Question

I can’t seem to find any standard functions for serializing data. I have a large 128×51 array that I need need to store in a single database field. Without some kind of serializing, things will be problematic.

Whats the best way to solve this? I don’t use matlab quite that much so I’m not familiar with standard procedures…

Answer 1

One possibility is to use the TYPECAST function to convert numeric values into UINT8 bytes (only works for full, non-complex numeric values).

Note that the matrix has to be reshaped into a vector prior to serialization, thus its size will also have to be separately stored (or even serialized using the same process):

%# sample matrix
M = rand(3,4);

%# convert
b_sz = typecast(size(M),'uint8');   %# serialized matrix size
b = typecast(M(:),'uint8');         %# serialized vector

Now you can store b and b_sz into the database as sequences of bytes (integers in the range [0,255])

>> whos b b_sz
  Name       Size            Bytes  Class    Attributes

  b         96x1                96  uint8              
  b_sz      16x1                16  uint8          

Next, when you retrieve those values from DB, you can convert them back to double values using the inverse procedure, and reshape the matrix to its original size:

MM = reshape(typecast(b,'double'), typecast(b_sz,'double'));

%# compare against original matrix
isequal(M,MM)

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Optionally, if your database does not support array types, you can just convert the byte sequence as string, and store it in a VARCHAR type of field:

%# as string
str = sprintf('%d ',b);

%# recover bytes from string
b = uint8(str2num(str));