Is H5T_STD_I32BE the native int datatype for your platform? If no, you may want
to replace it by H5T_NATIVE_INT that will handle the proper int type.
Pierre
On Tue, Feb 10, 2015 at 04:29:35PM +0100, Sensei wrote:
> Dear all,
>
> I am sorry if I am posing a stupid question, but it seems I cannot really
> see how I can solve this on my own.
>
> The problem is understanding HDF5's possibility of creating datasets with
> slabs. For instance, write a 5x2 matrix with only one row set to { 42, 42 }.
>
> As far as I've learned reading the docs, I create the file, the dataspace
> with properties (5x2 of integers, for instance), and finally the dataspace
> itself. Then I can select the hyperslab and write to it.
>
> What I'm getting is junk. I suspect I'm writing what I'm not supposed to
> write, or reading where I've not intended to read, or both. Here's the dump:
>
> HDF5 "test.h5" {
> GROUP "/" {
> DATASET "dset" {
> DATATYPE H5T_STD_I32BE
> DATASPACE SIMPLE { ( 5, 2 ) / ( 5, 2 ) }
> DATA {
> (0,0): 704643072, 704643072,
> (1,0): 0, 0,
> (2,0): 16777216, 0,
> (3,0): 16777216, 0,
> (4,0): 16777216, 0
> }
> }
> }
> }
>
>
> I've played with my values, with count, offset and block, but I cannot grasp
> how it works.
>
> The code is below, it is commented with what I think each instruction does,
> and what each variable means.
>
>
> I really hope you can help me.
>
> Thank you!
>
>
>
> #include "hdf5.h"
>
> int main()
> {
> hid_t file_id, dataspace_id, dataset_id;
> herr_t status;
> int rank = 2; /* rank 2 tensor */
> hsize_t dims[2] = { 5, 2 }; /* 5 rows, 2 columns */
>
> hsize_t offset[2], stride[2], count[2], block[2];
>
> int newdata[3] = { 42, 42 };
>
> /* create file */
> file_id = H5Fcreate("test.h5", H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
>
> /* create dataspace */
> dataspace_id = H5Screate_simple(rank, dims, NULL);
>
> /* create dataset: the ACTUAL data */
> dataset_id = H5Dcreate(file_id, "/dset", H5T_STD_I32BE, dataspace_id,
> H5P_DEFAULT);
>
> /* slab properties */
> offset[0] = 1; /* row offset, select second row */
> offset[1] = 0; /* col offset, first column*/
>
> stride[0] = 1; /* select every 1 element, don't skip any row*/
> stride[1] = 1; /* and don't skip any elements on columns */
>
> count[0] = 1; /* select only one block per dimension */
> count[1] = 1; /* supposing 1 block means one entire row with this */
>
> block[0] = 1; /* size of the row block */
> block[1] = 3; /* column block size */
>
> /* select a slab */
> status = H5Sselect_hyperslab(dataspace_id, H5S_SELECT_SET,
> offset, stride, count, block);
>
> /* write! */
> status = H5Dwrite(dataset_id, H5T_STD_I32BE, H5S_ALL, H5S_ALL,
> H5P_DEFAULT,
> newdata);
>
> /* close dataset */
> status = H5Dclose (dataset_id);
>
> /* close dataspace */
> status = H5Sclose(dataspace_id);
>
> /* close file */
> status = H5Fclose(file_id);
>
> return 0;
> }
>
>
>
>
>
>
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--
-----------------------------------------------------------
Pierre de Buyl
KU Leuven - Institute for Theoretical Physics
T +32 16 3 27355
W http://pdebuyl.be/
-----------------------------------------------------------
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