vect2colon(vec, varargin)

% Usage: strvec = vect2colon(vec, options)
%
% Converts a vector into a string using MATLAB colon notation (single resolution).
%
% Options are:
%
% 'Delimiter'   -   'on','yes','off','no' {default on}  :  Including square brackets [] 
%                                     (or curly brackets {} when output's dimensions are not consistent)
%                                            'auto' by default.
% 'Sort'        -   'on','yes','off','no' {default off} :  Sort elements in ascending order
%                                            
% 'Class'       -   MATLAB classes
%
% 'Repeat'      -   'on','yes','off','no' {default on}  :  Keep repeated elements 
%
% MATLAB colon notation is a compact way to refer to ranges of matrix elements.
% It is often used in copy operations and in the creation of vectors and matrices.
% Colon notation can be used to create a vector as follows
%                           x = xbegin:dx:xend
%                                   or
%                          x2 = xbegin:xend
% where xbegin and xend are the range of values covered by elements of the x
% vector, and dx is the (optional) increment. If dx is omitted a value of 1
% (unit increment) is used. The numbers xbegin, dx, and xend need not be
% integers.
%
% Example 1:
% >> x = [  50 1000 1100 1200 2 3 4 5 6 10 20 30 40]
% >> vect2colon(x)
%
% ans =
%
% [ 50 1000:100:1200 2:6 10:10:40]
%
% or
%
% >> vect2colon(x, 'Sort', 'on')
%
% ans =
%
% [ 2:6 10:10:50 1000:100:1200]
%
% Example 2:
% >> x = [ 2 3 4 5 6 10 10.1 10.2 10.3 10.4 1000 1100 1200]
% >> s = vect2colon(x)
%
% s =
%
% [ 2:6 10:0.1:10.4 1000:100:1200 ]
%
% Example 3:
% >> x = [ 2 3 4 5 6 10 1000 1100 1200 10.1 10.2 10.3 10.4]
% >> s = vect2colon(x, 'Delimiter', 'no')
%
% s =
%
%  2:6 10 1000:100:1200 10.1:0.1:10.4
%
% See also:  mat2colon, eval, str2num
%
% Author: Javier Lopez-Calderon
% 2008-2011
%
% Feedback is appreciated.
% fixed bug where the increment is negative
% Checks numeric input
% Allows to keep repeated values

function strvec = vect2colon(vec, varargin)

p = inputParser;
p.FunctionName  = mfilename;
p.CaseSensitive = false;
p.addRequired('vec', @isnumeric);
p.addParamValue('Delimiter', 'auto', @ischar);
p.addParamValue('Sort', 'off', @ischar);
p.addParamValue('Class', 'single', @ischar);
p.addParamValue('Repeat', 'on', @ischar);
p.parse(vec, varargin{:});
strvec   = '';
if nargin<1
      help vect2colon
      return
end
if isempty(vec)
      if strcmp(p.Results.Delimiter,'yes') || strcmp(p.Results.Delimiter,'on')
            strvec = '[]';
      end
      return
end
[dime] = size(vec); % input size
if length(dime)>2
      error('Error: vect2colon only works for row or column vector. Use mat2colon instead.')
else
      if dime(1)>1 && dime(2)==1 % feb 2011
            apo = '''';
      elseif dime(1)==1 && dime(2)>=1
            apo = '';
      else
            error('Error: vect2colon only works for row or column vector. Use mat2colon instead.')
      end
end
if ismember({p.Results.Sort},{'yes','on'})
      if strcmpi(p.Results.Repeat,'off')
            vecuni      = unique(vec);    % repeated numbers are not allowed. sorted
      else
            vecuni = sort(vec);           % repeated numbers are allowed. sorted  --> previous bug
      end
else
      if ismember({p.Results.Repeat}, {'off','no'})
            [v a b] = unique(vec', 'first');
            ia = sort(a);
            vecuni = vec(ia); % repeated numbers are not allowed. no sorted
      else
            vecuni = vec; % repeated numbers are allowed. no sorted  --> previous bug
      end
end
dvec     = single(diff(vecuni));
holdc    = 0;
iexpress = 0;
k = 1;
while k <= numel(vecuni)
      if k>1 && k <= numel(vecuni) - 1
            if dvec(k) ~=0 && dvec(k) == dvec(k-1) && ~holdc
                  holdc = 1;
                  iexpress = iexpress + 1; % group counter
                  if dvec(k) ~= 1  % march 2011
                        if abs(abs(dvec(k))-pi)<1e-6
                              if dvec(k)<0
                                    dvstr = '-pi';
                              else
                                    dvstr = 'pi';
                              end
                        else
                              dvstr = num2str(dvec(k));
                        end
                        strvec = [ strvec ':' dvstr ':' ];     % starts a group with step>1
                  else
                        strvec = [ strvec ':' ];               % starts a group with step=1
                  end
            elseif (dvec(k) ~= dvec(k-1) || (dvec(k)==0 && dvec(k) == dvec(k-1))) && ~holdc
                  strvec   = [ strvec ' ' num2str(vecuni(k)) ];   % discret element
                  iexpress = iexpress + 1;
            elseif dvec(k) ~= dvec(k-1) && holdc
                  strvec = [ strvec num2str(vecuni(k)) ];       % ends a group with step=1
                  iexpress = iexpress + 1;
                  holdc    = 0;
                  dvec(k)  = 0; % since repeated numbers are not allowed...
            end
      else
            if holdc
                  strvec = [ strvec num2str(vecuni(k)) ];      % last element
            else
                  strvec = [ strvec ' ' num2str(vecuni(k)) ];  % first(last) element (discrete)
                  iexpress = iexpress + 1;
            end
      end
      k = k + 1;
end
if ismember({p.Results.Delimiter},{'yes','on'})
      strvec = [ '[' strvec ']' apo];
      return
end
if ((iexpress-1)>1 || ((iexpress-1)==1 && numel(vecuni)==2))...
            && (strcmp(p.Results.Delimiter,'auto'))
      strvec = [ '[' strvec ']' apo];
end
return