spinguin.core.specutils

spinguin.core.specutils#

This module provides core functions for spectral data analysis, including Fourier transforms, spectrum generation, and unit conversions commonly used in NMR and signal processing.

fourier_transform(signal: ndarray, dt: float, normalize: bool = True) → tuple[ndarray, ndarray][source]#

Computes the Fourier transform of a given time-domain signal and returns the corresponding frequency-domain representation. The Fourier transform can be normalized to ensure consistent peak intensities regardless of the time step.

Parameters:

  • signal (ndarray) – Input signal in the time domain.

  • dt (float) – Time step between consecutive samples in the signal.

  • normalize (bool, default=True) – Whether to normalize the Fourier transform.

Returns:

  • freqs (ndarray) – Frequencies corresponding to the Fourier-transformed signal.

  • fft_signal (ndarray) – Fourier-transformed signal in the frequency domain (normalized if specified).

frequency_to_chemical_shift(frequency: float | ndarray, reference_frequency: float, spectrometer_frequency: float) → float | ndarray[source]#

Converts a frequency (or an array of frequencies, e.g., a frequency axis) to a chemical shift value based on the reference frequency and the spectrometer frequency.

Parameters:

  • frequency (float or ndarray) – Frequency (or array of frequencies) to convert [in Hz].

  • reference_frequency (float) – Reference frequency for the conversion [in Hz].

  • spectrometer_frequency (float) – Spectrometer frequency for the conversion [in Hz].

Returns:

chemical_shift – Converted chemical shift value (or array of values).

Return type:

float or ndarray

resonance_frequency(isotope: str, B: float, delta: float = 0, unit: Literal['Hz', 'rad/s'] = 'Hz') → float[source]#

Computes the resonance frequency of a nucleus at specified magnetic field and chemical shift.

Parameters:

  • isotope (str) – Nucleus symbol (e.g. ‘1H’) used to select the gyromagnetic ratio.

  • B (float) – Magnetic field strength in the units of T.

  • delta (float, default=0) – Chemical shift in ppm.

  • unit ({'Hz', 'rad/s'}) – Specifies in which units the frequency is returned.

Returns:

omega – Resonance frequency of the given nucleus.

Return type:

float

spectral_width_to_dwell_time(spectral_width: float, isotope: str, B: float) → float[source]#

Calculates the dwell time (in seconds) from the spectral width given in ppm.

Parameters:

  • spectral_width (float) – Spectral width in ppm.

  • isotope (str) – Nucleus symbol (e.g. ‘1H’) used to select the gyromagnetic ratio required for the conversion.

  • B (float) – Magnetic field of the spectrometer in T.

Returns:

dwell_time – Dwell time in seconds.

Return type:

float

spectrum(signal: ndarray, dt: float, normalize: bool = True, part: Literal['real', 'imag'] = 'real') → tuple[ndarray, ndarray][source]#

A wrapper function for the Fourier transform. Computes the Fourier transform and returns the frequency and spectrum (either the real or imaginary part of the Fourier transform).

Parameters:

  • signal (ndarray) – Input signal in the time domain.

  • dt (float) – Time step between consecutive samples in the signal.

  • normalize (bool, default=True) – Whether to normalize the Fourier transform.

  • part ({'real', 'imag'}) – Specifies which part of the Fourier transform to return. Can be “real” or “imag”.

Returns:

  • freqs (ndarray) – Frequencies corresponding to the Fourier-transformed signal.

  • spectrum (ndarray) – Specified part (real or imaginary) of the Fourier-transformed signal in the frequency domain.

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