pyrfu.mms.vdf_omni#

pyrfu.mms.vdf_omni(vdf, method: str = 'mean')[source]#

Computes omni-directional distribution, without changing the units.

Parameters:

  • vdf (xarray.Dataset) –

    Time series of the 3D velocity distribution with :

    • time : Time samples.

    • data : 3D velocity distribution.

    • energy : Energy levels.

    • phi : Azimuthal angles.

    • theta : Elevation angle.

  • method ({"mean", "sum"}, Optional) – Method of computation. Use “sum” for counts and “mean” for everything else. Default is “mean”.

Returns:

out – Time series of the omnidirectional velocity distribution function: a DataArray (time, energy) with one energy table, or a Dataset with (time, energy) energies when the energy tables alternate. Both keep the units and the attributes of vdf (UNITS on the data variable of the Dataset, as for vdf).

Return type:

xarray.DataArray or xarray.Dataset

Raises:

ValueError – If method is not “mean” or “sum”.

Notes

As irfu-matlab PDist.omni, “mean” averages the distribution weighted by the solid angles over theta, then phi, and divides by the mean solid angle; without NaNs, this is the solid-angle weighted mean. A channel without data at all angles gives NaN (“mean”) or 0 (“sum”).