def sigmoid(*columns):
"""Fit a Sigmoid through the data of the last scan.
The return value is a pair of tuples::
((a, b, x0, c), (d_a, d_b, d_x0, d_c))
where the elemets of the second tuple the estimated standard errors of the
fit parameters. The fit parameters are:
* a - amplitude of the Sigmoid
* b - steepness of the curve
* x0 - center
* c - background
if the fit failed, the result is ``(None, None)``.
Example::
cscan(...)
values, stderr = sigmoid('h', 'adet')
"""
xs, ys, dys, _, ds = _getData(columns)
fit = SigmoidFit()
res = fit.run(xs, ys, dys)
if res._failed:
return None, None
session.notifyFitCurve(ds, 'sigmoid', res.curve_x, res.curve_y)
descrs = ['amplitude', 'steepness', 'center', 'background']
vals = []
for par, err, descr in zip(res._pars[1], res._pars[2], descrs):
vals.append((descr, '%.4f' % par, '%.4f' % err))
printTable(('parameter', 'value', 'error'), vals, session.log.info)
return CommandLineFitResult((tuple(res._pars[1]), tuple(res._pars[2])))
def fit(fitclass, *columns, **kwargs):
xs, ys, dys, _, ds = _getData(columns, dataset=kwargs.pop('dataset', None))
fit = fitclass(**kwargs)
res = fit.run(xs, ys, dys)
if res._failed:
session.log.info('Fit failed.')
return CommandLineFitResult((None, None))
session.notifyFitCurve(ds, fit.fit_title, res.curve_x, res.curve_y)
descrs = fit.fit_p_descr
vals = []
for par, err, descr in zip(res._pars[1], res._pars[2], descrs):
vals.append((descr, '%.5g' % par, '+/- %.5g' % err,
'+/- {:.1%}'.format(err / par) if par else '-'))
printTable(('parameter', 'value', 'error', 'rel. error'), vals,
session.log.info)
return CommandLineFitResult((tuple(res._pars[1]), tuple(res._pars[2])))
def doStart(self):
positions = [[p] for p in self.positions]
ds = Scan([session.getDevice(self.scandev)],
positions,
None,
detlist=[self._attached_detector],
preset=self._preset,
subscan=True).run()
xs, ys, dys, _, ds = _getData()
fit = self.fitcls()
res = fit.run(xs, ys, dys)
if res._failed:
self.log.warning('Fit failed: %s.' % res._message)
self.readresult = [0] * (self._nparams * 2)
else:
session.notifyFitCurve(ds, fit.fit_title, res.curve_x, res.curve_y)
readres = []
for par, err in zip(res._pars[1], res._pars[2]):
readres.append(par)
readres.append(err)
self.readresult = readres