"""Utilities for working with data and models."""
from itertools import repeat
from functools import partial
import numpy as np
from fooof.core.modutils import docs_get_section, replace_docstring_sections
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[docs]def trim_spectrum(freqs, power_spectra, f_range):
"""Extract a frequency range from power spectra.
Parameters
----------
freqs : 1d array
Frequency values for the power spectrum.
power_spectra : 1d or 2d array
Power spectral density values.
f_range: list of [float, float]
Frequency range to restrict to, as [lowest_freq, highest_freq].
Returns
-------
freqs_ext : 1d array
Extracted frequency values for the power spectrum.
power_spectra_ext : 1d or 2d array
Extracted power spectral density values.
Notes
-----
This function extracts frequency ranges >= f_low and <= f_high.
It does not round to below or above f_low and f_high, respectively.
Examples
--------
Using a simulated spectrum, extract a frequency range:
>>> from fooof.sim import gen_power_spectrum
>>> freqs, powers = gen_power_spectrum([1, 50], [1, 1], [10, 0.5, 1.0])
>>> freqs, powers = trim_spectrum(freqs, powers, [3, 30])
"""
# Create mask to index only requested frequencies
f_mask = np.logical_and(freqs >= f_range[0], freqs <= f_range[1])
# Restrict freqs & spectra to requested range
# The if/else is to cover both 1d or 2d arrays
freqs_ext = freqs[f_mask]
power_spectra_ext = power_spectra[f_mask] if power_spectra.ndim == 1 \
else power_spectra[:, f_mask]
return freqs_ext, power_spectra_ext
[docs]def interpolate_spectrum(freqs, powers, interp_range, buffer=3):
"""Interpolate a frequency region in a power spectrum.
Parameters
----------
freqs : 1d array
Frequency values for the power spectrum.
powers : 1d array
Power values for the power spectrum.
interp_range : list of float or list of list of float
Frequency range to interpolate, as [lowest_freq, highest_freq].
If a list of lists, applies each as it's own interpolation range.
buffer : int or list of int
The number of samples to use on either side of the interpolation
range, that are then averaged and used to calculate the interpolation.
Returns
-------
freqs : 1d array
Frequency values for the power spectrum.
powers : 1d array
Power values, with interpolation, for the power spectrum.
Notes
-----
This function takes in, and returns, linearly spaced values.
This approach interpolates data linearly, in log-log spacing. This assumes a
1/f property of the data, and so should only be applied where this assumption
is valid. This approach is intended for interpolating small frequency ranges,
such as line noise regions.
The interpolation range is taken as the range from >= interp_range_low and
<= interp_range_high. It does not round to below or above interp_range_low
and interp_range_high, respectively.
To be more robust to noise, this approach takes a number of samples on either
side of the interpolation range (the number of which is controlled by `buffer`)
and averages these points to linearly interpolate between them.
Setting `buffer=1` is equivalent to a linear interpolation between
the points adjacent to the interpolation range.
Examples
--------
Using a simulated spectrum, interpolate away a line noise peak:
>>> from fooof.sim import gen_power_spectrum
>>> freqs, powers = gen_power_spectrum([1, 75], [1, 1], [[10, 0.5, 1.0], [60, 2, 0.1]])
>>> freqs, powers = interpolate_spectrum(freqs, powers, [58, 62])
"""
# If given a list of interpolation zones, recurse to apply each one
if isinstance(interp_range[0], list):
buffer = repeat(buffer) if isinstance(buffer, int) else buffer
for interp_zone, cur_buffer in zip(interp_range, buffer):
freqs, powers = interpolate_spectrum(freqs, powers, interp_zone, cur_buffer)
# Assuming list of two floats, interpolate a single frequency range
else:
# Take a copy of the array, to not change original array
powers = np.copy(powers)
# Get the set of frequency values that need to be interpolated
interp_mask = np.logical_and(freqs >= interp_range[0], freqs <= interp_range[1])
interp_freqs = freqs[interp_mask]
# Get the indices of the interpolation range
ii1, ii2 = np.flatnonzero(interp_mask)[[0, -1]]
# Extract & log the requested range of data to use around interpolated range
xs1 = np.log10(freqs[ii1-buffer:ii1])
xs2 = np.log10(freqs[ii2:ii2+buffer])
ys1 = np.log10(powers[ii1-buffer:ii1])
ys2 = np.log10(powers[ii2:ii2+buffer])
# Linearly interpolate, in log-log space, between averages of the extracted points
vals = np.interp(np.log10(interp_freqs),
[np.median(xs1), np.median(xs2)],
[np.median(ys1), np.median(ys2)])
powers[interp_mask] = np.power(10, vals)
return freqs, powers
def wrap_interpolate_spectrum(powers, freqs, interp_range, buffer):
"""Wraps interpolate function, organizing inputs & outputs to use `partial`."""
return interpolate_spectrum(freqs, powers, interp_range, buffer)[1]
[docs]@replace_docstring_sections(docs_get_section(interpolate_spectrum.__doc__, 'Notes', end='Examples'))
def interpolate_spectra(freqs, powers, interp_range, buffer=3):
"""Interpolate a frequency region across a group of power spectra.
Parameters
----------
freqs : 1d array
Frequency values for the power spectrum.
powers : 2d array
Power values for the power spectra.
interp_range : list of float or list of list of float
Frequency range to interpolate, as [lowest_freq, highest_freq].
If a list of lists, applies each as it's own interpolation range.
buffer : int or list of int
The number of samples to use on either side of the interpolation
range, that are then averaged and used to calculate the interpolation.
Returns
-------
freqs : 1d array
Frequency values for the power spectrum.
powers : 2d array
Power values, with interpolation, for the power spectra.
Notes
-----
% copied in from interpolate_spectrum
Examples
--------
Using simulated spectra, interpolate away line noise peaks:
>>> from fooof.sim import gen_group_power_spectra
>>> freqs, powers = gen_group_power_spectra(5, [1, 75], [1, 1], [[10, 0.5, 1.0], [60, 2, 0.1]])
>>> freqs, powers = interpolate_spectra(freqs, powers, [58, 62])
"""
tfunc = partial(wrap_interpolate_spectrum, freqs=freqs,
interp_range=interp_range, buffer=buffer)
powers = np.apply_along_axis(tfunc, 1, powers)
return freqs,powers
[docs]def subsample_spectra(spectra, selection, return_inds=False):
"""Subsample a group of power spectra.
Parameters
----------
spectra : 2d array
A group of power spectra to subsample from.
selection : int or float
The number of spectra to subsample.
If int, is the number to select, if float, is a proportion based on input size.
return_inds : bool, optional, default: False
Whether to return the list of indices that were selected.
Returns
-------
subsample : 2d array
A subsampled selection of power spectra.
inds : list of int
A list of which indices where subsampled.
Only returned if `return_inds` is True.
Examples
--------
Using a group of simulated spectra, subsample a specific number:
>>> from fooof.sim import gen_group_power_spectra
>>> freqs, powers = gen_group_power_spectra(10, [1, 50], [1, 1], [10, 0.5, 1.0])
>>> subsample = subsample_spectra(powers, 5)
Using a group of simulated spectra, subsample a proportion:
>>> from fooof.sim import gen_group_power_spectra
>>> freqs, powers = gen_group_power_spectra(10, [1, 50], [1, 1], [10, 0.5, 1.0])
>>> subsample = subsample_spectra(powers, 0.25)
"""
n_spectra = spectra.shape[0]
if isinstance(selection, float):
n_sample = int(n_spectra * selection)
else:
n_sample = selection
inds = np.random.choice(n_spectra, n_sample, replace=False)
subsample = spectra[inds, :]
if return_inds:
return subsample, inds
else:
return subsample