Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

1155 lines (1039 sloc) 40.632 kb
# Copyright (C) 2003-2005 Peter J. Verveer
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
#
# 3. The name of the author may not be used to endorse or promote
# products derived from this software without specific prior
# written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
# GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import math
import numpy
import _ni_support
import _nd_image
from scipy.misc import doccer
__all__ = ['correlate1d', 'convolve1d', 'gaussian_filter1d', 'gaussian_filter',
'prewitt', 'sobel', 'generic_laplace', 'laplace',
'gaussian_laplace', 'generic_gradient_magnitude',
'gaussian_gradient_magnitude', 'correlate', 'convolve',
'uniform_filter1d', 'uniform_filter', 'minimum_filter1d',
'maximum_filter1d', 'minimum_filter', 'maximum_filter',
'rank_filter', 'median_filter', 'percentile_filter',
'generic_filter1d', 'generic_filter']
_input_doc = \
"""input : array-like
input array to filter"""
_axis_doc = \
"""axis : integer, optional
axis of ``input`` along which to calculate. Default is -1"""
_output_doc = \
"""output : array, optional
The ``output`` parameter passes an array in which to store the
filter output."""
_size_foot_doc = \
"""size : scalar or tuple, optional
See footprint, below
footprint : array, optional
Either ``size`` or ``footprint`` must be defined. ``size`` gives
the shape that is taken from the input array, at every element
position, to define the input to the filter function.
``footprint`` is a boolean array that specifies (implicitly) a
shape, but also which of the elements within this shape will get
passed to the filter function. Thus ``size=(n,m)`` is equivalent
to ``footprint=np.ones((n,m))``. We adjust ``size`` to the number
of dimensions of the input array, so that, if the input array is
shape (10,10,10), and ``size`` is 2, then the actual size used is
(2,2,2).
"""
_mode_doc = \
"""mode : {'reflect','constant','nearest','mirror', 'wrap'}, optional
The ``mode`` parameter determines how the array borders are
handled, where ``cval`` is the value when mode is equal to
'constant'. Default is 'reflect'"""
_cval_doc = \
"""cval : scalar, optional
Value to fill past edges of input if ``mode`` is 'constant'. Default
is 0.0"""
_origin_doc = \
"""origin : scalar, optional
The ``origin`` parameter controls the placement of the filter. Default 0"""
_extra_arguments_doc = \
"""extra_arguments : sequence, optional
Sequence of extra positional arguments to pass to passed function"""
_extra_keywords_doc = \
"""extra_keywords : dict, optional
dict of extra keyword arguments to pass to passed function"""
docdict = {
'input':_input_doc,
'axis':_axis_doc,
'output':_output_doc,
'size_foot':_size_foot_doc,
'mode':_mode_doc,
'cval':_cval_doc,
'origin':_origin_doc,
'extra_arguments':_extra_arguments_doc,
'extra_keywords':_extra_keywords_doc,
}
docfiller = doccer.filldoc(docdict)
@docfiller
def correlate1d(input, weights, axis = -1, output = None, mode = "reflect",
cval = 0.0, origin = 0):
"""Calculate a one-dimensional correlation along the given axis.
The lines of the array along the given axis are correlated with the
given weights.
Parameters
----------
%(input)s
weights : array
one-dimensional sequence of numbers
%(axis)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
output, return_value = _ni_support._get_output(output, input)
weights = numpy.asarray(weights, dtype=numpy.float64)
if weights.ndim != 1 or weights.shape[0] < 1:
raise RuntimeError('no filter weights given')
if not weights.flags.contiguous:
weights = weights.copy()
axis = _ni_support._check_axis(axis, input.ndim)
if ((len(weights) // 2 + origin < 0) or
(len(weights) // 2 + origin > len(weights))):
raise ValueError('invalid origin')
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.correlate1d(input, weights, axis, output, mode, cval,
origin)
return return_value
@docfiller
def convolve1d(input, weights, axis = -1, output = None, mode = "reflect",
cval = 0.0, origin = 0):
"""Calculate a one-dimensional convolution along the given axis.
The lines of the array along the given axis are convolved with the
given weights.
Parameters
----------
%(input)s
weights : ndarray
one-dimensional sequence of numbers
%(axis)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
weights = weights[::-1]
origin = -origin
if not len(weights) & 1:
origin -= 1
return correlate1d(input, weights, axis, output, mode, cval, origin)
@docfiller
def gaussian_filter1d(input, sigma, axis = -1, order = 0, output = None,
mode = "reflect", cval = 0.0, truncate = 4.0):
"""One-dimensional Gaussian filter.
Parameters
----------
%(input)s
sigma : scalar
standard deviation for Gaussian kernel
%(axis)s
order : {0, 1, 2, 3}, optional
An order of 0 corresponds to convolution with a Gaussian
kernel. An order of 1, 2, or 3 corresponds to convolution with
the first, second or third derivatives of a Gaussian. Higher
order derivatives are not implemented
%(output)s
%(mode)s
%(cval)s
truncate : float
Truncate the filter at this many standard deviations.
Default is 4.0.
"""
if order not in range(4):
raise ValueError('Order outside 0..3 not implemented')
sd = float(sigma)
# make the radius of the filter equal to truncate standard deviations
lw = int(truncate * sd + 0.5)
weights = [0.0] * (2 * lw + 1)
weights[lw] = 1.0
sum = 1.0
sd = sd * sd
# calculate the kernel:
for ii in range(1, lw + 1):
tmp = math.exp(-0.5 * float(ii * ii) / sd)
weights[lw + ii] = tmp
weights[lw - ii] = tmp
sum += 2.0 * tmp
for ii in range(2 * lw + 1):
weights[ii] /= sum
# implement first, second and third order derivatives:
if order == 1 : # first derivative
weights[lw] = 0.0
for ii in range(1, lw + 1):
x = float(ii)
tmp = -x / sd * weights[lw + ii]
weights[lw + ii] = -tmp
weights[lw - ii] = tmp
elif order == 2: # second derivative
weights[lw] *= -1.0 / sd
for ii in range(1, lw + 1):
x = float(ii)
tmp = (x * x / sd - 1.0) * weights[lw + ii] / sd
weights[lw + ii] = tmp
weights[lw - ii] = tmp
elif order == 3: # third derivative
weights[lw] = 0.0
sd2 = sd * sd
for ii in range(1, lw + 1):
x = float(ii)
tmp = (3.0 - x * x / sd) * x * weights[lw + ii] / sd2
weights[lw + ii] = -tmp
weights[lw - ii] = tmp
return correlate1d(input, weights, axis, output, mode, cval, 0)
@docfiller
def gaussian_filter(input, sigma, order = 0, output = None,
mode = "reflect", cval = 0.0, truncate = 4.0):
"""Multi-dimensional Gaussian filter.
Parameters
----------
%(input)s
sigma : scalar or sequence of scalars
standard deviation for Gaussian kernel. The standard
deviations of the Gaussian filter are given for each axis as a
sequence, or as a single number, in which case it is equal for
all axes.
order : {0, 1, 2, 3} or sequence from same set, optional
The order of the filter along each axis is given as a sequence
of integers, or as a single number. An order of 0 corresponds
to convolution with a Gaussian kernel. An order of 1, 2, or 3
corresponds to convolution with the first, second or third
derivatives of a Gaussian. Higher order derivatives are not
implemented
%(output)s
%(mode)s
%(cval)s
truncate : float
Truncate the filter at this many standard deviations.
Default is 4.0.
Notes
-----
The multi-dimensional filter is implemented as a sequence of
one-dimensional convolution filters. The intermediate arrays are
stored in the same data type as the output. Therefore, for output
types with a limited precision, the results may be imprecise
because intermediate results may be stored with insufficient
precision.
"""
input = numpy.asarray(input)
output, return_value = _ni_support._get_output(output, input)
orders = _ni_support._normalize_sequence(order, input.ndim)
if not set(orders).issubset(set(range(4))):
raise ValueError('Order outside 0..4 not implemented')
sigmas = _ni_support._normalize_sequence(sigma, input.ndim)
axes = range(input.ndim)
axes = [(axes[ii], sigmas[ii], orders[ii])
for ii in range(len(axes)) if sigmas[ii] > 1e-15]
if len(axes) > 0:
for axis, sigma, order in axes:
gaussian_filter1d(input, sigma, axis, order, output,
mode, cval, truncate)
input = output
else:
output[...] = input[...]
return return_value
@docfiller
def prewitt(input, axis = -1, output = None, mode = "reflect", cval = 0.0):
"""Calculate a Prewitt filter.
Parameters
----------
%(input)s
%(axis)s
%(output)s
%(mode)s
%(cval)s
"""
input = numpy.asarray(input)
axis = _ni_support._check_axis(axis, input.ndim)
output, return_value = _ni_support._get_output(output, input)
correlate1d(input, [-1, 0, 1], axis, output, mode, cval, 0)
axes = [ii for ii in range(input.ndim) if ii != axis]
for ii in axes:
correlate1d(output, [1, 1, 1], ii, output, mode, cval, 0,)
return return_value
@docfiller
def sobel(input, axis = -1, output = None, mode = "reflect", cval = 0.0):
"""Calculate a Sobel filter.
Parameters
----------
%(input)s
%(axis)s
%(output)s
%(mode)s
%(cval)s
"""
input = numpy.asarray(input)
axis = _ni_support._check_axis(axis, input.ndim)
output, return_value = _ni_support._get_output(output, input)
correlate1d(input, [-1, 0, 1], axis, output, mode, cval, 0)
axes = [ii for ii in range(input.ndim) if ii != axis]
for ii in axes:
correlate1d(output, [1, 2, 1], ii, output, mode, cval, 0)
return return_value
@docfiller
def generic_laplace(input, derivative2, output = None, mode = "reflect",
cval = 0.0,
extra_arguments = (),
extra_keywords = None):
"""Calculate a multidimensional laplace filter using the provided
second derivative function.
Parameters
----------
%(input)s
derivative2 : callable
Callable with the following signature::
derivative2(input, axis, output, mode, cval,
*extra_arguments, **extra_keywords)
See `extra_arguments`, `extra_keywords` below.
%(output)s
%(mode)s
%(cval)s
%(extra_keywords)s
%(extra_arguments)s
"""
if extra_keywords is None:
extra_keywords = {}
input = numpy.asarray(input)
output, return_value = _ni_support._get_output(output, input)
axes = range(input.ndim)
if len(axes) > 0:
derivative2(input, axes[0], output, mode, cval,
*extra_arguments, **extra_keywords)
for ii in range(1, len(axes)):
tmp = derivative2(input, axes[ii], output.dtype, mode, cval,
*extra_arguments, **extra_keywords)
output += tmp
else:
output[...] = input[...]
return return_value
@docfiller
def laplace(input, output = None, mode = "reflect", cval = 0.0):
"""Calculate a multidimensional laplace filter using an estimation
for the second derivative based on differences.
Parameters
----------
%(input)s
%(output)s
%(mode)s
%(cval)s
"""
def derivative2(input, axis, output, mode, cval):
return correlate1d(input, [1, -2, 1], axis, output, mode, cval, 0)
return generic_laplace(input, derivative2, output, mode, cval)
@docfiller
def gaussian_laplace(input, sigma, output = None, mode = "reflect",
cval = 0.0, **kwargs):
"""Calculate a multidimensional laplace filter using gaussian
second derivatives.
Parameters
----------
%(input)s
sigma : scalar or sequence of scalars
The standard deviations of the Gaussian filter are given for
each axis as a sequence, or as a single number, in which case
it is equal for all axes..
%(output)s
%(mode)s
%(cval)s
Extra keyword arguments will be passed to gaussian_filter().
"""
input = numpy.asarray(input)
def derivative2(input, axis, output, mode, cval, sigma, **kwargs):
order = [0] * input.ndim
order[axis] = 2
return gaussian_filter(input, sigma, order, output, mode, cval,
**kwargs)
return generic_laplace(input, derivative2, output, mode, cval,
extra_arguments = (sigma,),
extra_keywords = kwargs)
@docfiller
def generic_gradient_magnitude(input, derivative, output = None,
mode = "reflect", cval = 0.0,
extra_arguments = (), extra_keywords = None):
"""Calculate a gradient magnitude using the provided function for
the gradient.
Parameters
----------
%(input)s
derivative : callable
Callable with the following signature::
derivative(input, axis, output, mode, cval,
*extra_arguments, **extra_keywords)
See `extra_arguments`, `extra_keywords` below.
`derivative` can assume that `input` and `output` are ndarrays.
Note that the output from `derivative` is modified inplace;
be careful to copy important inputs before returning them.
%(output)s
%(mode)s
%(cval)s
%(extra_keywords)s
%(extra_arguments)s
"""
if extra_keywords is None:
extra_keywords = {}
input = numpy.asarray(input)
output, return_value = _ni_support._get_output(output, input)
axes = range(input.ndim)
if len(axes) > 0:
derivative(input, axes[0], output, mode, cval,
*extra_arguments, **extra_keywords)
numpy.multiply(output, output, output)
for ii in range(1, len(axes)):
tmp = derivative(input, axes[ii], output.dtype, mode, cval,
*extra_arguments, **extra_keywords)
numpy.multiply(tmp, tmp, tmp)
output += tmp
# This allows the sqrt to work with a different default casting
if numpy.version.short_version > '1.6.1':
numpy.sqrt(output, output, casting='unsafe')
else:
numpy.sqrt(output, output)
else:
output[...] = input[...]
return return_value
@docfiller
def gaussian_gradient_magnitude(input, sigma, output = None,
mode = "reflect", cval = 0.0, **kwargs):
"""Calculate a multidimensional gradient magnitude using gaussian
derivatives.
Parameters
----------
%(input)s
sigma : scalar or sequence of scalars
The standard deviations of the Gaussian filter are given for
each axis as a sequence, or as a single number, in which case
it is equal for all axes..
%(output)s
%(mode)s
%(cval)s
Extra keyword arguments will be passed to gaussian_filter().
"""
input = numpy.asarray(input)
def derivative(input, axis, output, mode, cval, sigma, **kwargs):
order = [0] * input.ndim
order[axis] = 1
return gaussian_filter(input, sigma, order, output, mode,
cval, **kwargs)
return generic_gradient_magnitude(input, derivative, output, mode,
cval, extra_arguments = (sigma,),
extra_keywords = kwargs)
def _correlate_or_convolve(input, weights, output, mode, cval, origin,
convolution):
input = numpy.asarray(input)
if numpy.iscomplexobj(int):
raise TypeError('Complex type not supported')
origins = _ni_support._normalize_sequence(origin, input.ndim)
weights = numpy.asarray(weights, dtype=numpy.float64)
wshape = [ii for ii in weights.shape if ii > 0]
if len(wshape) != input.ndim:
raise RuntimeError('filter weights array has incorrect shape.')
if convolution:
weights = weights[tuple([slice(None, None, -1)] * weights.ndim)]
for ii in range(len(origins)):
origins[ii] = -origins[ii]
if not weights.shape[ii] & 1:
origins[ii] -= 1
for origin, lenw in zip(origins, wshape):
if (lenw // 2 + origin < 0) or (lenw // 2 + origin > lenw):
raise ValueError('invalid origin')
if not weights.flags.contiguous:
weights = weights.copy()
output, return_value = _ni_support._get_output(output, input)
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.correlate(input, weights, output, mode, cval, origins)
return return_value
@docfiller
def correlate(input, weights, output = None, mode = 'reflect', cval = 0.0,
origin = 0):
"""
Multi-dimensional correlation.
The array is correlated with the given kernel.
Parameters
----------
input : array-like
input array to filter
weights : ndarray
array of weights, same number of dimensions as input
output : array, optional
The ``output`` parameter passes an array in which to store the
filter output.
mode : {'reflect','constant','nearest','mirror', 'wrap'}, optional
The ``mode`` parameter determines how the array borders are
handled, where ``cval`` is the value when mode is equal to
'constant'. Default is 'reflect'
cval : scalar, optional
Value to fill past edges of input if ``mode`` is 'constant'. Default
is 0.0
origin : scalar, optional
The ``origin`` parameter controls the placement of the filter.
Default 0
See Also
--------
convolve : Convolve an image with a kernel.
"""
return _correlate_or_convolve(input, weights, output, mode, cval,
origin, False)
@docfiller
def convolve(input, weights, output = None, mode = 'reflect', cval = 0.0,
origin = 0):
"""
Multi-dimensional convolution.
The array is convolved with the given kernel.
Parameters
----------
input : array_like
Input array to filter.
weights : array_like
Array of weights, same number of dimensions as input
output : ndarray, optional
The `output` parameter passes an array in which to store the
filter output.
mode : {'reflect','constant','nearest','mirror', 'wrap'}, optional
the `mode` parameter determines how the array borders are
handled. For 'constant' mode, values beyond borders are set to be
`cval`. Default is 'reflect'.
cval : scalar, optional
Value to fill past edges of input if `mode` is 'constant'. Default
is 0.0
origin : scalar, optional
The `origin` parameter controls the placement of the filter.
Default is 0.
Returns
-------
result : ndarray
The result of convolution of `input` with `weights`.
See Also
--------
correlate : Correlate an image with a kernel.
Notes
-----
Each value in result is :math:`C_i = \\sum_j{I_{i+j-k} W_j}`, where
W is the `weights` kernel,
j is the n-D spatial index over :math:`W`,
I is the `input` and k is the coordinate of the center of
W, specified by `origin` in the input parameters.
Examples
--------
Perhaps the simplest case to understand is ``mode='constant', cval=0.0``,
because in this case borders (i.e. where the `weights` kernel, centered
on any one value, extends beyond an edge of `input`.
>>> a = np.array([[1, 2, 0, 0],
.... [5, 3, 0, 4],
.... [0, 0, 0, 7],
.... [9, 3, 0, 0]])
>>> k = np.array([[1,1,1],[1,1,0],[1,0,0]])
>>> from scipy import ndimage
>>> ndimage.convolve(a, k, mode='constant', cval=0.0)
array([[11, 10, 7, 4],
[10, 3, 11, 11],
[15, 12, 14, 7],
[12, 3, 7, 0]])
Setting ``cval=1.0`` is equivalent to padding the outer edge of `input`
with 1.0's (and then extracting only the original region of the result).
>>> ndimage.convolve(a, k, mode='constant', cval=1.0)
array([[13, 11, 8, 7],
[11, 3, 11, 14],
[16, 12, 14, 10],
[15, 6, 10, 5]])
With ``mode='reflect'`` (the default), outer values are reflected at the
edge of `input` to fill in missing values.
>>> b = np.array([[2, 0, 0],
[1, 0, 0],
[0, 0, 0]])
>>> k = np.array([[0,1,0],[0,1,0],[0,1,0]])
>>> ndimage.convolve(b, k, mode='reflect')
array([[5, 0, 0],
[3, 0, 0],
[1, 0, 0]])
This includes diagonally at the corners.
>>> k = np.array([[1,0,0],[0,1,0],[0,0,1]])
>>> ndimage.convolve(b, k)
array([[4, 2, 0],
[3, 2, 0],
[1, 1, 0]])
With ``mode='nearest'``, the single nearest value in to an edge in
`input` is repeated as many times as needed to match the overlapping
`weights`.
>>> c = np.array([[2, 0, 1],
[1, 0, 0],
[0, 0, 0]])
>>> k = np.array([[0, 1, 0],
[0, 1, 0],
[0, 1, 0],
[0, 1, 0],
[0, 1, 0]])
>>> ndimage.convolve(c, k, mode='nearest')
array([[7, 0, 3],
[5, 0, 2],
[3, 0, 1]])
"""
return _correlate_or_convolve(input, weights, output, mode, cval,
origin, True)
@docfiller
def uniform_filter1d(input, size, axis = -1, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""Calculate a one-dimensional uniform filter along the given axis.
The lines of the array along the given axis are filtered with a
uniform filter of given size.
Parameters
----------
%(input)s
size : integer
length of uniform filter
%(axis)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
axis = _ni_support._check_axis(axis, input.ndim)
if size < 1:
raise RuntimeError('incorrect filter size')
output, return_value = _ni_support._get_output(output, input)
if (size // 2 + origin < 0) or (size // 2 + origin >= size):
raise ValueError('invalid origin')
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.uniform_filter1d(input, size, axis, output, mode, cval,
origin)
return return_value
@docfiller
def uniform_filter(input, size = 3, output = None, mode = "reflect",
cval = 0.0, origin = 0):
"""Multi-dimensional uniform filter.
Parameters
----------
%(input)s
size : int or sequence of ints
The sizes of the uniform filter are given for each axis as a
sequence, or as a single number, in which case the size is
equal for all axes.
%(output)s
%(mode)s
%(cval)s
%(origin)s
Notes
-----
The multi-dimensional filter is implemented as a sequence of
one-dimensional uniform filters. The intermediate arrays are stored
in the same data type as the output. Therefore, for output types
with a limited precision, the results may be imprecise because
intermediate results may be stored with insufficient precision.
"""
input = numpy.asarray(input)
output, return_value = _ni_support._get_output(output, input)
sizes = _ni_support._normalize_sequence(size, input.ndim)
origins = _ni_support._normalize_sequence(origin, input.ndim)
axes = range(input.ndim)
axes = [(axes[ii], sizes[ii], origins[ii])
for ii in range(len(axes)) if sizes[ii] > 1]
if len(axes) > 0:
for axis, size, origin in axes:
uniform_filter1d(input, int(size), axis, output, mode,
cval, origin)
input = output
else:
output[...] = input[...]
return return_value
@docfiller
def minimum_filter1d(input, size, axis = -1, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""Calculate a one-dimensional minimum filter along the given axis.
The lines of the array along the given axis are filtered with a
minimum filter of given size.
Parameters
----------
%(input)s
size : int
length along which to calculate 1D minimum
%(axis)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
axis = _ni_support._check_axis(axis, input.ndim)
if size < 1:
raise RuntimeError('incorrect filter size')
output, return_value = _ni_support._get_output(output, input)
if (size // 2 + origin < 0) or (size // 2 + origin >= size):
raise ValueError('invalid origin')
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.min_or_max_filter1d(input, size, axis, output, mode, cval,
origin, 1)
return return_value
@docfiller
def maximum_filter1d(input, size, axis = -1, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""Calculate a one-dimensional maximum filter along the given axis.
The lines of the array along the given axis are filtered with a
maximum filter of given size.
Parameters
----------
%(input)s
size : int
length along which to calculate 1D maximum
%(axis)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
axis = _ni_support._check_axis(axis, input.ndim)
if size < 1:
raise RuntimeError('incorrect filter size')
output, return_value = _ni_support._get_output(output, input)
if (size // 2 + origin < 0) or (size // 2 + origin >= size):
raise ValueError('invalid origin')
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.min_or_max_filter1d(input, size, axis, output, mode, cval,
origin, 0)
return return_value
def _min_or_max_filter(input, size, footprint, structure, output, mode,
cval, origin, minimum):
if structure is None:
if footprint is None:
if size is None:
raise RuntimeError("no footprint provided")
separable= True
else:
footprint = numpy.asarray(footprint)
footprint = footprint.astype(bool)
if numpy.alltrue(numpy.ravel(footprint),axis=0):
size = footprint.shape
footprint = None
separable = True
else:
separable = False
else:
structure = numpy.asarray(structure, dtype=numpy.float64)
separable = False
if footprint is None:
footprint = numpy.ones(structure.shape, bool)
else:
footprint = numpy.asarray(footprint)
footprint = footprint.astype(bool)
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
output, return_value = _ni_support._get_output(output, input)
origins = _ni_support._normalize_sequence(origin, input.ndim)
if separable:
sizes = _ni_support._normalize_sequence(size, input.ndim)
axes = range(input.ndim)
axes = [(axes[ii], sizes[ii], origins[ii])
for ii in range(len(axes)) if sizes[ii] > 1]
if minimum:
filter_ = minimum_filter1d
else:
filter_ = maximum_filter1d
if len(axes) > 0:
for axis, size, origin in axes:
filter_(input, int(size), axis, output, mode, cval, origin)
input = output
else:
output[...] = input[...]
else:
fshape = [ii for ii in footprint.shape if ii > 0]
if len(fshape) != input.ndim:
raise RuntimeError('footprint array has incorrect shape.')
for origin, lenf in zip(origins, fshape):
if (lenf // 2 + origin < 0) or (lenf // 2 + origin >= lenf):
raise ValueError('invalid origin')
if not footprint.flags.contiguous:
footprint = footprint.copy()
if structure is not None:
if len(structure.shape) != input.ndim:
raise RuntimeError('structure array has incorrect shape')
if not structure.flags.contiguous:
structure = structure.copy()
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.min_or_max_filter(input, footprint, structure, output,
mode, cval, origins, minimum)
return return_value
@docfiller
def minimum_filter(input, size = None, footprint = None, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""Calculates a multi-dimensional minimum filter.
Parameters
----------
%(input)s
%(size_foot)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
return _min_or_max_filter(input, size, footprint, None, output, mode,
cval, origin, 1)
@docfiller
def maximum_filter(input, size = None, footprint = None, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""Calculates a multi-dimensional maximum filter.
Parameters
----------
%(input)s
%(size_foot)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
return _min_or_max_filter(input, size, footprint, None, output, mode,
cval, origin, 0)
@docfiller
def _rank_filter(input, rank, size = None, footprint = None, output = None,
mode = "reflect", cval = 0.0, origin = 0, operation = 'rank'):
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
origins = _ni_support._normalize_sequence(origin, input.ndim)
if footprint is None:
if size is None:
raise RuntimeError("no footprint or filter size provided")
sizes = _ni_support._normalize_sequence(size, input.ndim)
footprint = numpy.ones(sizes, dtype=bool)
else:
footprint = numpy.asarray(footprint, dtype=bool)
fshape = [ii for ii in footprint.shape if ii > 0]
if len(fshape) != input.ndim:
raise RuntimeError('filter footprint array has incorrect shape.')
for origin, lenf in zip(origins, fshape):
if (lenf // 2 + origin < 0) or (lenf // 2 + origin >= lenf):
raise ValueError('invalid origin')
if not footprint.flags.contiguous:
footprint = footprint.copy()
filter_size = numpy.where(footprint, 1, 0).sum()
if operation == 'median':
rank = filter_size // 2
elif operation == 'percentile':
percentile = rank
if percentile < 0.0:
percentile += 100.0
if percentile < 0 or percentile > 100:
raise RuntimeError('invalid percentile')
if percentile == 100.0:
rank = filter_size - 1
else:
rank = int(float(filter_size) * percentile / 100.0)
if rank < 0:
rank += filter_size
if rank < 0 or rank >= filter_size:
raise RuntimeError('rank not within filter footprint size')
if rank == 0:
return minimum_filter(input, None, footprint, output, mode, cval,
origin)
elif rank == filter_size - 1:
return maximum_filter(input, None, footprint, output, mode, cval,
origin)
else:
output, return_value = _ni_support._get_output(output, input)
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.rank_filter(input, rank, footprint, output, mode, cval,
origins)
return return_value
@docfiller
def rank_filter(input, rank, size = None, footprint = None, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""Calculates a multi-dimensional rank filter.
Parameters
----------
%(input)s
rank : integer
The rank parameter may be less then zero, i.e., rank = -1
indicates the largest element.
%(size_foot)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
return _rank_filter(input, rank, size, footprint, output, mode, cval,
origin, 'rank')
@docfiller
def median_filter(input, size = None, footprint = None, output = None,
mode = "reflect", cval = 0.0, origin = 0):
"""
Calculates a multi-dimensional median filter.
Parameters
----------
input : array-like
input array to filter
size : scalar or tuple, optional
See footprint, below
footprint : array, optional
Either ``size`` or ``footprint`` must be defined. ``size`` gives
the shape that is taken from the input array, at every element
position, to define the input to the filter function.
``footprint`` is a boolean array that specifies (implicitly) a
shape, but also which of the elements within this shape will get
passed to the filter function. Thus ``size=(n,m)`` is equivalent
to ``footprint=np.ones((n,m))``. We adjust ``size`` to the number
of dimensions of the input array, so that, if the input array is
shape (10,10,10), and ``size`` is 2, then the actual size used is
(2,2,2).
output : array, optional
The ``output`` parameter passes an array in which to store the
filter output.
mode : {'reflect','constant','nearest','mirror', 'wrap'}, optional
The ``mode`` parameter determines how the array borders are
handled, where ``cval`` is the value when mode is equal to
'constant'. Default is 'reflect'
cval : scalar, optional
Value to fill past edges of input if ``mode`` is 'constant'. Default
is 0.0
origin : scalar, optional
The ``origin`` parameter controls the placement of the filter.
Default 0
"""
return _rank_filter(input, 0, size, footprint, output, mode, cval,
origin, 'median')
@docfiller
def percentile_filter(input, percentile, size = None, footprint = None,
output = None, mode = "reflect", cval = 0.0, origin = 0):
"""Calculates a multi-dimensional percentile filter.
Parameters
----------
%(input)s
percentile : scalar
The percentile parameter may be less then zero, i.e.,
percentile = -20 equals percentile = 80
%(size_foot)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
"""
return _rank_filter(input, percentile, size, footprint, output, mode,
cval, origin, 'percentile')
@docfiller
def generic_filter1d(input, function, filter_size, axis = -1,
output = None, mode = "reflect", cval = 0.0, origin = 0,
extra_arguments = (), extra_keywords = None):
"""Calculate a one-dimensional filter along the given axis.
generic_filter1d iterates over the lines of the array, calling the
given function at each line. The arguments of the line are the
input line, and the output line. The input and output lines are 1D
double arrays. The input line is extended appropriately according
to the filter size and origin. The output line must be modified
in-place with the result.
Parameters
----------
%(input)s
function : callable
function to apply along given axis
filter_size : scalar
length of the filter
%(axis)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
%(extra_arguments)s
%(extra_keywords)s
"""
if extra_keywords is None:
extra_keywords = {}
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
output, return_value = _ni_support._get_output(output, input)
if filter_size < 1:
raise RuntimeError('invalid filter size')
axis = _ni_support._check_axis(axis, input.ndim)
if ((filter_size // 2 + origin < 0) or
(filter_size // 2 + origin >= filter_size)):
raise ValueError('invalid origin')
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.generic_filter1d(input, function, filter_size, axis, output,
mode, cval, origin, extra_arguments, extra_keywords)
return return_value
@docfiller
def generic_filter(input, function, size = None, footprint = None,
output = None, mode = "reflect", cval = 0.0, origin = 0,
extra_arguments = (), extra_keywords = None):
"""Calculates a multi-dimensional filter using the given function.
At each element the provided function is called. The input values
within the filter footprint at that element are passed to the function
as a 1D array of double values.
Parameters
----------
%(input)s
function : callable
function to apply at each element
%(size_foot)s
%(output)s
%(mode)s
%(cval)s
%(origin)s
%(extra_arguments)s
%(extra_keywords)s
"""
if extra_keywords is None:
extra_keywords = {}
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
origins = _ni_support._normalize_sequence(origin, input.ndim)
if footprint is None:
if size is None:
raise RuntimeError("no footprint or filter size provided")
sizes = _ni_support._normalize_sequence(size, input.ndim)
footprint = numpy.ones(sizes, dtype=bool)
else:
footprint = numpy.asarray(footprint)
footprint = footprint.astype(bool)
fshape = [ii for ii in footprint.shape if ii > 0]
if len(fshape) != input.ndim:
raise RuntimeError('filter footprint array has incorrect shape.')
for origin, lenf in zip(origins, fshape):
if (lenf // 2 + origin < 0) or (lenf // 2 + origin >= lenf):
raise ValueError('invalid origin')
if not footprint.flags.contiguous:
footprint = footprint.copy()
output, return_value = _ni_support._get_output(output, input)
mode = _ni_support._extend_mode_to_code(mode)
_nd_image.generic_filter(input, function, footprint, output, mode,
cval, origins, extra_arguments, extra_keywords)
return return_value
Jump to Line
Something went wrong with that request. Please try again.