PSD class

pesummary handles PSD data through a custom PSD class. This PSD class is inherited from the numpy.ndarray class. Multiple PSDs are stored in the PSDDict class.

Initializing the PSD class

The PSD class is initialized with an 2d array containing the frequency and strain data,

>>> from pesummary.gw.file.psd import PSD
>>> import numpy as np
>>> frequencies = [0, 0.125, 0.25]
>>> strains = [0.25, 0.25, 0.25]
>>> psd_data = np.vstack([frequencies, strains]).T
>>> psd = PSD(psd_data)

Alternatively, a file containing the psd can be read in with,

>>> filename = "./IFO0_psd.dat"
>>> psd = PSD.read(filename)

Using the PSD object

The PSD object allows for you to save the stored PSD data with ease. This can be done with the following:

>>> psd.save_to_file("new_psd.dat", delimiter="\t")

Initializing the PSDDict class

The PSDDict class is initialized with a dictionary of 2d array’s containing the frequency and strain data for each detector you are interested in,

>>> from pesummary.gw.file.psd import PSDDict
>>> psd_data = {
...     "H1": [[0.00000e+00, 2.50000e-01],
...            [1.25000e-01, 2.50000e-01],
...            [2.50000e-01, 2.50000e-01]],
...     "V1": [[0.00000e+00, 2.50000e-01],
...            [1.25000e-01, 2.50000e-01],
...            [2.50000e-01, 2.50000e-01]]
... }
>>> psd_dict = PSDDict(psd_data)

The data for each detector is stored as a PSD object:

>>> type(psd_dict["H1"])
<class 'pesummary.gw.file.psd.PSD'>

If you have multiple psds stored in multiple files, you can simply run the following,

>>> psd_H1 = PSD.read("IFO0_psd.dat")
>>> psd_V1 = PSD.read("IFO2_psd.dat")
>>> psd_data = {"H1": psd_H1, "V1": psd_V1}
>>> psd_dict = PSDDict(psd_data)

Using the PSDDict object

The PSDDict object has extra helper functions and properties to make it easier for you to extract the information stored within. For example, you can list the detectors stored with,

>>> psd_dict.detectors
['H1', 'V1']

Or you can simply plot all stored PSDs on a single axis,

>>> psd_dict.plot()

The frequency and strain data for a specific IFO can also be extracted with,

>>> psd_dict["H1"].frequencies
array([0.   , 0.125, 0.25 ])
>>> psd_dict["H1"].strains
array([0.25, 0.25, 0.25])

pesummary.gw.file.psd.PSD

class pesummary.gw.file.psd.PSD(input_array)[source]

Class to handle PSD data

interpolate(low_freq_cutoff, delta_f)[source]

Interpolate PSD to a new delta_f

Parameters:

low_freq_cutoff (float) – Frequencies below this value are set to zero.
delta_f (float, optional) – Frequency resolution of the frequency series in Hertz.

classmethod read(path_to_file, **kwargs)[source]

Read in a file and initialize the PSD class

Parameters:

path_to_file (str) – the path to the file you wish to load
**kwargs (dict) – all kwargs are passed to the read methods

static read_from_dat(path_to_file, IFO=None, **kwargs)[source]

Read in a dat file and return a numpy array containing the data

Parameters:

path_to_file (str) – the path to the file you wish to load
**kwargs (dict) – all kwargs are passed to the numpy.genfromtxt method

static read_from_xml(path_to_file, IFO=None, **kwargs)[source]

Read in an xml file and return a numpy array containing the data

Parameters:

path_to_file (str) – the path to the file you wish to load
IFO (str, optional) – name of the dataset that you wish to load
**kwargs (dict) – all kwargs are passed to the gwpy.frequencyseries.FrequencySeries.read method

save_to_file(file_name, comments='#', delimiter='\t')[source]

Save the calibration data to file

Parameters:

file_name (str) – name of the file name that you wish to use
comments (str, optional) – String that will be prepended to the header and footer strings, to mark them as comments. Default is ‘#’.
delimiter (str, optional) – String or character separating columns.

to_pycbc(low_freq_cutoff, f_high=None, length=None, delta_f=None, f_high_override=False)[source]

Convert the PSD object to an interpolated pycbc.types.FrequencySeries

Parameters:

length (int, optional) – Length of the frequency series in samples.
delta_f (float, optional) – Frequency resolution of the frequency series in Herz.
low_freq_cutoff (float, optional) – Frequencies below this value are set to zero.
f_high_override (Bool, optional) – Override the final frequency if it is above the maximum stored. Default False

pesummary.gw.file.psd.PSDDict

class pesummary.gw.file.psd.PSDDict(*args)[source]

Class to handle a dictionary of PSDs

Parameters:

detectors (list) – list of detectors
data (nd list) – list of psd samples for each detector. First column is frequencies, second column is strains

detectors

list of detectors stored in the dictionary

Type:: list

plot:: Generate a plot based on the psd samples stored

to_pycbc:: Convert dictionary of PSD objects to a dictionary of pycbc.frequencyseries objects objects

Examples

>>> from pesummary.gw.file.psd import PSDDict
>>> detectors = ["H1", "V1"]
>>> psd_data = [
...     [[0.00000e+00, 2.50000e-01],
...      [1.25000e-01, 2.50000e-01],
...      [2.50000e-01, 2.50000e-01]],
...     [[0.00000e+00, 2.50000e-01],
...      [1.25000e-01, 2.50000e-01],
...      [2.50000e-01, 2.50000e-01]]
... ]
>>> psd_dict = PSDDict(detectors, psd_data)
>>> psd_data = {
...     "H1": [[0.00000e+00, 2.50000e-01],
...            [1.25000e-01, 2.50000e-01],
...            [2.50000e-01, 2.50000e-01]],
...     "V1": [[0.00000e+00, 2.50000e-01],
...            [1.25000e-01, 2.50000e-01],
...            [2.50000e-01, 2.50000e-01]]
... }
>>> psd_dict = PSDDict(psd_data)

interpolate(low_freq_cutoff, delta_f)[source]

Interpolate a dictionary of PSDs to a new delta_f

Parameters:

low_freq_cutoff (float) – Frequencies below this value are set to zero.
delta_f (float, optional) – Frequency resolution of the frequency series in Hertz.

plot(**kwargs)[source]

Generate a plot to display the PSD data stored in PSDDict

Parameters:: **kwargs (dict) – all additional kwargs are passed to pesummary.gw.plots.plot._psd_plot

classmethod read(files=None, detectors=None, common_string=None)[source]

Initiate PSDDict with a set of PSD files

Parameters:

files (list/dict, optional) – Either a list of files or a dictionary of files to read. If a list of files are provided, a list of corresponding detectors must also be provided
common_string (str, optional) – Common string for PSD files. The string must be formattable and take one argument which is the detector. For example common_string=’./{}_psd.dat’. Used if files is not provided
detectors (list, optional) – List of detectors to use when loading files. Used if files if not provided or if files is a list or if common_string is provided

to_pycbc(*args, **kwargs)[source]

Transform dictionary to pycbc.frequencyseries objects

Parameters:

*args (tuple) – all args passed to PSD.to_pycbc()
**kwargs (dict, optional) – all kwargs passed to PSD.to_pycbc()