PlasmaCalcs.tools.xarray_tools.xarray_sci.XarrayCurveFitter

class PlasmaCalcs.tools.xarray_tools.xarray_sci.XarrayCurveFitter(array, dim, *, promote_dims_if_needed=True, pnames=UNSET, pbounds=UNSET, bounds=UNSET, **kw_curve_fit)

Bases: object

class for helping with curve fitting.

Not intended for direct use; subclass must define f:

f: function to fit. callable like f(x, param1, param2, …)

array: xarray.DataArray

array to use for fitting.

dim: str

dim to fit along.

promote_dims_if_needed: bool

whether to promote non-dimension coords to dimensions.

if False, raise DimensionKeyError if any relevant coord is not already a dimension.

pnames: UNSET, None, or list of str

names of params. If provided, ‘param’ coord will be assigned these names.

UNSET –> use cls.pnames (default: None)

None –> no pnames provided

pbounds: UNSET, or list of [None, callable, or 2-tuple of value, None, or callable]

bounds for each parameter. Provide pbounds or bounds, but not both.

UNSET –> use cls.pbounds (default: None)

None –> no pbounds provided

Each bound can be:

callable –> call as bound(array) (after doing array.pc.ensure_dims(dim)).

None –> use (-np.inf, np.inf).

2-tuple –> (lower, upper).

callable –> use lower(array) / upper(array)

None –> use -np.inf / np.inf.

bounds: UNSET or (list of lower bounds, list of upper bounds)

bounds, formatted as expected by scipy curve_fit.

Provide pbounds or bounds, but not both.

additional kwargs go to scipy.optimize.curve_fit.

__init__(array, dim, *, promote_dims_if_needed=True, pnames=UNSET, pbounds=UNSET, bounds=UNSET, **kw_curve_fit)

Methods

__init__(array, dim, *[, ...])
eval([xdata, params])
f(x, *params)
fit(*[, stddev])

Attributes

fitted
params
pbounds
pnames
xdata

eval(xdata=UNSET, params=UNSET)

evaluate curve fit result (params) at these xdata.

Equivalent: xarray_curve_eval(params, self.f, xdata)

xdata: UNSET or 1D xarray.DataArray

x values at which to evaluate the fit.

UNSET –> use self.xdata.

params: UNSET or values of params from a fit.

UNSET –> use self.params

[EFF] note: if self.f is well-vectorized, it is equivalent and faster to do:

self.f(xdata, *params.transpose(‘param’, …))

f(x, *params)

function to fit. callable like f(x, param1, param2, …).

[Not implemented here; subclass should implement]

fit(*, stddev=UNSET)

curve_fit to ydata = self.array, xdata = self.array[self.dim].

Remembers result in self.fitted. Returns self.fitted.

stddev: UNSET or bool

whether to include data_var ‘stddev’ telling standard deviation of the fit.

UNSET –> use value from self.kw_curve_fit, else default of xarray_curve_fit.

property fitted

result of latest call to self.fit().

None if never called self.fit(), or if crashed before finishing self.fit().

property params

alias to self.fitted[‘params’], the params from latest call to self.fit.

crash with helpful message if self.fitted doesn’t exist.

property xdata

alias to self.array[self.dim]