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subsref.m
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Tue, Feb 11, 14:16

subsref.m
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function varargout=subsref(obj,subs)
% SUBSREF Subscripted reference
% An overloaded function...
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
%
% $Id: subsref.m 4136 2010-12-09 22:22:28Z guillaume $
if isempty(subs), return; end
switch subs(1).type
case '{}'
error('Cell contents reference from a non-cell array object.');
case '.'
varargout = access_fields(obj,subs);
return;
end
if numel(subs)~=1, error('Expression too complicated'); end;
dim = [size(obj) ones(1,16)];
nd = find(dim>1,1,'last')-1;
sobj = struct(obj);
if ~numel(subs.subs)
[subs.subs{1:nd+1}] = deal(':');
elseif length(subs.subs) < nd
l = length(subs.subs);
dim = [dim(1:(l-1)) prod(dim(l:end))];
if numel(sobj) ~= 1
error('Can only reshape simple file_array objects.');
else
if numel(sobj.scl_slope)>1 || numel(sobj.scl_inter)>1
error('Can not reshape file_array objects with multiple slopes and intercepts.');
end
sobj.dim = dim;
end
end
di = ones(16,1);
args = cell(1,length(subs.subs));
for i=1:length(subs.subs)
if ischar(subs.subs{i})
if ~strcmp(subs.subs{i},':'), error('This shouldn''t happen....'); end
if length(subs.subs) == 1
args{i} = 1:prod(dim); % possible overflow when int32()
k = 0;
for j=1:length(sobj)
sobj(j).dim = [prod(sobj(j).dim) 1];
sobj(j).pos = [k+1 1];
k = k + sobj(j).dim(1);
end
else
args{i} = 1:dim(i);
end
else
args{i} = subs.subs{i};
end
di(i) = length(args{i});
end
if length(sobj)==1
t = subfun(sobj,args{:});
else
dt = datatypes;
dt = dt([dt.code]==sobj(1).dtype); % assuming identical datatypes
t = zeros(di',func2str(dt.conv));
for j=1:length(sobj)
ps = [sobj(j).pos ones(1,length(args))];
dm = [sobj(j).dim ones(1,length(args))];
for i=1:length(args)
msk = find(args{i}>=ps(i) & args{i}<(ps(i)+dm(i)));
args2{i} = msk;
args3{i} = double(args{i}(msk))-ps(i)+1;
end
t = subsasgn(t,struct('type','()','subs',{args2}),subfun(sobj(j),args3{:}));
end
end
varargout = {t};
%==========================================================================
% function t = subfun(sobj,varargin)
%==========================================================================
function t = subfun(sobj,varargin)
%sobj.dim = [sobj.dim ones(1,16)];
try
args = cell(size(varargin));
for i=1:length(varargin)
args{i} = int32(varargin{i});
end
t = file2mat(sobj,args{:});
catch
t = multifile2mat(sobj,varargin{:});
end
if ~isempty(sobj.scl_slope) || ~isempty(sobj.scl_inter)
slope = 1;
inter = 0;
if ~isempty(sobj.scl_slope), slope = sobj.scl_slope; end
if ~isempty(sobj.scl_inter), inter = sobj.scl_inter; end
if numel(slope)>1
slope = resize_scales(slope,sobj.dim,varargin);
t = double(t).*slope;
else
t = double(t)*slope;
end
if numel(inter)>1
inter = resize_scales(inter,sobj.dim,varargin);
end;
t = t + inter;
end
%==========================================================================
% function c = access_fields(obj,subs)
%==========================================================================
function c = access_fields(obj,subs)
sobj = struct(obj);
c = cell(1,numel(sobj));
for i=1:numel(sobj)
%obj = class(sobj(i),'file_array');
obj = sobj(i);
switch(subs(1).subs)
case 'fname', t = fname(obj);
case 'dtype', t = dtype(obj);
case 'offset', t = offset(obj);
case 'dim', t = dim(obj);
case 'scl_slope', t = scl_slope(obj);
case 'scl_inter', t = scl_inter(obj);
case 'permission', t = permission(obj);
otherwise
error(['Reference to non-existent field "' subs(1).subs '".']);
end
if numel(subs)>1
t = subsref(t,subs(2:end));
end
c{i} = t;
end
%==========================================================================
% function val = multifile2mat(sobj,varargin)
%==========================================================================
function val = multifile2mat(sobj,varargin)
% Convert subscripts into linear index
[indx2{1:length(varargin)}] = ndgrid(varargin{:},1);
ind = sub2ind(sobj.dim,indx2{:});
% Work out the partition
dt = datatypes;
dt = dt([dt.code]==sobj.dtype);
sz = dt.size;
try
mem = spm('Memory'); % in bytes, has to be a multiple of 16 (max([dt.size]))
catch
mem = 200 * 1024 * 1024;
end
s = ceil(prod(sobj.dim) * sz / mem);
% Assign indices to partitions
[x,y] = ind2sub([mem/sz s],ind(:));
c = histc(y,1:s);
cc = [0 reshape(cumsum(c),1,[])];
% Read data in relevant partitions
obj = sobj;
val = zeros(length(x),1,func2str(dt.conv));
for i=reshape(find(c),1,[])
obj.offset = sobj.offset + mem*(i-1);
obj.dim = [1 min(mem/sz, prod(sobj.dim)-(i-1)*mem/sz)];
val(cc(i)+1:cc(i+1)) = file2mat(obj,int32(1),int32(x(y==i)));
end
r = cellfun('length',varargin);
if numel(r) == 1, r = [r 1]; end
val = reshape(val,r);

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