boxplots.m

function boxplots(x,varargin)
% boxplots(x,catnames,dataname,notch,sym,vert,whis)
% Create a boxplot using the columns of x.
% The optional character matrix catnames contains
% categorical names for the data sets and it has
% as many rows as there are boxplots.
% The third argument is an optional character
% string for the response variable name.  Additional arguments
% correspond to those provided for the standard boxplot function.
% Use boxplot if you don't want to modify the labels.

% In accordance with the API for boxplot, all arguments must
% be supplied if more than three arguments are needed. For instance,
% notch and sym must be specified if vert is to be used.

% For example, four horizontal nochted boxplots with labels
% are created with this code:
% x = rand(20,4);
% catnames = strvcat('first','second','third','fourth');
% notch = 1;
% sym = '+';
% vert = 0;
% boxplots(x,catnames,'random data',notch,sym,vert)
%
% Use boxprep if there are multiple data sets that need
% to be merged first.
% December 12, 2002. , November 12, 2003, H. Gollwitzer
% November 24, 2003. Cleaned up switch statements

if not(exist('boxplot'))
	error('Statistics Toolbox not installed')
end
if nargin < 1
	error('No data.')
end
% Set up defaults
notch = 0; % no notch
sym = '+';
vert = 1; % vertical alignment
whis = 1.5;
% How many boxplots?
[m,n] = size(x);
if min(m,n) == 1 
    n=1;
end
% n is number of categories
argcount = length(varargin);
switch argcount
	case 0
		catnames = '';
		dataname = '';
	case 1
		catnames = varargin{1};
		dataname = '';
	otherwise
		[catnames,dataname] = deal(varargin{1:2});
end

switch argcount
case 0:2
	;
case 3
	notch = varargin{3};
case 4
	[notch,sym] = deal(varargin{3:4});
case 5  
	[notch,sym,vert] = deal(varargin{3:5});
case 6
	[notch,sym,vert,whis] = deal(varargin{3:6});
otherwise
	warning('More arguments than expected.')
end
% *** The call ***
boxplot(x,notch,sym,vert,whis); 
% Take care of any ornamentation
if (size(catnames,1) == n) & ischar(catnames)
	z = cell(1,n);
	for k = 1:n
		z{k} = deblank(catnames(k,:)); % remove trailing blanks
	end
	if vert % The usual orientation
		xlabel('');
		set(gca,'XTicklabel',z); % use catnames in place of numerical tick labels.
		if not(isempty(dataname))
			ylabel(dataname);
		end;
	else % horizontal
		ylabel('');
		set(gca,'YTicklabel',z); % use catnames in place of numerical tick labels.
		if not(isempty(dataname))
			xlabel(dataname);
		end;
	end
end