pybaselines.spline.pspline_drpls

pybaselines.spline.pspline_drpls(data, lam=1000.0, eta=0.5, num_knots=100, spline_degree=3, diff_order=2, max_iter=50, tol=0.001, weights=None, x_data=None)[source]

A penalized spline version of the drPLS algorithm.

Parameters:

dataarray_like, shape (N,): The y-values of the measured data, with N data points. Must not contain missing data (NaN) or Inf.
lamfloat, optional: The smoothing parameter. Larger values will create smoother baselines. Default is 1e3.
etafloat: A term for controlling the value of lam; should be between 0 and 1. Low values will produce smoother baselines, while higher values will more aggressively fit peaks. Default is 0.5.
num_knotsint, optional: The number of knots for the spline. Default is 100.
spline_degreeint, optional: The degree of the spline. Default is 3, which is a cubic spline.
diff_orderint, optional: The order of the differential matrix. Must be greater than 0. Default is 2 (second order differential matrix). Typical values are 2 or 1.
max_iterint, optional: The max number of fit iterations. Default is 50.
tolfloat, optional: The exit criteria. Default is 1e-3.
weightsarray_like, shape (N,), optional: The weighting array. If None (default), then the initial weights will be an array with size equal to N and all values set to 1.
x_dataarray_like, shape (N,), optional: The x-values of the measured data. Default is None, which will create an array from -1 to 1 with N points.

Returns:

baselinenumpy.ndarray, shape (N,)

The calculated baseline.

paramsdict

A dictionary with the following items:

'weights': numpy.ndarray, shape (N,)
The weight array used for fitting the data.
'tol_history': numpy.ndarray
An array containing the calculated tolerance values for each iteration. The length of the array is the number of iterations completed. If the last value in the array is greater than the input tol value, then the function did not converge.

Raises:

ValueError: Raised if eta is not between 0 and 1 or if diff_order is less than 2.