Temat: Choinka dla SASowców

Rick Wicklin chyba nudził się :)
A tak na serio, to dobry sposób nauki :)

proc iml;

/* Using SAS to construct a Christmas Tree from an iterated function system,

   and adding ornaments and a star.

   Rick Wicklin 12/14/2012

   To construct an iterated function system in SAS, see

   http://blogs.sas.com/content/iml/2012/12/12/iterated-function-systems-and-barnsleys-fern-in-sas/

*/

/* 1. Each row is a 2x2 linear transforamtion */

/* Christmas tree */

L = {0.03    0   0    0.1,

     0.85 0.00  0.00 0.85,

     0.8 0.00  0.00 0.8,

     0.2 -0.08  0.15 0.22,

    -0.2  0.08  0.15 0.22,

	 0.25 -0.1  0.12 0.25,

    -0.2  0.1  0.12 0.2};

/* ... and each row is a translation vector */

B = {0 0,

     0 1.5,

     0 1.5,

     0 0.85,

     0 0.85,

     0 0.3,

     0 0.4

	 };

prob = { 0.02 0.6 0.1 0.07 0.07 0.07 0.07};

/* For convenience, transpose the L and B matrices */

L = L`; B = B`;



/* 3. iterate the discrete stochastic map */

N = 1e5;          /* number of iterations */

x = j(2,N); k = j(N,1);

x[,1] = {0, 2};   /* initial point */

call randseed(1);

call randgen(k, "Table", prob);



do i = 2 to N;

   x[,i] = shape(L[,k[i]], 2)*x[,i-1] + B[,k[i]];

end;



/* 4. plot the iteration history */

y = x`;

create IFS from y[c={"x" "y"}]; append from y; close IFS;



/* just for fun, create ornaments and colors */

idx = ceil(N*ranuni(j(500,1)));

x1 = x[1,idx]`;

jdx = loc(abs(x1)>0.04);

idx = idx[jdx];

x1 = x[1,idx]`;

y1 = x[2,idx]` - 0.1;

group = ceil(5*ranuni(j(nrow(idx),1)));

create Ornaments var {x1 y1 group}; append; close Ornaments;

quit;



/* basic IFS Christmas Tree */

ods graphics / width=200px height=400px;

proc sgplot data=IFS;

title "SAS Christmas Tree";

scatter x=x y=y / markerattrs=(size=1 color=ForestGreen);

yaxis display=none;

xaxis display=none;

run;



/* Add ornaments and star */

data Star;

x2=0; y2=10; output;

run;



data All;

merge IFS Ornaments Star;

if group=. then group=1;

run;



data Attrs;

length Value MarkerColor $20;

ID = "Ornaments"; 

Value = 1; MarkerColor = "Red    "; output;

Value = 2; MarkerColor = "Blue   "; output;

Value = 3; MarkerColor = "Purple "; output;

Value = 4; MarkerColor = "Gold   "; output;

Value = 5; MarkerColor = "Chartreuse"; output;

run;



*ods graphics / width=400px height=800px;

proc sgplot data=All noautolegend dattrmap=Attrs;

title "SAS Christmas Tree";

scatter x=x y=y / markerattrs=(size=1 color=ForestGreen);

scatter x=x1 y=y1 / transparency=0.33 attrid=Ornaments

        markerattrs=(size=8 symbol=CircleFilled) group=group;

scatter x=x2 y=y2 / markerattrs=(color=Gold size=15 symbol=StarFilled);

yaxis display=none;

xaxis display=none;

run;

źrodło: http://blogs.sas.com/content/iml/2012/12/14/a-fractal-...