[obspy-users] pyasdf: tags and labels

Phil Cummins phil.cummins at anu.edu.au
Sun Feb 12 04:21:54 CET 2017


Hi again,

Quick answer to my own question:

In [1]: st=read()
In [2]: st
Out[2]:
3 Trace(s) in Stream:
BW.RJOB..EHZ | 2009-08-24T00:20:03.000000Z - 2009-08-24T00:20:32.990000Z 
| 100.0 Hz, 3000 samples
BW.RJOB..EHN | 2009-08-24T00:20:03.000000Z - 2009-08-24T00:20:32.990000Z 
| 100.0 Hz, 3000 samples
BW.RJOB..EHE | 2009-08-24T00:20:03.000000Z - 2009-08-24T00:20:32.990000Z 
| 100.0 Hz, 3000 samples

In [3]: for i,tr in enumerate(st):   # Insert labels in tr.stats.asdf
...    tr.stats.asdf = {}
...    tr.stats.asdf['labels'] = ['model%d' % i]
In [4]: ds = pyasdf.ASDFDataSet("tmp2")        # Open ASDF file
In [5]: ds.add_waveforms(st,tag='synthetic')    # Add waveforms
ln [6]: for sta in ds.ifilter(ds.q.labels == 'model1'):  # Retrieve 
model1 traces
...    print sta['synthetic'][0].stats

          network: BW
          station: RJOB
         location:
          channel: EHN
        starttime: 2009-08-24T00:20:03.000000Z
          endtime: 2009-08-24T00:20:32.990000Z
    sampling_rate: 100.0
            delta: 0.01
             npts: 3000
            calib: 1.0
          _format: ASDF
             asdf: AttribDict({'labels': [u'model1'], 'tag': 
u'synthetic', 'format_version': '1.0.0'})

So, putting the label in the asdf attribute dictionary before the call 
to ds.add_waveforms() seems to successfully store traces with the same 
tag but different labels. But is this the way it's supposed to work? 
I.e., behavior unlikely to change in future versions of ASDF?

Thanks,

- Phil

> Phil Cummins <mailto:phil.cummins at anu.edu.au>
> 12 February 2017 at 9:03 AM
> Hi,
>
> I'm not sure where else to ask questions about pyasdf - is there a 
> separate mailing list? Anyway, I thought I'd try here.
>
> I have a question about waveform tags vs. labels. My understanding is 
> that tags are a coarser way of organizing the data that affects how it 
> is stored on disk, and labels allow finer grained organization. E.g., 
> you might use a tag to distinguish data and synthetics, and then 
> labels to distinguish synthetics calculated for different earth models.
>
> However, I don't understand why this is useful if you can't store data 
> having the same tag but different labels. E.g., if I do:
>     ds.add_waveforms(obspy.read(), tag="synthetic",labels=["model1"])
> and then
>     ds.add_waveforms(obspy.read(), tag="synthetic",labels=["model2"])
>   I get an error:
>    ASDFWarning: Data 
> 'IU.SDV/IU.SDV.00.BHZ__2015-09-16T23:11:12__2015-09-16T23:21:42__synthetic' 
> already exists in file. Will not be added!
>
> So it would seem any add_waveform call must have a distinct tag. How 
> then can I give different labels to groups of traces within the same tag?
>
> E.g., could I set the label in the ASDF attributes of the trace before 
> calling add_waveforms, and then do the do the add_waveform call 
> without specifying the labels? Would my traces then get saved to the 
> same tag but with different labels?
>
> Thanks,
>
> - Phil
>
>
>
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-- 

Phil Cummins
Prof. Natural Hazards
Research School of Earth Sciences
Australian National University

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