Metapost label - Truncating digits after decimal point

Metapost label - Truncating digits after decimal point

[Curiouslearn]

Hi,

Is it possible to truncate the digits after decimal point in Metapost
when using textext()? Please see the minimal example below which
produces 1.84375. Can I just keep the first digit and have it produce
1.8 ?

Thanks.

\setuppapersize[letter][letter]

\setupcolors[state=start]


\starttext

\startuseMPgraphic{Figure}
	u := 1cm;
	pickup pencircle scaled 2pt; % default pen thickness
	%TheFunction
		vardef f(expr x) =
			(10/x)-x*((0.5)**x)
		enddef;
	%Labels	
		label.lft(textext(decimal f(5)),(0,f(5)) scaled u);		
\stopuseMPgraphic
\useMPgraphic{Figure}

\stoptext
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wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: Metapost label - Truncating digits after decimal point

[Taco Hoekwater]

Curiouslearn wrote:
> Hi,
> 
> Is it possible to truncate the digits after decimal point in Metapost
> when using textext()? Please see the minimal example below which
> produces 1.84375. Can I just keep the first digit and have it produce
> 1.8 ?

Here is a helper macro for you:

def trunc_digits(expr n, origs) =
   hide(
     string s, tmp;
     numeric ii, e;
     e := -1;
     for i=1 upto length(origs):
       ii := i;
       tmp := substring (i-1,i) of origs;
       if tmp = ".": if n=0: ii:=ii-1; exitif true; fi e:=0; fi
       if e>=0: e := e+1; exitif e>n;  fi
     endfor;
     s:=substring(0,ii) of origs; )
   s
enddef;


When run this macro with the result of decimal() as second argument,
it will create a new string as many fractional digits as you specify
in the first argument:

   label.lft(textext(trunc_digits(1,decimal f(5))),(0,f(5)) scaled u);	

Best wishes,
Taco
___________________________________________________________________________________
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
___________________________________________________________________________________

Re: Metapost label - Truncating digits after decimal point

[Curiouslearn]

Thanks so much, Taco. I will try out the code below. Good to know that
Metapost has functions such as substring.




On Sun, Nov 29, 2009 at 3:32 AM, Taco Hoekwater <taco@elvenkind.com> wrote:
> Curiouslearn wrote:
>>
>> Hi,
>>
>> Is it possible to truncate the digits after decimal point in Metapost
>> when using textext()? Please see the minimal example below which
>> produces 1.84375. Can I just keep the first digit and have it produce
>> 1.8 ?
>
> Here is a helper macro for you:
>
> def trunc_digits(expr n, origs) =
>  hide(
>    string s, tmp;
>    numeric ii, e;
>    e := -1;
>    for i=1 upto length(origs):
>      ii := i;
>      tmp := substring (i-1,i) of origs;
>      if tmp = ".": if n=0: ii:=ii-1; exitif true; fi e:=0; fi
>      if e>=0: e := e+1; exitif e>n;  fi
>    endfor;
>    s:=substring(0,ii) of origs; )
>  s
> enddef;
>
>
> When run this macro with the result of decimal() as second argument,
> it will create a new string as many fractional digits as you specify
> in the first argument:
>
>  label.lft(textext(trunc_digits(1,decimal f(5))),(0,f(5)) scaled u);
>
> Best wishes,
> Taco
> ___________________________________________________________________________________
> 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
___________________________________________________________________________________

Re: Metapost label - Truncating digits after decimal point

[Aditya Mahajan]

On Sat, 28 Nov 2009, Curiouslearn wrote:

> Hi,
>
> Is it possible to truncate the digits after decimal point in Metapost
> when using textext()? Please see the minimal example below which
> produces 1.84375. Can I just keep the first digit and have it produce
> 1.8 ?
>
> Thanks.

If you are using mkiv, you can use lua to truncate a number.

\unexpanded\def\truncate#1{\ctxlua{context("\%.1f", #1)}}

\startMPdefinitions
   def truncatedtext(expr s) =
     textext("\truncate{" & s & "}")
   enddef ;
\stopMPdefinitions

\starttext
\startuseMPgraphic{Figure}
   u := 1cm;
   pickup pencircle scaled 2pt; % default pen thickness
   %TheFunction
   vardef f(expr x) =
           (10/x)-x*((0.5)**x)
   enddef;
   %Labels
   %label.lft(textext("\truncate{" & decimal f(5) & "}"),(0,f(5)) scaled u);
   label.lft(truncatedtext(decimal f(5)),(0,f(5)) scaled u);
\stopuseMPgraphic
\useMPgraphic{Figure}


\stoptext

Aditya
___________________________________________________________________________________
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
___________________________________________________________________________________

Re: Metapost label - Truncating digits after decimal point

[Curiouslearn]

Thanks for this solution. Sounds small and clean. I need to learn Lua I guess.



On Tue, Dec 15, 2009 at 5:34 AM, Aditya Mahajan <adityam@umich.edu> wrote:
> On Sat, 28 Nov 2009, Curiouslearn wrote:
>
>> Hi,
>>
>> Is it possible to truncate the digits after decimal point in Metapost
>> when using textext()? Please see the minimal example below which
>> produces 1.84375. Can I just keep the first digit and have it produce
>> 1.8 ?
>>
>> Thanks.
>
> If you are using mkiv, you can use lua to truncate a number.
>
> \unexpanded\def\truncate#1{\ctxlua{context("\%.1f", #1)}}
>
> \startMPdefinitions
>  def truncatedtext(expr s) =
>    textext("\truncate{" & s & "}")
>  enddef ;
> \stopMPdefinitions
>
> \starttext
> \startuseMPgraphic{Figure}
>  u := 1cm;
>  pickup pencircle scaled 2pt; % default pen thickness
>  %TheFunction
>  vardef f(expr x) =
>          (10/x)-x*((0.5)**x)
>  enddef;
>  %Labels
>  %label.lft(textext("\truncate{" & decimal f(5) & "}"),(0,f(5)) scaled u);
>  label.lft(truncatedtext(decimal f(5)),(0,f(5)) scaled u);
> \stopuseMPgraphic
> \useMPgraphic{Figure}
>
>
> \stoptext
>
> Aditya
> ___________________________________________________________________________________
> 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
___________________________________________________________________________________