I have never seen this before, but I have a file with a 1x1 dataset where the only value is a Array[3] of 64-bit floating point. I can see this using the HDFView tool, but no matter what I try, I get errors. Is there a special type I need to create for this to work?
Edit if I use H5Sget_simple_extent_npoints()
to get the number of data points, the result is 1. So, it appears to be 1 array of 3 elements.
The last thing I tried was manually reading 3 doubles:
hid_t dataset = ...; // open the dataset (dataset is valid)
double var[3];
hsize_t memdim[] = { 3 };
hid_t space = H5Screate_simple(1, memdim, nullptr); // (space is valid)
auto rc = H5Dread(dataset, H5T_NATIVE_DOUBLE, space, space, H5P_DEFAULT, &var[0]);
// rc = -1
Also tried just reading the whole dataset:
hid_t dataset = ...; // open the dataset (dataset is valid)
double var[3];
auto rc = H5Dread(dataset, H5T_NATIVE_DOUBLE, H5S_ALL, H5S_ALL, H5P_DEFAULT, &var[0]);
// rc = -1
Error text from the above tests:
HDF5-DIAG: Error detected in HDF5 (1.10.5) thread 17272:
#000: \hdf5-1.10.5\src\H5Dio.c line 199 in H5Dread(): can't read data
major: Dataset
minor: Read failed
#001: \hdf5-1.10.5\src\H5Dio.c line 467 in H5D__read(): unable to set up type info
major: Dataset
minor: Unable to initialize object
#002: \hdf5-1.10.5\src\H5Dio.c line 983 in H5D__typeinfo_init(): unable to convert between src and dest datatype
major: Dataset
minor: Feature is unsupported
#003: \hdf5-1.10.5\src\H5T.c line 4546 in H5T_path_find(): can't find datatype conversion path
major: Datatype
minor: Can't get value
#004: \hdf5-1.10.5\src\H5T.c line 4762 in H5T__path_find_real(): no appropriate function for conversion path
major: Datatype
minor: Unable to initialize object
I figured out that there is an array type that can be made that is required:
hsize_t size = { 3 };
hid_t type = H5Tarray_create(H5T_NATIVE_DOUBLE, 1, &size);
hid_t dataset = H5Dopen(...);
double var[3];
hsize_t memdim[] = { 1 }; // or how many arrays[3]'s to read
hid_t space = H5Screate_simple(1, memdim, nullptr);
auto rc = H5Dread(dataset, type, space, H5S_ALL, H5P_DEFAULT, &var[0]);