How to save struct array into H5

Hi guys

I have this simple struct array wdata, has 4 fileds and saved as struct array

FieldA   =int32([1153 ; 1184 ; 1027;11 ]);
FieldB  ={'Exterior (static)', 'Intake',...
    'Intake manifold','test'};
FieldArray = [randn(1,ADIM0);randn(1,ADIM0);randn(1,ADIM0);randn(1,ADIM0)];
FieldC   =int32([11 ; 12 ; 13; 14]);
for i = 1:DIM0
    wdata(i).FieldA   =FieldA(i);
    wdata(i).FieldB  =FieldB(i);
    wdata(i).FieldArray = FieldArray(i);
    wdata(i).FieldC = FieldC;
end

I want to save wdata into h5 as compound, but I got stuck with memory assigning

can anyone help?

thansk

[Kat Lee]

Tried this, but failed

dim = 4;
file = H5F.create (fileName, 'H5F_ACC_TRUNC',...
    'H5P_DEFAULT', 'H5P_DEFAULT');

intType   =H5T.copy('H5T_NATIVE_INT');
sz(1)     = H5T.get_size(intType);
strType   = H5T.copy ('H5T_C_S1');
H5T.set_size (strType, 'H5T_VARIABLE');
sz(2)     =H5T.get_size(strType);

% array size
base_type_id = H5T.copy('H5T_NATIVE_DOUBLE');
arrayType = H5T.array_create(base_type_id, 1, ADIM0);
type_id = H5T.copy(arrayType);
H5T.set_size(type_id, 8);
sz(3) = H5T.get_size(arrayType);

intType   =H5T.copy('H5T_NATIVE_INT');
sz(4)     = H5T.get_size(intType);

offset(1)=0;
offset(2:4)=cumsum(sz(1:3));

memtype = H5T.create ('H5T_COMPOUND', sum(sz));
H5T.insert (memtype,...
    'FieldA',offset(1),intType);
H5T.insert (memtype,...
    'FieldB',offset(2), strType);
H5T.insert (memtype,...
    'FieldArray',offset(3), arrayType);
H5T.insert (memtype,...
    'FieldC',offset(4), intType);

filetype = H5T.create ('H5T_COMPOUND', sum(sz));
H5T.insert (filetype, 'FieldA', offset(1),intType);
H5T.insert (filetype, 'FieldB', offset(2), strType);
H5T.insert (filetype, 'FieldArray',offset(3), arrayType);
H5T.insert (filetype, 'FieldC',offset(4), intType);

space = H5S.create_simple (1,fliplr(dims), []);

dset = H5D.create (file, DATASET, filetype, space, 'H5P_DEFAULT');
H5D.write (dset, memtype, 'H5S_ALL', 'H5S_ALL', 'H5P_DEFAULT', flip(wdata));

Answer 1

[Shivam Lahoti]

Hi Kat Lee,

I can understand that you want to save the ‘wdata’ struct array into an HDF5 file as a compound datatype. However, you mentioned that you encountered issues with memory assignment.

You shall use the functions ‘h5create’ to create the HDF5 file and define the compound datatype and ‘h5write’ to write each struct element to the HDF5 file.

Execute this command into your MATLAB window to understand the implementation of both functions with the help of an example.

openExample('matlab/WriteToEntireDataSetExample') 

Refer to the documentation below for more clarity.

https://www.mathworks.com/help/matlab/ref/h5write.html

https://www.mathworks.com/help/matlab/ref/h5create.html

I hope this was helpful.

Regards,

Shivam Lahoti.