def orient_by_streamline(streamlines,
standard,
n_points=12,
in_place=False,
as_generator=False,
affine=None):
"""
Orient a bundle of streamlines to a standard streamline.
Parameters
----------
streamlines : Streamlines, list
The input streamlines to orient.
standard : Streamlines, list, or ndarrray
This provides the standard orientation according to which the
streamlines in the provided bundle should be reoriented.
n_points: int, optional
The number of samples to apply to each of the streamlines.
in_place : bool
Whether to make the change in-place in the original input
(and return a reference), or to make a copy of the list
and return this copy, with the relevant streamlines reoriented.
Default: False.
as_generator : bool
Whether to return a generator as output. Default: False
affine : ndarray
Affine transformation from voxels to streamlines. Default: identity.
Returns
-------
Streamlines : with each individual array oriented to be as similar as
possible to the standard.
"""
# Start by resampling, so that distance calculation is easy:
fgarray = set_number_of_points(streamlines, n_points)
std_array = set_number_of_points([standard], n_points)
if as_generator:
if in_place:
w_s = "Cannot return a generator when in_place is set to True"
raise ValueError(w_s)
return _orient_by_sl_generator(streamlines, std_array, fgarray)
# If it's a generator on input, we may as well generate it
# here and now:
if isinstance(streamlines, types.GeneratorType):
out = Streamlines(streamlines)
elif in_place:
out = streamlines
else:
# Make a copy, so you don't change the output in place:
out = deepcopy(streamlines)
return _orient_by_sl_list(out, std_array, fgarray)
def orient_by_streamline(streamlines, standard, n_points=12, in_place=False,
as_generator=False, affine=None):
"""
Orient a bundle of streamlines to a standard streamline.
Parameters
----------
streamlines : Streamlines, list
The input streamlines to orient.
standard : Streamlines, list, or ndarrray
This provides the standard orientation according to which the
streamlines in the provided bundle should be reoriented.
n_points: int, optional
The number of samples to apply to each of the streamlines.
in_place : bool
Whether to make the change in-place in the original input
(and return a reference), or to make a copy of the list
and return this copy, with the relevant streamlines reoriented.
Default: False.
as_generator : bool
Whether to return a generator as output. Default: False
affine : ndarray
Affine transformation from voxels to streamlines. Default: identity.
Returns
-------
Streamlines : with each individual array oriented to be as similar as
possible to the standard.
"""
# Start by resampling, so that distance calculation is easy:
fgarray = set_number_of_points(streamlines, n_points)
std_array = set_number_of_points([standard], n_points)
if as_generator:
if in_place:
w_s = "Cannot return a generator when in_place is set to True"
raise ValueError(w_s)
return _orient_by_sl_generator(streamlines, std_array, fgarray)
# If it's a generator on input, we may as well generate it
# here and now:
if isinstance(streamlines, types.GeneratorType):
out = Streamlines(streamlines)
elif in_place:
out = streamlines
else:
# Make a copy, so you don't change the output in place:
out = deepcopy(streamlines)
return _orient_by_sl_list(out, std_array, fgarray)
def find_bad_nrigh(name, score):
test_data = np.load(os.path.join('..', 'cci_clean_data', name))
data_evl = test_data['arr_0']
key = os.path.splitext(name)[0]
cci_score = cci_dict[key]
cci_score = np.array(cci_score)
streamlines_evl = Streamlines()
for i in range(np.shape(data_evl)[0]):
tmp = data_evl[i]
tmp = zero_remove(tmp)
#tmp = tmp[~np.all(tmp == 0, axis=-1)]
#tmp = np.around(tmp, decimals=0)
streamlines_evl.append(tmp)
lengths = np.array(list(length(streamlines_evl)))
neighb = np.zeros((np.shape(data_evl)[0]))
subsamp_sls = set_number_of_points(streamlines_evl, 64)
for i in range(len(streamlines_evl)):
mdf_mx = bundles_distances_mdf([subsamp_sls[i]], subsamp_sls)
if (score[i] == 0): # bad fiber
thre = np.percentile(mdf_mx, 4)
len_bad = lengths[i]
bound = len_bad * 0.1
len_limt = 1 * ((lengths > len_bad - bound) &
(lengths < len_bad + bound))
label = 1 * (mdf_mx < thre).flatten() # bad neighbour
neighb = neighb + label * (cci_score < 10)
return data_evl, neighb
def resample_streamlines_num_points(sft, num_points):
"""
Resample streamlines using number of points per streamline
Parameters
----------
sft: StatefulTractogram
SFT containing the streamlines to subsample.
num_points: int
Number of points per streamline in the output.
Return
------
resampled_sft: StatefulTractogram
The resampled streamlines as a sft.
"""
# Checks
if num_points <= 1:
raise ValueError("The value of num_points should be greater than 1!")
# Resampling
resampled_streamlines = []
for streamline in sft.streamlines:
line = set_number_of_points(streamline, num_points)
resampled_streamlines.append(line)
# Creating sft
# CAREFUL. Data_per_point will be lost.
resampled_sft = _warn_and_save(resampled_streamlines, sft)
return resampled_sft
def _resample_tg(tg, n_points):
# reformat for dipy's set_number_of_points
if isinstance(tg, np.ndarray):
if len(tg.shape) > 2:
streamlines = tg.tolist()
streamlines = [np.asarray(item) for item in streamlines]
else:
streamlines = tg.streamlines
return dps.set_number_of_points(streamlines, n_points)
def remove_indentical(n, streamlines_ori):
for i in range(n):
error_index = []
subsamp_sls = set_number_of_points(streamlines_ori, 64)
mdf1 = np.zeros((1, len(subsamp_sls)))
for i, sl in enumerate(subsamp_sls):
mdf_mx = bundles_distances_mdf([subsamp_sls[i]], subsamp_sls)
mdf1 = np.vstack((mdf1, mdf_mx))
if (mdf_mx == 0).sum() > 1:
if i - 1 not in error_index:
error_index.append(i)
if error_index == []:
return streamlines_ori
print('number of detecting iteration is ' + str(2 * i + 1))
break
streamlines_evl_final1 = Streamlines()
for i, sl in enumerate(streamlines_ori):
if i not in error_index:
streamlines_evl_final1.append(sl)
error_index = []
subsamp_sls = set_number_of_points(streamlines_evl_final1, 64)
mdf1 = np.zeros((1, len(subsamp_sls)))
for i, sl in enumerate(subsamp_sls):
mdf_mx = bundles_distances_mdf([subsamp_sls[i]], subsamp_sls)
mdf1 = np.vstack((mdf1, mdf_mx))
if (mdf_mx == 0).sum() > 1:
if i - 1 not in error_index:
error_index.append(i)
if error_index == []:
return streamlines_evl_final1
print('number of detecting iteration is ' + str(2 * i + 2))
break
streamlines_ori = Streamlines()
for i, sl in enumerate(streamlines_evl_final1):
if i not in error_index:
streamlines_ori.append(sl)
def gaussian_weights(bundle, n_points=100):
"""
Calculate weights for each streamline/node in a bundle, based on a
Mahalanobis distance from the mean of the bundle, at that node
Parameters
----------
bundle : array or list
If this is a list, assume that it is a list of streamline coordinates
(each entry is a 2D array, of shape n by 3). If this is an array, this
is a resampled version of the streamlines, with equal number of points
in each streamline.
n_points : int, optional
The number of points to resample to. *If the `bundle` is an array, this
input is ignored*. Default: 100.
Returns
-------
w : array of shape (n_streamlines, n_points)
Weights for each node in each streamline, calculated as its relative
inverse of the Mahalanobis distance, relative to the distribution of
coordinates at that node position across streamlines.
"""
if isinstance(bundle, list):
# if you got a list, assume that it needs to be resampled:
bundle = np.array(dps.set_number_of_points(bundle, n_points))
else:
if bundle.shape[-1] != 3:
e_s = "Input must be shape (n_streamlines, n_points, 3)"
raise ValueError(e_s)
n_points = bundle.shape[1]
w = np.zeros((bundle.shape[0], n_points))
for node in range(bundle.shape[1]):
# This should come back as a 3D covariance matrix with the spatial
# variance covariance of this node across the different streamlines
# This is a 3-by-3 array:
node_coords = bundle[:, node]
c = np.cov(node_coords.T, ddof=0)
# Calculate the mean or median of this node as well
# delta = node_coords - np.mean(node_coords, 0)
m = np.mean(node_coords, 0)
# Weights are the inverse of the Mahalanobis distance
for fn in range(bundle.shape[0]):
# calculate Mahalanobis for node on fiber[fn]
w[fn, node] = mahalanobis(node_coords[fn], m, c)
# weighting is inverse to the distance (the further you are, the less you
# should be weighted)
w = 1 / w
# Normalize before returning, so that the weights in each node sum to 1:
return w / np.sum(w, 0)
def gaussian_weights(bundle, n_points=100):
"""
Calculate weights for each streamline/node in a bundle, based on a
Mahalanobis distance from the mean of the bundle, at that node
Parameters
----------
bundle : array or list
If this is a list, assume that it is a list of streamline coordinates
(each entry is a 2D array, of shape n by 3). If this is an array, this
is a resampled version of the streamlines, with equal number of points
in each streamline.
n_points : int, optional
The number of points to resample to. *If the `bundle` is an array, this
input is ignored*. Default: 100.
Returns
-------
w : array of shape (n_streamlines, n_points)
Weights for each node in each streamline, calculated as its relative
inverse of the Mahalanobis distance, relative to the distribution of
coordinates at that node position across streamlines.
"""
if isinstance(bundle, list):
# if you got a list, assume that it needs to be resampled:
bundle = np.array(dps.set_number_of_points(bundle, n_points))
else:
if bundle.shape[-1] != 3:
e_s = "Input must be shape (n_streamlines, n_points, 3)"
raise ValueError(e_s)
n_points = bundle.shape[1]
w = np.zeros((bundle.shape[0], n_points))
for node in range(bundle.shape[1]):
# This should come back as a 3D covariance matrix with the spatial
# variance covariance of this node across the different streamlines
# This is a 3-by-3 array:
node_coords = bundle[:, node]
c = np.cov(node_coords.T, ddof=0)
# Calculate the mean or median of this node as well
# delta = node_coords - np.mean(node_coords, 0)
m = np.mean(node_coords, 0)
# Weights are the inverse of the Mahalanobis distance
for fn in range(bundle.shape[0]):
# calculate Mahalanobis for node on fiber[fn]
w[fn, node] = mahalanobis(node_coords[fn], m, c)
# weighting is inverse to the distance (the further you are, the less you
# should be weighted)
w = 1 / w
# Normalize before returning, so that the weights in each node sum to 1:
return w / np.sum(w, 0)
def resample_streamlines_step_size(sft, step_size):
"""
Resample streamlines using a fixed step size.
Parameters
----------
sft: StatefulTractogram
SFT containing the streamlines to subsample.
step_size: float
Size of the new steps, in mm.
Return
------
resampled_sft: StatefulTractogram
The resampled streamlines as a sft.
"""
# Checks
if step_size == 0:
raise ValueError("Step size can't be 0!")
elif step_size < 0.1:
logging.debug("The value of your step size seems suspiciously low. "
"Please check.")
elif step_size > np.max(sft.voxel_sizes):
logging.debug("The value of your step size seems suspiciously high. "
"Please check.")
# Make sure we are in world space
orig_space = sft.space
sft.to_rasmm()
# Resampling
lengths = length(sft.streamlines)
nb_points = np.ceil(lengths / step_size).astype(int)
if np.any(nb_points == 1):
logging.warning("Some streamlines are shorter than the provided "
"step size...")
nb_points[nb_points == 1] = 2
resampled_streamlines = [
set_number_of_points(s, n) for s, n in zip(sft.streamlines, nb_points)
]
# Creating sft
resampled_sft = _warn_and_save(resampled_streamlines, sft)
# Return to original space
resampled_sft.to_space(orig_space)
return resampled_sft
def smooth_line_gaussian(streamline, sigma):
if sigma < 0.00001:
ValueError('Cant have a 0 sigma with gaussian.')
nb_points = int(length(streamline))
if nb_points < 2:
logging.debug('Streamline shorter than 1mm, corner cases possible.')
nb_points = 2
sampled_streamline = set_number_of_points(streamline, nb_points)
x, y, z = sampled_streamline.T
x3 = gaussian_filter1d(x, sigma)
y3 = gaussian_filter1d(y, sigma)
z3 = gaussian_filter1d(z, sigma)
smoothed_streamline = np.asarray([x3, y3, z3]).T
# Ensure first and last point remain the same
smoothed_streamline[0] = streamline[0]
smoothed_streamline[-1] = streamline[-1]
return smoothed_streamline
def smooth_line_spline(streamline, sigma, nb_ctrl_points):
if sigma < 0.00001:
ValueError('Cant have a 0 sigma with spline.')
nb_points = int(length(streamline))
if nb_points < 2:
logging.debug('Streamline shorter than 1mm, corner cases possible.')
if nb_ctrl_points < 3:
nb_ctrl_points = 3
sampled_streamline = set_number_of_points(streamline, nb_ctrl_points)
tck, u = splprep(sampled_streamline.T, s=sigma)
smoothed_streamline = splev(np.linspace(0, 1, 99), tck)
smoothed_streamline = np.squeeze(np.asarray([smoothed_streamline]).T)
# Ensure first and last point remain the same
smoothed_streamline[0] = streamline[0]
smoothed_streamline[-1] = streamline[-1]
return smoothed_streamline
def calculate_tract_profile(img,
streamlines,
affine=None,
n_points=100,
weights=None):
"""
Parameters
----------
img : 3D volume
streamlines : list of arrays, or array
weights : 1D array or 2D array (optional)
Weight each streamline (1D) or each node (2D) when calculating the
tract-profiles. Must sum to 1 across streamlines (in each node if
relevant).
"""
if isinstance(streamlines, list):
# Resample each streamline to the same number of points
# list => np.array
# Setting the number of points should happen in a streamline template
# space, rather than in the subject native space, but for now we do
# everything as in the Matlab version -- in native space.
# In the future, an SLR object can be passed here, and then it would
# move these streamlines into the template space before resampling...
fgarray = np.array(dps.set_number_of_points(streamlines, n_points))
else:
fgarray = streamlines
# ...and move them back to native space before indexing into the volume:
values = dts.values_from_volume(img, fgarray, affine=affine)
# We assume that weights *always sum to 1 across streamlines*:
if weights is None:
weights = np.ones(values.shape) / values.shape[0]
tract_profile = np.sum(weights * values, 0)
return tract_profile
def gen_short_data(name_list):
for i in range(len(name_list)):
name = name_list[i]
path = os.path.join('..', 'cci_clean_data', name)
sample_data = np.load(path)
ndata = sample_data['arr_0']
streamlines_evl = Streamlines()
for j in range(np.shape(ndata)[0]):
tmp = ndata[j]
tmp = zero_remove(tmp)
streamlines_evl.append(tmp)
subsamp_sls = set_number_of_points(streamlines_evl, sub_len)
tt = np.array(subsamp_sls)
path = os.path.join('..', 'subsample-data', str(sub_len))
if not os.path.exists(path):
os.makedirs(path)
name_save = os.path.join(path, os.path.splitext(name)[0])
np.savez_compressed(name_save, tt)
print(str(i + 1) + '/141 finished')
def calculate_tract_profile(img, streamlines, affine=None, n_points=100,
weights=None):
"""
Parameters
----------
img : 3D volume
streamlines : list of arrays, or array
weights : 1D array or 2D array (optional)
Weight each streamline (1D) or each node (2D) when calculating the
tract-profiles. Must sum to 1 across streamlines (in each node if
relevant).
"""
if isinstance(streamlines, list):
# Resample each streamline to the same number of points
# list => np.array
# Setting the number of points should happen in a streamline template
# space, rather than in the subject native space, but for now we do
# everything as in the Matlab version -- in native space.
# In the future, an SLR object can be passed here, and then it would
# move these streamlines into the template space before resampling...
fgarray = np.array(dps.set_number_of_points(streamlines, n_points))
else:
fgarray = streamlines
# ...and move them back to native space before indexing into the volume:
values = dts.values_from_volume(img, fgarray, affine=affine)
# We assume that weights *always sum to 1 across streamlines*:
if weights is None:
weights = np.ones(values.shape) / values.shape[0]
tract_profile = np.sum(weights * values, 0)
return tract_profile
def segment(self,
bundle_dict,
tg,
fdata=None,
fbval=None,
fbvec=None,
mapping=None,
reg_prealign=None,
reg_template=None,
b0_threshold=0,
img_affine=None):
"""
Segment streamlines into bundles based on either waypoint ROIs
[Yeatman2012]_ or RecoBundles [Garyfallidis2017]_.
Parameters
----------
bundle_dict: dict
Meta-data for the segmentation. The format is something like::
{'name': {'ROIs':[img1, img2],
'rules':[True, True]},
'prob_map': img3,
'cross_midline': False}
tg : StatefulTractogram
Bundles to segment
fdata, fbval, fbvec : str
Full path to data, bvals, bvecs
mapping : DiffeomorphicMap object, str or nib.Nifti1Image, optional.
A mapping between DWI space and a template. If None, mapping will
be registered from data used in prepare_img. Default: None.
reg_prealign : array, optional.
The linear transformation to be applied to align input images to
the reference space before warping under the deformation field.
Default: None.
reg_template : str or nib.Nifti1Image, optional.
Template to use for registration. Default: MNI T2.
img_affine : array, optional.
The spatial transformation from the measurement to the scanner
space.
References
----------
.. [Yeatman2012] Yeatman, Jason D., Robert F. Dougherty, Nathaniel J.
Myall, Brian A. Wandell, and Heidi M. Feldman. 2012. "Tract Profiles of
White Matter Properties: Automating Fiber-Tract Quantification"
PloS One 7 (11): e49790.
.. [Garyfallidis17] Garyfallidis et al. Recognition of white matter
bundles using local and global streamline-based registration and
clustering, Neuroimage, 2017.
"""
if img_affine is not None:
if (mapping is None or fdata is not None or fbval is not None
or fbvec is not None):
self.logger.error(
"Provide either the full path to data, bvals, bvecs," +
"or provide the affine of the image and the mapping")
self.logger.info("Preparing Segmentation Parameters")
self.img_affine = img_affine
self.prepare_img(fdata, fbval, fbvec)
self.logger.info("Preprocessing Streamlines")
self.tg = tg
# If resampling over-write the sft:
if self.nb_points:
self.tg = StatefulTractogram(
dps.set_number_of_points(self.tg.streamlines, self.nb_points),
self.tg, self.tg.space)
self.resample_streamlines(self.nb_points)
self.prepare_map(mapping, reg_prealign, reg_template)
self.bundle_dict = bundle_dict
self.cross_streamlines()
if self.seg_algo == "afq":
return self.segment_afq()
elif self.seg_algo == "reco":
return self.segment_reco()
def cluster_confidence(streamlines,
max_mdf=5,
subsample=12,
power=1,
override=False):
""" Computes the cluster confidence index (cci), which is an
estimation of the support a set of streamlines gives to
a particular pathway.
Ex: A single streamline with no others in the dataset
following a similar pathway has a low cci. A streamline
in a bundle of 100 streamlines that follow similar
pathways has a high cci.
See: Jordan et al. 2017
(Based on streamline MDF distance from Garyfallidis et al. 2012)
Parameters
----------
streamlines : list of 2D (N, 3) arrays
A sequence of streamlines of length N (# streamlines)
max_mdf : int
The maximum MDF distance (mm) that will be considered a
"supporting" streamline and included in cci calculation
subsample: int
The number of points that are considered for each streamline
in the calculation. To save on calculation time, each
streamline is subsampled to subsampleN points.
power: int
The power to which the MDF distance for each streamline
will be raised to determine how much it contributes to
the cci. High values of power make the contribution value
degrade much faster. Example: a streamline with 5mm MDF
similarity contributes 1/5 to the cci if power is 1, but
only contributes 1/5^2 = 1/25 if power is 2.
override: bool, False by default
override means that the cci calculation will still occur even
though there are short streamlines in the dataset that may alter
expected behaviour.
Returns
-------
Returns an array of CCI scores
References
----------
[Jordan17] Jordan K. Et al., Cluster Confidence Index: A Streamline-Wise
Pathway Reproducibility Metric for Diffusion-Weighted MRI Tractography,
Journal of Neuroimaging, vol 28, no 1, 2017.
[Garyfallidis12] Garyfallidis E. et al., QuickBundles a method for
tractography simplification, Frontiers in Neuroscience,
vol 6, no 175, 2012.
"""
# error if any streamlines are shorter than 20mm
lengths = list(length(streamlines))
if min(lengths) < 20 and not override:
raise ValueError('Short streamlines found. We recommend removing them.'
' To continue without removing short streamlines set'
' override=True')
# calculate the pairwise MDF distance between all streamlines in dataset
subsamp_sls = set_number_of_points(streamlines, subsample)
cci_score_mtrx = np.zeros([len(subsamp_sls)])
for i, sl in enumerate(subsamp_sls):
mdf_mx = bundles_distances_mdf([subsamp_sls[i]], subsamp_sls)
if (mdf_mx == 0).sum() > 1:
raise ValueError('Identical streamlines. CCI calculation invalid')
mdf_mx_oi = (mdf_mx > 0) & (mdf_mx < max_mdf) & ~np.isnan(mdf_mx)
mdf_mx_oi_only = mdf_mx[mdf_mx_oi]
cci_score = np.sum(np.divide(1, np.power(mdf_mx_oi_only, power)))
cci_score_mtrx[i] = cci_score
return cci_score_mtrx
def _resample_bundle(streamlines, n_points):
return np.array(dps.set_number_of_points(streamlines, n_points))
def cluster_confidence(streamlines, max_mdf=5, subsample=12, power=1,
override=False):
""" Computes the cluster confidence index (cci), which is an
estimation of the support a set of streamlines gives to
a particular pathway.
Ex: A single streamline with no others in the dataset
following a similar pathway has a low cci. A streamline
in a bundle of 100 streamlines that follow similar
pathways has a high cci.
See: Jordan et al. 2017
(Based on streamline MDF distance from Garyfallidis et al. 2012)
Parameters
----------
streamlines : list of 2D (N, 3) arrays
A sequence of streamlines of length N (# streamlines)
max_mdf : int
The maximum MDF distance (mm) that will be considered a
"supporting" streamline and included in cci calculation
subsample: int
The number of points that are considered for each streamline
in the calculation. To save on calculation time, each
streamline is subsampled to subsampleN points.
power: int
The power to which the MDF distance for each streamline
will be raised to determine how much it contributes to
the cci. High values of power make the contribution value
degrade much faster. Example: a streamline with 5mm MDF
similarity contributes 1/5 to the cci if power is 1, but
only contributes 1/5^2 = 1/25 if power is 2.
override: bool, False by default
override means that the cci calculation will still occur even
though there are short streamlines in the dataset that may alter
expected behaviour.
Returns
-------
Returns an array of CCI scores
References
----------
[Jordan17] Jordan K. Et al., Cluster Confidence Index: A Streamline-Wise
Pathway Reproducibility Metric for Diffusion-Weighted MRI Tractography,
Journal of Neuroimaging, vol 28, no 1, 2017.
[Garyfallidis12] Garyfallidis E. et al., QuickBundles a method for
tractography simplification, Frontiers in Neuroscience,
vol 6, no 175, 2012.
"""
# error if any streamlines are shorter than 20mm
lengths = list(length(streamlines))
if min(lengths) < 20 and not override:
raise ValueError('Short streamlines found. We recommend removing them.'
' To continue without removing short streamlines set'
' override=True')
# calculate the pairwise MDF distance between all streamlines in dataset
subsamp_sls = set_number_of_points(streamlines, subsample)
cci_score_mtrx = np.zeros([len(subsamp_sls)])
for i, sl in enumerate(subsamp_sls):
mdf_mx = bundles_distances_mdf([subsamp_sls[i]], subsamp_sls)
if (mdf_mx == 0).sum() > 1:
raise ValueError('Identical streamlines. CCI calculation invalid')
mdf_mx_oi = (mdf_mx > 0) & (mdf_mx < max_mdf) & ~ np.isnan(mdf_mx)
mdf_mx_oi_only = mdf_mx[mdf_mx_oi]
cci_score = np.sum(np.divide(1, np.power(mdf_mx_oi_only, power)))
cci_score_mtrx[i] = cci_score
return cci_score_mtrx
def resample_streamlines(streamlines, n_pts=16):
resampled = []
for sl in streamlines:
resampled.append(set_number_of_points(sl, n_pts))
return resampled
def _resample_bundle(streamlines, n_points):
return np.array(dps.set_number_of_points(streamlines, n_points))
