Time Series data

Gravitational-wave detectors are time-domain instruments, recording gravitational-wave amplitude as a differential change in the lengths of each of the interferometer arms. The primary output of these detectors is a single time-stream of gravitational-wave strain (also referred to as h(t)).

Alongside the strain data, thousands of instrumental control and error signals and environmental monitors are recorded in real-time and archived for off-line study. These data are colloquially called the auxiliary channels.

The TimeSeries

Importing the TimeSeries
from gwpy.timeseries import TimeSeries

GWpy provides the TimeSeries object as a way of representing time series data. The TimeSeries is built on top of the numpy.ndarray, and so many methods and applications of this object should be familiar to numpy users.

For example, to create a simple TimeSeries filled with random data:

Creating a TimeSeries with random data
>>> from numpy.random import random
>>> from gwpy.timeseries import TimeSeries
>>> t = TimeSeries(random(1000))
>>> print(t)
TimeSeries([ 0.59442285, 0.61979421, 0.62968915,...,  0.98309223,
             0.94513298, 0.1826175 ]
           unit: Unit(dimensionless),
           t0: 0.0 s,
           dt: 1.0 s,
           name: None,
           channel: None)

Here we see the random data we have created, as well as the associated metadata common to any time series data:

unit

The physical unit of these data

t0

X-axis coordinate of the first data point

dt

X-axis sample separation

name

Name for this data set

channel

Instrumental channel associated with these data

Associated classes

Alongside the TimeSeries class, gwpy.timeseries module provides a small set of related classes for handling collections of data:

TimeSeriesDict

Ordered key-value mapping of named TimeSeries objects

TimeSeriesList

Fancy list representing a list of TimeSeries

Reading/writing time series data

Plotting time series data

Reference/API

The above documentation references the following objects:

TimeSeries

A time-domain data array.

TimeSeriesDict

Ordered key-value mapping of named TimeSeries objects

TimeSeriesList

Fancy list representing a list of TimeSeries