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% floatread() - Read matrix from float file ssuming four byte floating point number
% Can use fseek() to read an arbitary (continguous) submatrix.
%
% Usage: >> a = floatread(filename,size,'format',offset)
%
% Inputs:
% filename - name of the file
% size - determine the number of float elements to be read and
% the dimensions of the resulting matrix. If the last element
% of 'size' is Inf, the size of the last dimension is determined
% by the file length. If size is 'square,' floatread() attempts
% to read a square 2-D matrix.
%
% Optional inputs:
% 'format' - the option FORMAT argument specifies the storage format as
% defined by fopen(). Default format ([]) is 'native'.
% offset - either the number of first floats to skip from the beginning of the
% float file, OR a cell array containing the dimensions of the original
% data matrix and a starting position vector in that data matrix.
%
% Example: % Read a [3 10] submatrix of a four-dimensional float matrix
% >> a = floatread('mydata.fdt',[3 10],'native',{[[3 10 4 5],[1,1,3,4]});
% % Note: The 'size' and 'offset' arguments must be compatible both
% % with each other and with the size and ordering of the float file.
%
% Author: Sigurd Enghoff, CNL / Salk Institute, La Jolla, 7/1998
%
% See also: floatwrite(), fopen()
% Copyright (C) Sigurd Enghoff, CNL / Salk Institute, La Jolla, 7/1998
%
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software
% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
% 04-26-99 modified by Sigurd Enghoff to handle variable-sized and
% multi-dimensional data.
% 07-08-99 modified by Sigurd Enghoff, FORMAT argument added.
% 02-08-00 help updated for toolbox inclusion -sm
% 02-14-00 added segment arg -sm
% 08-14-00 added size 'square' option -sm
% 01-25-02 reformated help & license, added links -ad
function A = floatread(fname,Asize,fform,offset)
if nargin<2
help floatread
return
end
if ~exist('fform') | isempty(fform)|fform==0
fform = 'native';
end
if ~exist('offset')
offset = 0;
end
fid = fopen(fname,'rb',fform);
if fid>0
if exist('offset')
if iscell(offset)
if length(offset) ~= 2
error('offset must be a positive integer or a 2-item cell array');
end
datasize = offset{1};
startpos = offset{2};
if length(datasize) ~= length(startpos)
error('offset must be a positive integer or a 2-item cell array');
end
for k=1:length(datasize)
if startpos(k) < 1 | startpos(k) > datasize(k)
error('offset must be a positive integer or a 2-item cell array');
end
end
if length(Asize)> length(datasize)
error('offset must be a positive integer or a 2-item cell array');
end
for k=1:length(Asize)-1
if startpos(k) ~= 1
error('offset must be a positive integer or a 2-item cell array');
end
end
sizedim = length(Asize);
if Asize(sizedim) + startpos(sizedim) - 1 > datasize(sizedim)
error('offset must be a positive integer or a 2-item cell array');
end
for k=1:length(Asize)-1
if Asize(k) ~= datasize(k)
error('offset must be a positive integer or a 2-item cell array');
end
end
offset = 0;
jumpfac = 1;
for k=1:length(startpos)
offset = offset + jumpfac * (startpos(k)-1);
jumpfac = jumpfac * datasize(k);
end
elseif length(offset) > 1
error('offset must be a positive integer or a 2-item cell array');
end
% perform the fseek() operation
% -----------------------------
stts = fseek(fid,4*offset,'bof');
if stts ~= 0
error('floatread(): fseek() error.');
return
end
end
% determine what 'square' means
% -----------------------------
if ischar('Asize')
if iscell(offset)
if length(datasize) ~= 2 | datasize(1) ~= datasize(2)
error('size ''square'' must refer to a square 2-D matrix');
end
Asize = [datsize(1) datasize(2)];
elseif strcmp(Asize,'square')
fseek(fid,0,'eof'); % go to end of file
bytes = ftell(fid); % get byte position
fseek(fid,0,'bof'); % rewind
bytes = bytes/4; % nfloats
froot = sqrt(bytes);
if round(froot)*round(froot) ~= bytes
error('floatread(): filelength is not square.')
else
Asize = [round(froot) round(froot)];
end
end
end
A = fread(fid,prod(Asize),'float');
else
error('floatread() fopen() error.');
return
end
% fprintf(' %d floats read\n',prod(size(A)));
% interpret last element of Asize if 'Inf'
% ----------------------------------------
if Asize(end) == Inf
Asize = Asize(1:end-1);
A = reshape(A,[Asize length(A)/prod(Asize)]);
else
A = reshape(A,Asize);
end
fclose(fid);
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