Re: A macro which gives a random name

[Otared Kavian <otared@gmail.com>]

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 <pragma@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.wolfgang@gmail.com> wrote:
>>> 
>>> 
>>>> Am 18.04.2015 um 18:55 schrieb Otared Kavian <otared@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
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>> 
>> ___________________________________________________________________________________
>> 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
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