float indices in Python bindings

[rmchurch]

I would recommend supporting floats for indexing with the Python Adios bindings, similar to the h5py package for HDF5 files in Python. See below.

In h5py, the following works:
In [25]: file_path5='file.h5'
In [26]: f5 = h5py.File(file_path5)
In [27]: d1 = f5[data_path][:,1,:]
In [28]: d2 = f5[data_path][:,1.,:]

In adios, we get an error when using a float to slice:
In [29]: file_path=''file.bp'
In [30]: f = ad.file(file_path)
In [31]: d1 = f[data_path][:,1,:]

In [32]: d2 = f[data_path][:,1.,:]

AttributeError Traceback (most recent call last)
in ()
----> 1 d2 = f[data_path][:,1.,:]

adios.pyx in adios.var.getitem (adios.cpp:14190)()

AttributeError: 'float' object has no attribute 'step'

[ax3l]

Update: OT, now in #56
It would also be great if we could bring the general interface closer to h5py in general.

Some points:

• .file -> .File (upper case in the read API)
• .attr -> .attrs renaming
• emulating that each group and each variable object can in turn again have a .attrs member (that simply checks the global list of attributes for attributes that share the same prefix)

[jychoi-hpc]

Just wondering what is the correct way to handle if the index is 1.5. For an example,
f[data_path][:,1.5,:]
Raise an error? Round up to 2? or Cut to 1?

[jychoi-hpc]

emulating that each group and each variable object can in turn again have a .attrs member (that simply checks the global list of attributes for attributes that share the same prefix)

Can you give any example? I just need to have a clear picture for this.

[ax3l]

@yyalli Of course, I am glad to provide one! -> migrated to #56

[rmchurch]

@yyalli If the index is 1.5, I think the correct behavior should be cut to 1 (you should just do an int(index) call on any slicing index put into the getitem method. This is what h5py does).

[jychoi-hpc]

Hi, Axel,

Sorry for my late reply.

I partially implemented attaching attrs to variables. Recent examples can
be found in wrapper/numpy/tests/test_adios_attribute.py

However, I haven't implemented the group concept yet. Please try the
example and let me know if this update works for you or not.

On Mon, Dec 14, 2015 at 4:10 AM, Axel Huebl notifications@github.com
wrote:

@yyalli https://github.com/yyalli ping :)

—
Reply to this email directly or view it on GitHub
#53 (comment).

Jong Youl Choi
Scientific Data Group
Computer Science and Math Division
Oak Ridge National Laboratory
Homepage: http://www.ornl.gov/~jyc/

[jychoi-hpc]

Michael, Sorry for this late update.

I am still working on this but planning to finish by the end of this year
:) I will let you know soon.

On Thu, Oct 8, 2015 at 11:39 AM, Michael Churchill <notifications@github.com

wrote:

@yyalli https://github.com/yyalli If the index is 1.5, I think the
correct behavior should be cut to 1 (you should just do an int(index) call
on any slicing index put into the getitem method. This is what h5py does).

—
Reply to this email directly or view it on GitHub
#53 (comment).

Jong Youl Choi
Scientific Data Group
Computer Science and Math Division
Oak Ridge National Laboratory
Homepage: http://www.ornl.gov/~jyc/

[jychoi-hpc]

Now indexing can take floats and numpy boolean arrays too.