Re: [Pytables-users] writing metadata

[Antonio V. <ant...@ti...>]

Hi Andre',

Il 25/06/2013 10:26, Andre' Walker-Loud ha scritto:
> Dear PyTables users,
> 
> I am trying to figure out the best way to write some metadata into some files I have.
> 
> The hdf5 file looks like
> 
> /root/data_1/stat
> /root/data_1/sys
> 
> where "stat" and "sys" are Arrays containing statistical and systematic fluctuations of numerical fits to some data I have.  What I would like to do is add another object
> 
> /root/data_1/fit
> 
> where "fit" is just a metadata key that describes all the choices I made in performing the fit, such as seed for the random number generator, and many choices for fitting options, like initial guess values of parameters, fitting range, etc.
> 
> I began to follow the example in the PyTables manual, in Section 1.2 "The Object Tree", where first a class is defined 
> 
> class Particle(tables.IsDescription):
> 	identity = tables.StringCol(itemsize=22, dflt=" ", pos=0)
> 	...
> 
> and then this class is used to populate a table.
> 
> In my case, I won't have a table, but really just want a single object containing my metadata.  I am wondering if there is a recommended way to do this?  The "Table" does not seem optimal, but I don't see what else I would use.
> 
> 
> Thanks,
> 
> Andre
> 

For leaf nodes (Tables, Array, ets) you can use the "attrs" attribute
set [1] as described in [2].
For group objects (like e.g. "root") you can use the "set_node_attr"
method [3] of File objects or "_v_attrs".


cheers

[1]
http://pytables.github.io/usersguide/libref/declarative_classes.html#attributesetclassdescr
[2]
http://pytables.github.io/usersguide/tutorials.html#setting-and-getting-user-attributes
[3]
http://pytables.github.io/usersguide/libref/file_class.html#tables.File.set_node_attr


-- 
Antonio Valentino