mp: choose colors randomly from list

mp: choose colors randomly from list

[Schmitz Thomas A.]

Hi all,

I would like to have mp choose a (transparent) color randomly from a predefined list. My naive approach was (let’s restrict it to three colors):

\startuniqueMPgraphic{colortest}
save mycolor ; color mycolor[] ;
mycolor[1] := (0.07, 0.21, 0.65) ;
mycolor[2] := (0.6, 0.6, 0.4) ;
mycolor[3] := (0.5, 0.8, 0.5) ;
path p ;
p := unitsquare scaled 2cm ;
for i=1 upto 3:
fill p shifted (i*2.5cm, 0) withcolor transparent (1,0.3,mycolor[round(uniformdeviate(i))]) ;
endfor ;
\stopuniqueMPgraphic

\starttext

\uniqueMPgraphic{colortest}

\stoptext

Is there a better approach? The selection isn’t random enough for my taste :-) Sometimes, in my real document, I get black color, even though black isn’t in the list, so I suspect that mp doesn’t get a correct value for mycolor[round(uniformdeviate(i))]. And finally: how could I define the colors in a way that I could also use them outside of mp? Or do I have to copy-paste the definitions into \definecolor’s? 

All best

Thomas
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Re: mp: choose colors randomly from list

[Alan BRASLAU]

mycolor[1 + round (uniformdeviate 2)]

(or define mycolor[0]-mycolor[2], in which case you can drop the "1 +")

uniformdeviate returns a random number between zero and the value of
the argument. So you do not want (uniformdeviate i).

Alan

On Wed, 19 Feb 2014 11:10:57 +0100
Schmitz Thomas A. <thomas.schmitz@uni-bonn.de> wrote:

> Hi all,
> 
> I would like to have mp choose a (transparent) color randomly from a
> predefined list. My naive approach was (let’s restrict it to three
> colors):
> 
> \startuniqueMPgraphic{colortest}
> save mycolor ; color mycolor[] ;
> mycolor[1] := (0.07, 0.21, 0.65) ;
> mycolor[2] := (0.6, 0.6, 0.4) ;
> mycolor[3] := (0.5, 0.8, 0.5) ;
> path p ;
> p := unitsquare scaled 2cm ;
> for i=1 upto 3:
> fill p shifted (i*2.5cm, 0) withcolor transparent
> (1,0.3,mycolor[round(uniformdeviate(i))]) ; endfor ;
> \stopuniqueMPgraphic
> 
> \starttext
> 
> \uniqueMPgraphic{colortest}
> 
> \stoptext
> 
> Is there a better approach? The selection isn’t random enough for my
> taste :-) Sometimes, in my real document, I get black color, even
> though black isn’t in the list, so I suspect that mp doesn’t get a
> correct value for mycolor[round(uniformdeviate(i))]. And finally: how
> could I define the colors in a way that I could also use them outside
> of mp? Or do I have to copy-paste the definitions into
> \definecolor’s? 
> 
> All best
> 
> Thomas

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Re: mp: choose colors randomly from list

[Otared Kavian]

Hi Thomas,

One way is to increase the « degree of randomness » by saying
	withcolor transparent (1,0.3,mycolor[round(uniformdeviate(10*i)/10)])
or you can define a RandomColor as below:

\startuniqueMPgraphic{colortest}
save mycolor ; color mycolor[] ;
mycolor[1] := (0.07, 0.21, 0.65) ;
mycolor[2] := (0.6, 0.6, 0.4) ;
mycolor[3] := (0.5, 0.8, 0.5) ;
path p ;
p := unitsquare scaled 2cm ;
for i=1 upto 3:
fill p shifted (i*2.5cm, 0) withcolor transparent (1,0.3,mycolor[round(uniformdeviate(10*i)/10)]) ;
endfor ;
\stopuniqueMPgraphic

\ctxlua{
CoeffRed = math.random(1,100)/100 ; 
CoeffGreen = math.random(1,100)/100 ;
CoeffBlue = math.random(1,100)/100 ;
}
\def\CoeffRed{\ctxlua{tex.print(CoeffRed)}}
\def\CoeffGreen{\ctxlua{tex.print(CoeffGreen)}}
\def\CoeffBlue{\ctxlua{tex.print(CoeffBlue)}}

\definecolor[RandomColor]
	[r=\CoeffRed,
	g=\CoeffGreen,
	b=\CoeffBlue
	]

\starttext

\uniqueMPgraphic{colortest}

\startcolor[RandomColor]\bf This is a RandomColor \stopcolor

\stoptext

Best regards: OK

On 19 févr. 2014, at 11:10, Schmitz Thomas A. <thomas.schmitz@uni-bonn.de> wrote:

> Hi all,
> 
> I would like to have mp choose a (transparent) color randomly from a predefined list. My naive approach was (let’s restrict it to three colors):
> 
> \startuniqueMPgraphic{colortest}
> save mycolor ; color mycolor[] ;
> mycolor[1] := (0.07, 0.21, 0.65) ;
> mycolor[2] := (0.6, 0.6, 0.4) ;
> mycolor[3] := (0.5, 0.8, 0.5) ;
> path p ;
> p := unitsquare scaled 2cm ;
> for i=1 upto 3:
> fill p shifted (i*2.5cm, 0) withcolor transparent (1,0.3,mycolor[round(uniformdeviate(i))]) ;
> endfor ;
> \stopuniqueMPgraphic
> 
> \starttext
> 
> \uniqueMPgraphic{colortest}
> 
> \stoptext
> 
> Is there a better approach? The selection isn’t random enough for my taste :-) Sometimes, in my real document, I get black color, even though black isn’t in the list, so I suspect that mp doesn’t get a correct value for mycolor[round(uniformdeviate(i))]. And finally: how could I define the colors in a way that I could also use them outside of mp? Or do I have to copy-paste the definitions into \definecolor’s? 
> 
> All best
> 
> Thomas
> ___________________________________________________________________________________
> 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/
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___________________________________________________________________________________

Re: mp: choose colors randomly from list

[Schmitz Thomas A.]

On 19 Feb 2014, at 11:37, Alan BRASLAU <alan.braslau@cea.fr> wrote:

> uniformdeviate returns a random number between zero and the value of
> the argument. So you do not want (uniformdeviate i).

Ah, that explains it. Thanks a lot Alan!

Otared Kavian wrote:

> One way is to increase the « degree of randomness » by saying
> 	withcolor transparent (1,0.3,mycolor[round(uniformdeviate(10*i)/10)])
> or you can define a RandomColor as below:

I hate myself for not knowing more about math! I don’t see how mp picks its random numbers - when I recompile, I always get the same colors in the same order. They are “random” in the sense that there is no fixed order, but I was surprised that every run produces the same random order. RandomColor is nice, but not for my current purpose because I want to choose from a fixed list (colors are used as backgrounds, so I can only use dark colours, e.g.).

Thanks a lot!

Thomas
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___________________________________________________________________________________

Re: mp: choose colors randomly from list

[Wolfgang Schuster]

Am 19.02.2014 um 12:11 schrieb Schmitz Thomas A. <thomas.schmitz@uni-bonn.de>:

> I hate myself for not knowing more about math! I don’t see how mp picks its random numbers - when I recompile, I always get the same colors in the same order. They are “random” in the sense that there is no fixed order, but I was surprised that every run produces the same random order. RandomColor is nice, but not for my current purpose because I want to choose from a fixed list (colors are used as backgrounds, so I can only use dark colours, e.g.).

http://www.ntg.nl/pipermail/ntg-context/2012/065815.html

Wolfgang
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Re: mp: choose colors randomly from list

[Schmitz Thomas A.]

On 19 Feb 2014, at 12:16, Wolfgang Schuster <schuster.wolfgang@gmail.com> wrote:

> http://www.ntg.nl/pipermail/ntg-context/2012/065815.html
> 
> Wolfgang

Not only I’m bad at math, I don’t even remember the answers to my own questions - thanks Wolfgang for reminding me! I’m getting old and senile, should look into early retirement...

Thomas
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Re: mp: choose colors randomly from list

[Alan BRASLAU]

On Wed, 19 Feb 2014 12:38:38 +0100
Schmitz Thomas A. <thomas.schmitz@uni-bonn.de> wrote:

> Not only I’m bad at math, I don’t even remember the answers to my own
> questions - thanks Wolfgang for reminding me! I’m getting old and
> senile, should look into early retirement...

The random numbers generated are deterministic, that is each run will
reproduce the same "random" sequence. If you are looking for more
randomness, then you need to set "randomseed := numeric expression ;"
using something that varies in a less predictable manner. For example,
you can set
  randomseed := minute ;
where minute is the number of minutes past the hour of when the job was
started. So unless you have the habit of always processing your file at
the same minute of the hour, then your colors will vary.


Of course, if you want a truly random variable, then you need to use
some other physical process, like detecting the moment of passage of
cosmic radiation.

One point of view is that chance is simply a reflection of our limited
knowledge, our "bounded rationality". The classical expression of this
is due to Laplace:
\startquotation
All events, even those that, because of their insignificance, seem
not to be governed by the great laws of nature, are a consequence as
necessary as the revolution of the Sun. Through our ignorance of their
relationship to the system of the universe as a whole, we have them
depend on some cause or on chance, according to whether they appear to
occur with some regularity or not; But these imaginary causes have
successively diminished with the advance of the limits of our
knowledge, and disappear entirely before a sound philosophical analysis
who sees in them but an expression of our ignorance, for which we
ourselves are the real cause.
\stopquotation

Quantum mechanics has revised this point of view. However, you are the
classicist, and according to Aristote an accident (συμβεβηκός) or
chance (τὺχη αὐτόματον) or (σύμπτωμα) is just an encounter of two
independent casual series. (And here I am exposing MY ignorance of
Greek!) :)

Alan
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