Base module

Overview

The shakelab.signals.base module provides functionality for basic waveform analysis.

ShakeLab provides three fundamental classes to manage and manipulate seismic waveform data: Record, Stream, and StreamCollection. These classes are designed to handle individual recordings, collections of non-contigous recordings from a single stream (e.g. from a single station and a specific channel), and collections of multiple streams, respectively.

Record Class

The Record class is the base element for seismic data management within ShakeLab. It represents a single continuous recording block, encapsulating both the waveform data and associated metadata, such as sampling rate, start time, and location.

It includes various methods for working with seismic signals, such as convolution, deconvolution, filtering, and various waveform analysis metrics.

Stream Class

The Stream class represents a collection of Record objects that belong to the same data stream, typically from the same seismic channel or station. The Stream class can handle both continuous and segmented data, managing gaps between Record objects if necessary.

A Stream object allows for operations that involve multiple Record objects, such as merging records, extracting specific time windows, and appending new data. Each Stream is associated with a single channel or station, but it may consist of multiple Record objects, especially if there are gaps in the data.

StreamCollection Class

The StreamCollection class represents a collection of Stream objects, essentially grouping multiple seismic channels or stations into a single collection. This class is useful for handling data from multiple sources simultaneously, allowing for operations across different streams.

The StreamCollection class acts as a container for multiple Stream objects, providing the ability to manage and process data from multiple seismic channels or stations collectively. Operations can be performed on the entire collection, such as merging streams or applying common processing steps across all contained streams.

Relationships Between Classes

  • A `StreamCollection` object contains multiple `Stream` objects, each corresponding to a different seismic channel or station.

  • Each `Stream` object contains a list of `Record` objects, representing different segments or time windows of data from the same channel or station.

  • `Record` is the foundational class, holding the actual waveform data and metadata. Multiple Record objects are grouped into a Stream, and multiple Stream objects are further grouped into a StreamCollection.

Example Usage

Here is a conceptual example of how these classes might be used together:

# Create a single Record
record1 = Record(data=[...], delta=0.01, time='2024-01-01T00:00:00', location=(45.0, 7.0), sid='STA1')

# Create another Record
record2 = Record(data=[...], delta=0.01, time='2024-01-01T00:01:00', location=(45.0, 7.0), sid='STA1')

# Create a Stream and add the Records
stream = Stream(id='STA1')
stream.append(record1)
stream.append(record2)

# Create a StreamCollection and add the Stream
stream_collection = StreamCollection()
stream_collection.append(stream)

# Accessing the first Record from the first Stream in the StreamCollection
first_record = stream_collection[0][0]

This setup allows for flexible and scalable management of seismic data, whether working with individual records, grouped streams, or entire collections of streams.

Python 
1from shakelab.signals.analysis import StreamCollection
2
3# Create a StreamCollection and read seismic data from a byte stream
4byte_stream = b"..."  # Actual byte stream content
5stream_collection = StreamCollection()
6stream_collection.read(byte_stream, ftype='mseed', byte_order='be')

Usage Examples

Creating a Record and Computing Spectrum

from shakelab.signals.analysis import Record

# Create a Record with sample data
time = Date(2023, 1, 1, 0, 0, 0)
data = np.random.rand(100)
record = Record(time=time, delta=0.01, data=data)

# Compute and plot the spectrum of the Record
spectrum = record.to_spectrum()
spectrum.plot()

Creating a Stream and Sorting Records

from shakelab.signals.analysis import Stream, Record

# Create a Stream with multiple Records
stream = Stream(sid='STATION1')
record1 = Record(time=Date(2023, 1, 1, 0, 0, 0), delta=0.01, data=np.random.rand(100))
record2 = Record(time=Date(2023, 1, 1, 0, 1, 0), delta=0.01, data=np.random.rand(100))
stream.append(record1)
stream.append(record2)

# Sort the records in the stream based on start times
stream.sort()

Creating a StreamCollection and Reading Data

from shakelab.signals.analysis import StreamCollection

# Create a StreamCollection and read seismic data from a byte stream
byte_stream = b"..."  # Actual byte stream content
stream_collection = StreamCollection()
stream_collection.read(byte_stream, ftype='mseed', byte_order='be')

These examples provide a glimpse of the functionality provided by the shakelab.signals.analysis module. Refer to the documentation for more details and advanced usage.