Obtaining very different results when guessing or passing object directly to $create_dataset()

[luigidolcetti]

Hi,

as mentioned in the title I am getting very different results when guessing data type, space, dims, and chunks with respect to passing directly an object to the create_dataset method. I attempted to identify my mistakes going through the method code but with poor results.
For example, if I do the following:

x <- data.frame(a=factor(letters[runif(n = 1E5,1,10)]),b=factor(letters[runif(n = 1E5,1,10)]))
dims <- hdf5r::guess_dim(x)
dtype <- hdf5r::guess_dtype(x,scalar=FALSE,string_len = Inf,ds_dim = dims)
nelem <- hdf5r::guess_nelem(x,dtype = dtype)
chunk_dims <- hdf5r::guess_chunks(space_maxdims = dims, dtype_size = nelem)
space <- hdf5r::guess_space(x,dtype = dtype,chunked = TRUE)

I get

> dims
[1] 100000
> dtype
Class: H5T_COMPOUND
Datatype: H5T_COMPOUND {
      H5T_ENUM {
         undefined integer;
         "a"                1;
         "b"                2;
         "c"                3;
         "d"                4;
         "e"                5;
         "f"                6;
         "g"                7;
         "h"                8;
         "i"                9;
      } "a" : 0;
      H5T_ENUM {
         undefined integer;
         "a"                1;
         "b"                2;
         "c"                3;
         "d"                4;
         "e"                5;
         "f"                6;
         "g"                7;
         "h"                8;
         "i"                9;
      } "b" : 1;
   }
> nelem
[1] 100000
> chunk_dims
[1] 0
> space
Class: H5S
Type: Simple
Dims: 100000
Maxdims: Inf

Clearly these results are going to cause troubles if I pass them to the method.... in particular, shouldn't be nelem give 2 instead of the number of rows of the data.frame?
On the contrary, if I do:

test <- hdf5r.Extra::h5TryOpen(tempfile(),'w')
test$create_dataset('auto',x)
test[['auto']]

more correctly I get:

Datatype: H5T_COMPOUND {
      H5T_ENUM {
         H5T_STD_U8LE;
         "a"                1;
         "b"                2;
         "c"                3;
         "d"                4;
         "e"                5;
         "f"                6;
         "g"                7;
         "h"                8;
         "i"                9;
      } "a" : 0;
      H5T_ENUM {
         H5T_STD_U8LE;
         "a"                1;
         "b"                2;
         "c"                3;
         "d"                4;
         "e"                5;
         "f"                6;
         "g"                7;
         "h"                8;
         "i"                9;
      } "b" : 1;
   }
Space: Type=Simple     Dims=100000     Maxdims=Inf
Chunk: 4096

I would appreaciate if you have any suggestion on how to reproduce the direct call results using instead the guessing path.

thank you in advance,
Luigi