/*****************************************************************************************************************

SAS file name: Gamma_Curves.sas
File location: 
_________________________________________________________________________________________________________________

Purpose: Describe the Gamma distribution and draw Probability Density function and 
         Cumulative Density Function for different values of the parameters. 
Author: Peter Clemmensen
Creation 04/03/2017

This program supports the Gamma Distribution examples on SASnrd.com

*****************************************************************************************************************/

/* Create Gamma PDF data */
data Gamma_PDF;
      do x=0 to 300 by 1;
         pdf1=pdf('Gamma', x, 0.5, 60);
         pdf2=pdf('Gamma', x, 1, 60);
         pdf3=pdf('Gamma', x, 2, 60);
         pdf4=pdf('Gamma', x, 3, 60);
         output;
      end;
run;

/* Draw PDF plots */;
ods graphics on / outputfmt=png;
****ods pdf file='/home/mstear0/Eosinophil/Eosinophildist.pdf'  dpi=600;
ods pdf file='Gammadist.pdf'  dpi=600;
title "Gamma Densities";
title2 "For different values of scale and shape parameters";
proc sgplot data = Gamma_PDF noautolegend;
   series x=x y=pdf1 / lineattrs=(thickness=2) legendlabel="shape = 0.5 scale = 60";
   series x=x y=pdf2 / lineattrs=(thickness=2) legendlabel="shape = 1    scale = 60";
   series x=x y=pdf3 / lineattrs=(thickness=2) legendlabel="shape = 2    scale = 60";
   series x=x y=pdf4 / lineattrs=(thickness=2) legendlabel="shape = 3    scale = 60";
   keylegend / position=NE location=inside across=1 noborder valueattrs=(Size=12 Weight=Bold);
   yaxis min=0 max=0.02 label="PROBABILITY DENSITY FUNCTION" labelattrs=(size=14 weight=Bold);
   xaxis min=0 max=300 label='VALUE' labelattrs=(size=14 weight=Bold);
run;
title;

proc univariate data=Gamma_PDF;
 var pdf1;
 histogram pdf1 / gamma lognormal;
 run;
 
/* Create Gamma CDF data */
/*
data Gamma_PDF;
      do x=0 to 10 by 0.01;
         cdf1=cdf('Gamma', x, 1, 2);
         cdf2=cdf('Gamma', x, 9, .5);
         cdf3=cdf('Gamma', x, 2, 2);
         output;
      end;
run;

/* Draw PDF plots */
/*
title "Gamma Cummulative Density Functions";
title2 "For Different Values of (*ESC*){unicode lambda} and a";
proc sgplot data = Gamma_PDF noautolegend;
   series x=x y=cdf1 / lineattrs=(thickness=3) legendlabel="(*ESC*){unicode lambda} = 2 a = 1";
   series x=x y=cdf2 / lineattrs=(thickness=3) legendlabel="(*ESC*){unicode lambda} = 0.5 a = 9";
   series x=x y=cdf3 / lineattrs=(thickness=3) legendlabel="(*ESC*){unicode lambda} = 2 a = 2";
   keylegend / position=NW location=inside across=1 noborder valueattrs=(Size=12 Weight=Bold);
   yaxis min=0 max=1 label="CDF" labelattrs=(size=12 weight=Bold);
   xaxis min=0 max=10 label='x' labelattrs=(size=12 weight=Bold);
run;
title;
*/
/*
%let a=2;
%let lambda=2;
 
data PDF;
      do x=0 to 15 by 0.01;
         pdf=pdf('Gamma', x, &a, &lambda);
         output;
      end;
run;
 
 
title "Gamma Probability Densities.";
title2 "For Different Values of a=&a and (*ESC*){unicode lambda}=&lambda.";
proc sgplot data = PDF noautolegend;
   series x=x y=pdf/ lineattrs=(thickness=3) legendlabel="a = 1 (*ESC*){unicode lambda} = 3";
   yaxis label="PDF" labelattrs=(size=12 weight=Bold);
   xaxis label='x' labelattrs=(size=12 weight=Bold);
run;
title;
 */