nt_double2int

nt_double2int() - recode/decode double as integer to save space

 z=nt_double2int(x,intsize): recode double as integer
   z: coded data
   x: data to code (matrix or array of matrices)
   intsize: [default: 'int16']

 x=nt_double2int(z,indices): decode back to double
   x: decoded data
   z: coded data
   indices: indices of rows/columns [default: all]
     indices{1}: rows to keep
     indices{2}: columns to keep

 Data are coded as a structure including a matrix of integers together with
 min and max of each column:
   z.ints: data scaled and coded as ints
   z.min: min of original data
   z.max: max of original data
   z.intsize: integer type (e.g. 'int16')

 They can also consist of a cell array of such structures.
 
 NoiseTools

0001 function z=nt_double2int(x,param)
0002 %nt_double2int() - recode/decode double as integer to save space
0003 %
0004 % z=nt_double2int(x,intsize): recode double as integer
0005 %   z: coded data
0006 %   x: data to code (matrix or array of matrices)
0007 %   intsize: [default: 'int16']
0008 %
0009 % x=nt_double2int(z,indices): decode back to double
0010 %   x: decoded data
0011 %   z: coded data
0012 %   indices: indices of rows/columns [default: all]
0013 %     indices{1}: rows to keep
0014 %     indices{2}: columns to keep
0015 %
0016 % Data are coded as a structure including a matrix of integers together with
0017 % min and max of each column:
0018 %   z.ints: data scaled and coded as ints
0019 %   z.min: min of original data
0020 %   z.max: max of original data
0021 %   z.intsize: integer type (e.g. 'int16')
0022 %
0023 % They can also consist of a cell array of such structures.
0024 %
0025 % NoiseTools
0026 
0027 nt_greetings;
0028 
0029 
0030 if iscell(x)
0031     for iChunk=1:numel(x)
0032         z{iChunk}=nt_double2int(x{iChunk},param);
0033     end
0034     return
0035 end
0036 
0037 if isfloat(x) % code to integer
0038 
0039     if nargin<2; param='int16'; end
0040     intsize=param;
0041     sz=size(x);
0042     if ndims(x)>2; x=x(:,:); end
0043    
0044     z.ints=zeros(size(x),intsize);
0045     z.min=zeros(1,size(x,2));
0046     z.max=zeros(1,size(x,2));
0047     z.intsize=intsize;
0048     
0049     % recode columns individually
0050     for iCol=1:size(x,2);
0051         z.min(iCol)=min(x(:,iCol));        
0052         z.max(iCol)=max(x(:,iCol));
0053         z.ints(:,iCol)= double(intmin(intsize)) + ...
0054             (x(:,iCol) - z.min(iCol)) * ...
0055             ( double(intmax(intsize))-double(intmin(intsize)) ) /...
0056             ( z.max(iCol)-z.min(iCol) ); % automatically coerced to intsize
0057     end
0058     z.ints=reshape(z.ints,sz);
0059     
0060 else % decode back to double
0061     
0062     assert(isstruct(x), '!');
0063     intsize=x.intsize;
0064     sz=size(x.ints);
0065     if ndims(x.ints)>2; x.ints=x.ints(:,:); end
0066 
0067     if nargin<2; param=[]; end
0068     indices=param;
0069     
0070     if isempty(indices); 
0071         
0072         % default: decode all
0073         z=zeros(size(x.ints));
0074         for iCol=1:size(x.ints,2)
0075             z(:,iCol) = x.min(iCol) + ...
0076                 (x.max(iCol)-x.min(iCol)) / (double(intmax(intsize))-double(intmin(intsize))) * (double(x.ints(:,iCol))-double(intmin(intsize)));
0077         end
0078         z=reshape(z,sz);
0079         
0080     else
0081         % select rows and/or columns
0082         if numel(indices)<2; indices{2}=[]; end
0083         if isempty(indices{1}); indices{1}=1:size(x.ints,1); end
0084         if isempty(indices{2}); indices{2}=1:size(x.ints,2); end
0085         
0086         z=zeros(numel(indices{1}),numel(indices{2}));
0087         
0088         for idx=1:numel(indices{2})
0089             iCol=indices{2}(idx);
0090             z(:,idx) = x.min(iCol) + ...
0091                 (x.max(iCol)-x.min(iCol)) / (double ( double(intmax(intsize))-double(intmin(intsize)))) * (double(x.ints(indices{1},iCol))-double(intmin(intsize)));
0092         end
0093         
0094         
0095         if numel(sz)>2 && numel(indices{2})<size(x.ints,2)
0096             warning('output data has not been reshaped');
0097         else
0098             z=reshape(z,[numel(indices{1}),numel(indices{2})]);
0099         end
0100         
0101     end
0102     
0103 end
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