Can we write a 2D array with dynamic shape?

[ziyuang]

I have a pointer to an array, and I know the shape. Can I write it as a 2D array? The following code will throw an exception of Impossible to write buffer of dimensions [2, 3] into dataset with n = 1 dimensions.:

float* raw = ...;
HighFive::DataSet dataset = file.createDataSet<float>("dataset", HighFive::DataSpace({2, 3}));
dataset.write(raw);

[ziyuang]

Closed: the solution is dataset.write((float**)raw);

[1uc]

The downside of this is that when presented with a float** we can't know if it's contiguous or not, e.g.

float ** array = (float**) malloc(n * sizeof(float*));
for(size_t i = 0; i < n; ++i) {
    array[i] = malloc(m * sizeof(float));
}

// vs
float * data = (float*) malloc(n*m * sizeof(float));
float ** array = (float**) malloc(n*sizeof(float*));

for(size_t i = 0; i < n; ++i) {
  array[i] = data + i * n;
}

Currently, HighFive doesn't seem to respect the possibility of non-contiguous pointer-to-pointer. Hence, it might work. However, the version I posted should be preferred.

[ziyuang]

Right, makes sense. Thanks.

[1uc]

There's write_raw which is probably the preferred solution in this case:

dataset.write_raw(raw);

See https://github.com/BlueBrain/HighFive/blob/master/src/examples/read_write_raw_ptr.cpp for a full example.

(Note that due to an asymmetry, there's no corresponding read_raw, it's just read with a pointer as argument.)