many as random names that >>>> there are elements in the list, but sometimes I don’t know what is this >>>> number. >>>> >>>> Thanks for any insight and help. >>>> Best regards: OK >>>> %%%% begin random-names.tex >>>> \setuprandomize[2015] % set a seed >>>> >>>> \starttext >>>> >>>> \startluacode >>>> Name = {'F', 'G', 'u', 'v', 'W'} >>>> \stopluacode >>>> >>>> \define[3]\RandomName{% >>>> \setevalue{Named#1}{\ctxlua{tex.print(math.random(#2,#3))}}} >>>> \define\RandomFunctionName{\ctxlua{tex.print(Name[\NamedFunctionNumber])}} >>>> >>>> \dorecurse{10}{\RandomName{FunctionNumber}{1}{5}% >>>> Give an example of a function $\RandomFunctionName : {\Bbb R} >>>> \longrightarrow {\Bbb R}$ which has a derivative only at the origin, and >>>> such that $\RandomFunctionName(0) = 1$.\par \hairline\par} >>>> >>>> \stoptext >>>> %%%% begin random-names.tex >>> >>> You can access the size of your Name table with #Name but have to replace # >>> with \letterhash when you use it in a TeX command because # is already >>> taken for the TeX arguments. >>> >>> \starttext >>> >>> \startluacode >>> Name = {'F', 'G', 'u', 'v', 'W'} >>> \stopluacode >>> >>> \define\RandomFunctionName >>> {\startlua >>> local listsize = \letterhash Name ; >>> local randomvalue = math.random(1,listsize) ; >>> context(Name[randomvalue]) >>> \stoplua} >>> >>> \dorecurse{10}{Give an example of a function $\RandomFunctionName : {\Bbb >>> R} \longrightarrow {\Bbb R}$ which has a derivative only at the origin, and >>> such that $\RandomFunctionName(0) = 1$.\par \hairline\par} >>> >>> \stoptext >>> >>> Wolfgang >>> >>> ___________________________________________________________________________________ >>> If your question is of interest to others as well, please add an entry to >>> the Wiki! >>> >>> maillist : ntg-context@ntg.nl / >>> http://www.ntg.nl/mailman/listinfo/ntg-context >>> webpage : http://www.pragma-ade.nl / http://tex.aanhet.net >>> archive : http://foundry.supelec.fr/projects/contextrev/ >>> wiki : http://contextgarden.net >>> ___________________________________________________________________________________ >> >> ___________________________________________________________________________________ >> If your question is of interest to others as well, please add an entry to >> the Wiki! >> >> maillist : ntg-context@ntg.nl / >> http://www.ntg.nl/mailman/listinfo/ntg-context >> webpage : http://www.pragma-ade.nl / http://tex.aanhet.net >> archive : http://foundry.supelec.fr/projects/contextrev/ >> wiki : http://contextgarden.net >> ___________________________________________________________________________________ >> > > > -- > > ----------------------------------------------------------------- > Hans Hagen | PRAGMA ADE > Ridderstraat 27 | 8061 GH Hasselt | The Netherlands > tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com > | www.pragma-pod.nl > ----------------------------------------------------------------- > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://tex.aanhet.net > archive : http://foundry.supelec.fr/projects/contextrev/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________