cell2float(C, Filler, StopOnError)

function [M, Q] = cell2float(C, Filler, StopOnError)
% CELL2FLOAT - converts cell array into scalar float array
%    M = CELL2FLOAT(C) returns a float array M with the same size as the
%    cell array C. C can be any N-dimensional cell array. Cells of C that
%    contain a scalar float (single or double) are put in corresponding
%    locations of M. Cells that contain other datatypes (e.g., strings,
%    arrays, empty, integers, etc.) yield NaNs in the corresponding
%    locations of M. 
%
%    M = CELL2FLOAT(C,F) uses the value F instead of NaN to fill these
%    latter locations. F should be a scalar float (single or double). 
%
%    M = CELL2FLOAT(C,F,'error') will cause the program to error if a cell
%    does not contain a scalar float. If F is empty ([]), NaN will be used
%    as the filler value.
%
%    [M,Q] = CELL2FLOAT(C, ..) returns a logical array Q with logical ones
%    (true) where the values of C are floats, and logical zeros (false)
%    elsewhere.
%
%    Example:
%      C = {single(1) 2 'x' [] ; 1:3 complex(1,2) uint8(1) Inf}
%      M = cell2float(C)
%      % -> [ 1.00  2.00          NaN  NaN ;         
%      %       NaN  1.00 + 2.00i  NaN  Inf  ]
%
%      cell2float({1 2 [] 3 [] 5},999)
%      % -> [ 1  2  999  3  999  5 ]
%
%      cell2float({1,2,'x'},[],'error')
%      % ??? Error using ==> cell2float at 80
%      % Not all cells contain a scalar float.
%
%    See also CELL2MAT, CELLFUN, NUM2CELL

% for Matlab R13+
% version 4.0 (jan 2009)
% (c) Jos van der Geest
% email: [e-mail]
%
% History
% 1.0 (sep 2007) created 
% 2.0 (apr 2008) added help and updated for the File Exchange
% 2.1 (apr 2008) fixed spelling errors
% 2.2 (may 2008) fixed spelling errors
% 3.0 (dec 2009) per suggestion of Oleg Komarov, I added the option that an
%     error is thrown, when a non-scalar is encountered, instead of filling
%     it with NaN
% 4.0 (jan 2010) 

% check the inputs
error(nargchk(1,3,nargin)) ;

% first input should be cell array
if ~iscell(C), 
   error('cell2float:BadInput','First input should be cell array') ; 
end

if nargin<2 || isempty(Filler),    
    % default filler value: NaN
    Filler = NaN ;
elseif numel(Filler) ~= 1 || ~isfloat(Filler)
    % filler should be a scalar float
    error('cell2float:BadInput','2nd argument should be a scalar float.') ;
end

if nargin<3,
    StopOnError = false ;
else
    if ~ischar(StopOnError) || ~isequal(strmatch(lower(StopOnError), 'error'),1)
        error('cell2float:BadInput','3rd argument should be the string ''error''.') ;
    end
    StopOnError = true ;
end

% pre-allocate the matrix with the filler value
M = repmat(Filler,size(C)) ;  

% which cell elements are scalar doubles or singles?
Q = cellfun('prodofsize',C)==1 & ...
    (cellfun('isclass',C,'double') | cellfun('isclass',C,'single')) ;

if StopOnError && ~all(Q(:)),
    error('cell2float:NonScalerCells','Not all cells contain a scalar float.') ;
end

% put these in M in the corresponding locations
M(Q) = [C{Q}] ;