# scipy.ndimage.spline_filter1d¶

scipy.ndimage.spline_filter1d(input, order=3, axis=-1, output=<class 'numpy.float64'>, mode='mirror')[source]

Calculate a one-dimensional spline filter along the given axis.

The lines of the array along the given axis are filtered by a spline filter. The order of the spline must be >= 2 and <= 5.

Parameters: input : array_like The input array. order : int, optional The order of the spline, default is 3. axis : int, optional The axis along which the spline filter is applied. Default is the last axis. output : ndarray or dtype, optional The array in which to place the output, or the dtype of the returned array. Default is numpy.float64. mode : {‘reflect’, ‘constant’, ‘nearest’, ‘mirror’, ‘wrap’}, optional The mode parameter determines how the input array is extended beyond its boundaries. Default is ‘constant’. Behavior for each valid value is as follows: ‘reflect’ (d c b a | a b c d | d c b a) The input is extended by reflecting about the edge of the last pixel. ‘constant’ (k k k k | a b c d | k k k k) The input is extended by filling all values beyond the edge with the same constant value, defined by the cval parameter. ‘nearest’ (a a a a | a b c d | d d d d) The input is extended by replicating the last pixel. ‘mirror’ (d c b | a b c d | c b a) The input is extended by reflecting about the center of the last pixel. ‘wrap’ (a b c d | a b c d | a b c d) The input is extended by wrapping around to the opposite edge. spline_filter1d : ndarray The filtered input.

Notes

All functions in ndimage.interpolation do spline interpolation of the input image. If using b-splines of order > 1, the input image values have to be converted to b-spline coefficients first, which is done by applying this one-dimensional filter sequentially along all axes of the input. All functions that require b-spline coefficients will automatically filter their inputs, a behavior controllable with the prefilter keyword argument. For functions that accept a mode parameter, the result will only be correct if it matches the mode used when filtering.

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