Mercurial > hg > octave-lyh
annotate scripts/statistics/base/ppplot.m @ 11523:fd0a3ac60b0e
update copyright notices
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Fri, 14 Jan 2011 05:47:45 -0500 |
| parents | e151e23f73bc |
| children | 6b2f14af2360 |
| rev | line source |
|---|---|
| 11523 | 1 ## Copyright (C) 1995-2011 Kurt Hornik |
| 3426 | 2 ## |
| 3922 | 3 ## This file is part of Octave. |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6 ## under the terms of the GNU General Public License as published by | |
| 7016 | 7 ## the Free Software Foundation; either version 3 of the License, or (at |
| 8 ## your option) any later version. | |
| 3426 | 9 ## |
| 3922 | 10 ## Octave is distributed in the hope that it will be useful, but |
| 3200 | 11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 3426 | 13 ## General Public License for more details. |
| 14 ## | |
| 3200 | 15 ## You should have received a copy of the GNU General Public License |
| 7016 | 16 ## along with Octave; see the file COPYING. If not, see |
| 17 ## <http://www.gnu.org/licenses/>. | |
| 3200 | 18 |
| 3453 | 19 ## -*- texinfo -*- |
| 20 ## @deftypefn {Function File} {[@var{p}, @var{y}] =} ppplot (@var{x}, @var{dist}, @var{params}) | |
| 21 ## Perform a PP-plot (probability plot). | |
| 3200 | 22 ## |
| 3453 | 23 ## If F is the CDF of the distribution @var{dist} with parameters |
| 24 ## @var{params} and @var{x} a sample vector of length @var{n}, the | |
| 25 ## PP-plot graphs ordinate @var{y}(@var{i}) = F (@var{i}-th largest | |
| 26 ## element of @var{x}) versus abscissa @var{p}(@var{i}) = (@var{i} - | |
| 27 ## 0.5)/@var{n}. If the sample comes from F, the pairs will | |
| 28 ## approximately follow a straight line. | |
| 3200 | 29 ## |
| 3453 | 30 ## The default for @var{dist} is the standard normal distribution. The |
| 31 ## optional argument @var{params} contains a list of parameters of | |
| 32 ## @var{dist}. For example, for a probability plot of the uniform | |
| 33 ## distribution on [2,4] and @var{x}, use | |
| 34 ## | |
| 35 ## @example | |
| 36 ## ppplot (x, "uniform", 2, 4) | |
| 37 ## @end example | |
| 3200 | 38 ## |
| 6754 | 39 ## @noindent |
| 40 ## @var{dist} can be any string for which a function @var{dist_cdf} | |
| 41 ## that calculates the CDF of distribution @var{dist} exists. | |
| 42 ## | |
| 3200 | 43 ## If no output arguments are given, the data are plotted directly. |
| 3453 | 44 ## @end deftypefn |
| 3200 | 45 |
| 5428 | 46 ## Author: KH <Kurt.Hornik@wu-wien.ac.at> |
| 3456 | 47 ## Description: Perform a PP-plot (probability plot) |
| 3200 | 48 |
| 3979 | 49 function [p, y] = ppplot (x, dist, varargin) |
| 3426 | 50 |
| 3200 | 51 if (nargin < 1) |
| 6046 | 52 print_usage (); |
| 3200 | 53 endif |
| 3426 | 54 |
| 4030 | 55 if (! isvector (x)) |
|
11436
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
56 error ("ppplot: X must be a vector"); |
| 3200 | 57 endif |
| 58 | |
| 59 s = sort (x); | |
| 60 n = length (x); | |
| 61 p = ((1 : n)' - 0.5) / n; | |
| 62 if (nargin == 1) | |
| 4348 | 63 F = @stdnormal_cdf; |
| 3200 | 64 else |
|
11436
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
65 F = str2func (sprintf ("%scdf", dist)); |
| 3200 | 66 endif; |
| 67 if (nargin <= 2) | |
| 68 y = feval (F, s); | |
| 69 else | |
| 3979 | 70 y = feval (F, s, varargin{:}); |
| 3200 | 71 endif |
| 3426 | 72 |
| 3200 | 73 if (nargout == 0) |
| 6447 | 74 plot (p, y); |
| 3200 | 75 axis ([0, 1, 0, 1]); |
| 76 endif | |
| 77 | |
| 78 endfunction | |
|
11436
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
79 |
|
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
80 %% Test input validation |
|
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
81 %!error ppplot (); |
|
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
82 %!error ppplot (ones(2,2)); |
|
e151e23f73bc
Overhaul base statistics functions and documentation of same.
Rik <octave@nomad.inbox5.com>
parents:
7017
diff
changeset
|
83 |