[NTG-context] A macro which gives a random name

Otared Kavian otared at gmail.com
Sat Apr 18 22:24:02 CEST 2015


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

> On 18 Apr 2015, at 19:23, Wolfgang Schuster <schuster.wolfgang at gmail.com> wrote:
> 
> 
>> Am 18.04.2015 um 18:55 schrieb Otared Kavian <otared at 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
> 
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