ozzy.fields

This submodule includes functions to analyze field data.

vphi_from_fit

vphi_from_fit(
    da,
    x_zero,
    xvar="x1",
    tvar="t",
    window_len=1.0,
    k=1.0,
    boundary="trim",
    quasistatic_fixed_z=False,
)

Measure the phase (\(\phi\)) and phase velocity (\(v_\phi\)) from stacked lineouts of a wave (waterfall data) by fitting a sinusoidal function to blocks of data.

Parameters:

Name	Type	Description	Default
da	DataArray	The input xarray.DataArray containing the data to be analyzed. The data should be two-dimensional: time or propagation distance along one dimension, and a longitudinal coordinate along the other dimension.	required
x_zero	float	Position along the longitudinal coordinate where the sine should be considered to start, and with respect to which the phase will be measured. For example, a seed position.	required
xvar	str	The name of the spatial dimension along which to perform the fit. Default is 'x1'.	'x1'
tvar	str	The name of the time or propagation dimension. Default is 't'.	't'
window_len	float	The length of the window (in units of the plasma wavelength) over which to perform the fit. Default is 1.0.	1.0
k	float | str	The wavenumber to use in the definition of the window length. If 'fft', the wavenumber will be calculated from the FFT of the data. Default is 1.0.	1.0
boundary	str	How to handle boundaries when coarsening the data into blocks. One of 'trim', 'pad', or 'drop'. See xarray.DataArray.coarsen.	'trim'
quasistatic_fixed_z	bool	If True, the phase velocity is calculated assuming a quasistatic approximation with a fixed z-dimension. Default is False.	False

Returns:

Type	Description
Dataset	A dataset containing the calculated phase velocity ('vphi'), phase ('phi'), and phase error ('phi_err').