How to change the type when creating HDF5 attributes.

Hi all,

I want to create attributes for a HDF5 file like this which is read from HDFView:

and here is my Matlab code:

h5writeatt('tt.h5','/tide','Dimension', "XY");
h5writeatt('tt.h5','/tide','Discretization', [2.0 3.0]);
h5writeatt('tt.h5','/tide','Origin', [-1.0 -1.0]);
h5writeatt('tt.h5','/tide','Max Buffer Size', int32(4));
h5writeatt('tt.h5','/tide','Cell Centered', "TRUE");
h5writeatt('tt.h5','/tide','Time Units', "d");

then I read it in HDFView, and the result is:

How shoud I change the type when creating the attributes? And the type of "Transient" is like BOOL, how shoud I set this type?

Thanks,

Peter

[Les Beckham]

If I read your question correctly you are primarily concerned with the type of the "Transient" attribute, but you didn't show the code you used to write that attribute. What was the type of the data you wrote to that attribute? Was it logical or a string or a number?

[Kang Peng]

The code in the question is already all the code for attribute writing, and I put out the whole code for creating the HDF5 file.

D = zeros(26,3,636);
for i = 1:26
    a = i*3-2;
    E = Pressure([a:a+2],:);
    D(i,:,:) = E;
end
h5create('tt.h5', '/tide/Data', [26 3 636]);
h5write('tt.h5','/tide/Data',D);
h5create('tt.h5', '/tide/Time', 26);
h5write('tt.h5','/tide/Time',Time);
h5writeatt('tt.h5','/tide','Dimension', "XY");
h5writeatt('tt.h5','/tide','Discretization', [2.0 3.0]);
h5writeatt('tt.h5','/tide','Origin', [-1.0 -1.0]);
h5writeatt('tt.h5','/tide','Max Buffer Size', int32(4));
h5writeatt('tt.h5','/tide','Transient', "TRUE");
h5writeatt('tt.h5','/tide','Time Units', "d");

But I don't know how to modify the type of the attribute. The first picture is the type of each attribute I want to set, how can I write the type of the attribute?

Answer 1

[Les Beckham]

I don't have any hd5 files to test this with, but I suspect that if you change this

h5writeatt('tt.h5','/tide','Transient', "TRUE");

to this

h5writeatt('tt.h5','/tide','Transient', true);

you may achieve what you want.

"TRUE" is not a boolean (logical) value, it is a string.

[Kang Peng]

I've change "TRUE" to true, but the error shows "not support 'logical' as an attribute data type".

[Les Beckham]

Interesting. I wonder why that isn't supported. This does agree with the documentation which says the attribute values is "specified as a character vector, string scalar, or numeric value".

I was hoping this was the solution. I'm afraid I don't have any experience with h5writeatt so I won't be much help beyond this initial guess.

Hopefully someone else can help.

You might try just using a numeric 1/0 instead of true/false, but I suspect that will come out as a double. Using a string was definitely not going to work.

[Kang Peng]

That's right the type is also not ENUM if I use 1/0 isntead of true/false.

Thanks for answering my question.

[Les Beckham]

You are welcome. Sorry it didn't help.

Good luck.

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