Loading binary tensor in matlab

binload.m

function r = binload(fid,type,xsize,loadall,order)
% BINLOAD loads a binary tensor from file. 
%
% r = binload(fid,type,xsize,loadall=1,order='column')
%
% This function loads tensor data from a file stored in binary form, it allows to reload
% data from numpy when saved with tofile. Also a raw image file can be loaeded. For example
% an RGB image stored by row is: 
%
% A = binload(fid,'uint8',[height,width,3],'row')
%
% % but clearly
%
% A = binload(fid,'uint8',[3,width,height],'column')
%
% Arguments:
% - fid is the file identifier from fopen or a filename
% - type is the type of content compatible with fread (e.g. float64,int64...)
% - xsize is a vector of the data dimensions [s1,s2,...]
% - loadall forces to repeat the loading of elements of size xsize until the end of file, this menas
%   that the output has an extra dimension sX. This dimension goes at the beginning or at the
%   end of the xsize depending on the parameter order (see below)
% - order (bool) specifies the storage order 'column' or 'row', rember that Matlab is column,
%      and numpy is row
%
% Note: when loadall=1; row major the repetition of xsize is placed outer as first dimension, 
% while in col order it is inner and it is placed last.
%
% Verification: generate using ngrid and compare result with meshgrid
% interpolant
%
% Note: in comparison to fread we do not pass: precision, skip and
% machinefmt, but they can be added easily.
%
% Emanuele Ruffaldi 2016 <emanuele.ruffaldi@gmail.com>

if nargin == 3
    loadall = 1;
end

if nargin < 5
    order = 'column';
end

if ischar(fid)
    fid = fopen(fid,'r');
end

nl = prod(xsize);

if loadall
    r = fread(fid,[nl,Inf],type);
    n = size(r,2);
    r = r(:);
else
    r = fread(fid,nl,type);    
    n = 0;
end

if n == 0
    % we have exactly the content
    if strcmp(order,'column')
        r = reshape(r,xsize);
    else
        r = reshape(r,xsize(end:-1:1));
        r = permute(r,length(xsize):-1:1);
    end
else
    % add one dimension
    % we have n blocks with given columns: 
    % row order = blocks are outer
    % col order = blocks are inner
    if strcmp(order,'column')
        r = reshape(r,[xsize n]);
    else
        xsize = [n xsize];
        r = reshape(r,xsize(end:-1:1));
        r = permute(r,length(xsize):-1:1);
    end
end