Helper Classes

tiskitpy.util_classes.CleanSequence

class tiskitpy.util_classes.CleanSequence

Bases: object

Routines to handle channel cleaning information lists.

Can store the information in Trace objects (Trace.stats[‘clean_sequence’]) and add or remove this information from the trace’s “location” code.

Can also match seed_ids independently of whether the clean sequence has been added to the location code.

Current clean_sequence codes are: - “-{seed_id}”: the given channel’s coherent part has been subtracted from this channel (DataCleaner) - “ROT” for simple rotation (CleanRotator) - “ZEROS” if selected data has been zeroed (TimeSpans)

In :classL`SpectralDensity` objects, they are stored in the property _clean_sequences and textually integrated in the input and output coordinates

In ReceiverFunction objects, CleanSequence is used to match channels with different levels of processing (it finds the original seed_id to compare)

A string representation can be generated using the string method

A string representation can be placed in or removed from a Trace/Stream’s seed id using the tag() and untag() methods

complete_seed_id(verbose=False)

Change string to a seed_id

Checks if there are 3 dots. If not, adds “missing” dots to beginning

static seed_id(tiskitpy_id)

Converts a tiskitpy_id to its base seed_id

Parameters:

tiskitpy_id (str) – tiskitpy_id

Returns:

the seed_id

Return type:

(str)

static seedid_tag(tr_st, out_format='minimal')

Add the CleanSequence’s string representation to Trace(s) seed_id

  • This is useful for using obspy to plot each channel separately

  • This is problematic if you want to link to the inventory (to correct for the instrument response, for example)

For example, if trace.stats.clean_sequence = [

‘XX.STA.00.BHX’, ‘XX.STA.00.BHY’, ‘XX.STA.00.BDH’, ‘XX.STA.01.BDH’]

and the input trace id is ‘XX.STA.00.BHZ’, the new trace id will be ‘XX.STA.00-X-Y-0_H-1_H.BHZ’

static seedid_untag(tr_st)

Remove the CleanSequence’s string representation from the Trace(s) seed_id

  • This is useful for linking to the inventory (for example, for the instrument response)

  • This is problematic for using obspy.plot() (plots cleaned channels on same line as uncleaned)

Parameters:

tr_st (obspy.core.Trace or obspy.core.Trace) – Trace or Stream to remove clean_sequence info from the loc

Returns:

new_tr_st (obspy.core.Trace or obspy.core.Trace)

static string(inp, out_format='minimal')

Returns the clean_sequence’s string representation

The form is “-” + id0 + “-” + id1 + …

By default, idx are minimized to contain the least characters uniquely identifying the seed id, from right to left

Parameters:

  • inp (:class:`obspy.core.Trace or `obspy.core.Stream) – Trace or Stream from which to get the clean_sequence(s)

  • out_format (str) – how to format the output: ‘minimal’: return the shortest string possible ‘min_code’: use the shortest string containing full codes ‘full’: return the full seedid string for each cleaned channel

Returns:

depending on whether you input Trace or Stream

Return type:

(str or list)

static tag(inp, clean_code, cleaned_ids=None, verbose=False)

Tag Trace stats with a clean_code

Parameters:

  • inp (Trace, Stream, list or None) – the object to tag

  • clean_code (str or list of str) – transformation code (‘ROT’, …) or the seed_id of the cleaned channel If a list, each str in the list will be appended

  • cleaned_ids (list) – a list of which Stream ids to apply to (can use wildcards). If None, applies to all of the Stream traces

Returns:

trace, stream, or list with modified clean_sequence

Return type:

outp (Trace, Stream, or list)

Raises:

  • ValueError if cleaned_ids is not None and trace_or_stream is a Trace –

  • TypeError if inp is not a Trace, Stream, list or NoneType –

static tiskitpy_id(seed_id, clean_sequence)

Returns a tiskitpy_id, based on a seed_id and a clean_sequence list

Parameters:

  • seed_id (str) – a valid seed_id (has three ‘.’s)

  • clean_sequence (list of str) – ordered list of cleaning steps: either seed_ids or transformation codes

Returns:

the tiskitpy_id

Return type:

(str)

tiskitpy.util_classes.SeisRotate

class tiskitpy.util_classes.SeisRotate(stream, uselogvar=False, max_reject_sync=0.01, H_over_Z=1.0, N_E_comps=('1', '2'))

Bases: object

Class to clean tilt noise from OBS vertical channel through non-deforming rotation

calc_zrotate_opt(lowcut=0.001, hicut=0.005, ignore_spans=None, uselogvar=None)

Calculate the Z channel rotation angle that minimizes tilt noise

Parameters:

  • lowcut (float) – low passband frequency in which to evaluate variance reduction

  • hicut (float) – high passpand frequency “” “” “”

  • ignore_spans (TimeSpans`) – time spans to ignore

  • uselogvar (bool) – use logarithmic variance estimate

Returns: (tuple)

angle (float): tilt angle (degrees, 0 means no tilt correction) azimuth (float): tilt azimuth (degrees) var_red (float): obtained reduction in variance (0 to 1)

The default (lowcut, hicut) values of (0.001, 0.005) correspond to the band where removing tilt noise generally has the greatest effect on the Z signal (at the low frequency end of the noise notch)

You can input the returned angles to rotateSeis.zrotate() to get the properly rotated data

copy()
Returns:

Copy of SeisRotate object.

Return type:

(SeisRotate)

plot()
static separate_streams(stream)

Separates input stream into seismometer and “other”

There must be one channel name ending in Z, one ending in N or 1 and one ending in E or 2

Parameters:

stream (Stream) – 3+ component data stream

Returns:

stream containt 3C seismometer channels other_stream (Stream): all other channels, or None

Return type:

seis_stream (Stream)

stream()

Return obspy 3-component stream()

zrotate(angle, azimuth, horiz_also=True)

Rotate a seismometer’s vertical component

Parameters:

  • angle (float) – angle towards vertical by which to rotate (degrees)

  • azimuth (float) – azimuth (CW from N) at which to rotate (degrees)

  • horiz_also (bool) – rotate horizontal components as well? (to retain orthogonality)

I would set horiz_also to:
False for the Guralp CMG-3T, which independently levels the three

components

True for the Trillium T240, which centers without rotation

(according to Dr Wieland)