update for exponential distribution object

INDEX

@@ -68,6 +68,7 @@ Descriptive Statistics
  trimmean
  var
 Distribution Classes
+ ExponentialDistribution
  GammaDistribution
  GeneralizedExtremeValueDistribution
  GeneralizedParetoDistribution

inst/dist_wrap/fitdist.m

@@ -188,11 +188,16 @@
       endif
 
     case "exponential"
-      warning ("fitdist: 'Exponential' distribution not supported yet.");
       if (isempty (groupvar))
-        varargout{1} = [];
+        varargout{1} = ExponentialDistribution.fit (x, alpha, censor, freq);
       else
-        varargout{1} = [];
+        pd = ExponentialDistribution.fit ...
+             (x(g==1), alpha, censor(g==1), freq(g==1));
+        for i = 2:groups
+          pd(i) = ExponentialDistribution.fit ...
+                  (x(g==i), alpha, censor(g==i), freq(g==i));
+        endfor
+        varargout{1} = pd;
         varargout{2} = gn;
         varargout{3} = gl;
       endif
@@ -230,7 +235,8 @@
 
     case {"generalizedpareto", "gp"}
       if (any (x - theta < 0))
-        error ("fitdist: invalid THETA value for generalized Pareto distribution.");
+        error (strcat (["fitdist: invalid THETA value for generalized"], ...
+                       [" Pareto distribution."]));
       endif
       if (isempty (groupvar))
         varargout{1} = GeneralizedParetoDistribution.fit ...
@@ -473,6 +479,22 @@
 
 ## Test output
 %!test
+%! x = exprnd (1, 100, 1);
+%! pd = fitdist (x, "exponential");
+%! [muhat, muci] = expfit (x);
+%! assert ([pd.mu], muhat);
+%! assert (paramci (pd), muci);
+%!test
+%! x1 = exprnd (1, 100, 1);
+%! x2 = exprnd (5, 100, 1);
+%! pd = fitdist ([x1; x2], "exponential", "By", [ones(100,1); 2*ones(100,1)]);
+%! [muhat, muci] = expfit (x1);
+%! assert ([pd(1).mu], muhat);
+%! assert (paramci (pd(1)), muci);
+%! [phat, pci] = expfit (x2);
+%! assert ([pd(2).mu], muhat);
+%! assert (paramci (pd(2)), muci);
+%!test
 %! x = gamrnd (1, 1, 100, 1);
 %! pd = fitdist (x, "Gamma");
 %! [phat, pci] = gamfit (x);

inst/dist_wrap/makedist.m

@@ -136,7 +136,7 @@
       pd = [];
 
     case "exponential"
-      mu = 0;
+      mu = 1;
       while (numel (varargin) > 0)
         switch (tolower (varargin{1}))
           case "mu"
@@ -147,7 +147,7 @@
         endswitch
         varargin([1:2]) = [];
       endwhile
-      pd = [];
+      pd = ExponentialDistribution (mu);
 
     case "gamma"
       a = 1;
@@ -532,6 +532,13 @@
 
 ## Test output
 %!test
+%! pd = makedist ("exponential");
+%! assert (class (pd), "ExponentialDistribution");
+%! assert (pd.mu, 1);
+%!test
+%! pd = makedist ("exponential", "mu", 5);
+%! assert (pd.mu, 5);
+%!test
 %! pd = makedist ("gamma");
 %! assert (class (pd), "GammaDistribution");
 %! assert (pd.a, 1);