straightline

 function f = straightline(value,direction,linestyle,rng)

 <value> is a vector of values
 <direction> is
   'h' or 'y' means horizontal lines
   'v' or 'x' means vertical lines
 <linestyle> is like 'r:'
 <rng> (optional) is [A B] with the range to restrict to.
   for example, when <direction> is 'h', then <rng> being
   [1 3] means to restrict the horizontal extent of the line
   to between 1 and 3.  if [] or not supplied, use the 
   full range of the current axis.

 draw lines on the current figure.
 return a vector of handles.

 example:
 figure;
 h = straightline(randn(1,10),'v','r-');
 set(h,'LineWidth',2);

0001 function f = straightline(value,direction,linestyle,rng)
0002 
0003 % function f = straightline(value,direction,linestyle,rng)
0004 %
0005 % <value> is a vector of values
0006 % <direction> is
0007 %   'h' or 'y' means horizontal lines
0008 %   'v' or 'x' means vertical lines
0009 % <linestyle> is like 'r:'
0010 % <rng> (optional) is [A B] with the range to restrict to.
0011 %   for example, when <direction> is 'h', then <rng> being
0012 %   [1 3] means to restrict the horizontal extent of the line
0013 %   to between 1 and 3.  if [] or not supplied, use the
0014 %   full range of the current axis.
0015 %
0016 % draw lines on the current figure.
0017 % return a vector of handles.
0018 %
0019 % example:
0020 % figure;
0021 % h = straightline(randn(1,10),'v','r-');
0022 % set(h,'LineWidth',2);
0023 
0024 % input
0025 if ~exist('rng','var') || isempty(rng)
0026   rng = [];
0027 end
0028 
0029 % hold on
0030 prev = ishold;
0031 hold on;
0032 
0033 % do it
0034 ax = axis;
0035 f = zeros(1,length(value));
0036 switch direction
0037 case {'h' 'y'}
0038   if isempty(rng)
0039     rng = ax(1:2);
0040   end
0041   for p=1:length(value)
0042     f(p) = plot(rng,[value(p) value(p)],linestyle);
0043   end
0044 case {'v' 'x'}
0045   if isempty(rng)
0046     rng = ax(3:4);
0047   end
0048   for p=1:length(value)
0049     f(p) = plot([value(p) value(p)],rng,linestyle);
0050   end
0051 otherwise
0052   error('invalid <direction>');
0053 end
0054 
0055 % hold off
0056 if ~prev
0057   hold off;
0058 end