[Octave-bug-tracker] [bug #39938] pkg statistics: make qqplot ML compatible

[Muhali]

URL:
  <http://savannah.gnu.org/bugs/?39938>

                 Summary: pkg statistics: make qqplot ML compatible
                 Project: GNU Octave
            Submitted by: muhali
            Submitted on: Wed 04 Sep 2013 01:45:03 AM PDT
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

The attached patch makes qqplot accept a data array as a second argument, as
in ML. Its empirical quantiles are used for the plot.


--- /a/qqplot.m
+++ /b/qqplot.m
@@ -18,8 +18,9 @@
 
 ## -*- texinfo -*-
 ## @deftypefn  {Function File} address@hidden, @var{s}] =} qqplot (@var{x})
+## @deftypefnx {Function File} address@hidden, @var{s}] =} qqplot (@var{x},
@var{y})
 ## @deftypefnx {Function File} address@hidden, @var{s}] =} qqplot (@var{x},
@var{dist})
-## @deftypefnx {Function File} address@hidden, @var{s}] =} qqplot (@var{x},
@var{dist}, @var{params})
+## @deftypefnx {Function File} address@hidden, @var{s}] =} qqplot (@var{x},
@var{y}, @var{params})
 ## @deftypefnx {Function File} {} qqplot (@dots{})
 ## Perform a QQ-plot (quantile plot).
 ##
@@ -29,6 +30,9 @@
 ## largest element of x versus abscissa @var{q}(@var{i}f) = G((@var{i} -
 ## 0.5)/@var{n}).
 ##
+## If the second argument is a vector @var{y} the empirical CDF of @var{y}
+## is used as @var{dist}.
+##
 ## If the sample comes from F, except for a transformation of location
 ## and scale, the pairs will approximately follow a straight line.
 ##
@@ -65,7 +69,13 @@
   if (nargin == 1)
     f = @stdnormal_inv;
   else
-    if (   exist (invname = sprintf ("%sinv", dist))
+    if ( isvector(dist) )
+       if ( exist("empirical_inv") == 2 )
+         f = @(y) empirical_inv(y, dist) ;
+       else
+         f = @(y) empiricalinv(y, dist) ;
+       endif
+    elseif(   exist (invname = sprintf ("%sinv", dist))
         || exist (invname = sprintf ("%s_inv", dist)))
       f = str2func (invname);
     else
@@ -92,6 +102,7 @@
 
   if (nargout == 0)
     plot (q, s);
+    q_label = strrep(q_label, "_", "\_") ;
     xlabel (q_label);
     ylabel ("sample points");
   endif





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