def get_roi_center(roi_native_path, roi_mni_path):
"""Get ROI center of mass.
Get back coordinate in img space and in coordinate space.
Also actual center of mass.
"""
# computations in native space
if type(roi_native_path) is str:
img = nib.load(roi_native_path)
else:
img = roi_native_path
data = img.get_data()
data = as_ndarray(data)
my_map = data.copy()
center_coords = ndimage.center_of_mass(np.abs(my_map))
x_map, y_map, z_map = center_coords[:3]
native_coords = np.asarray(coord_transform(x_map, y_map, z_map,
img.get_affine())).tolist()
voxel = [round(x) for x in center_coords]
# computations in mni space
if type(roi_mni_path) is str:
img = nib.load(roi_mni_path)
else:
img = roi_mni_path
data = img.get_data()
data = as_ndarray(data)
my_map = data.copy()
mni_center_coords = ndimage.center_of_mass(np.abs(my_map))
x_map, y_map, z_map = mni_center_coords[:3]
mni_coords = np.asarray(coord_transform(x_map, y_map, z_map,
img.get_affine())).tolist()
# returns voxel and true center mass coords
# returns also native and mni space coords
return (voxel[:3], center_coords[:3], [round(x) for x in native_coords],
[round(x) for x in mni_coords])
def test_coord_transform_trivial():
sform = np.eye(4)
x = np.random.random((10, ))
y = np.random.random((10, ))
z = np.random.random((10, ))
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x, x_)
np.testing.assert_array_equal(y, y_)
np.testing.assert_array_equal(z, z_)
sform[:, -1] = 1
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the output in case of one item array
x, y, z = x[:1], y[:1], z[:1]
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the output in case of simple items
x, y, z = x[0], y[0], z[0]
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
def test_coord_transform_trivial():
sform = np.eye(4)
x = np.random.random((10,))
y = np.random.random((10,))
z = np.random.random((10,))
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x, x_)
np.testing.assert_array_equal(y, y_)
np.testing.assert_array_equal(z, z_)
sform[:, -1] = 1
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the output in case of one item array
x, y, z = x[:1], y[:1], z[:1]
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the output in case of simple items
x, y, z = x[0], y[0], z[0]
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
def _get_mask_measures(mask_file):
""" Outputs the mask
Parameters
----------
mask_file : str
Path to the mask image
"""
mask_img = nibabel.load(mask_file)
volume = _get_volume(mask_img)
mask_data = mask_img.get_data()
i, j, k = np.where(mask_data != 0)
voxels_coords = np.array(coord_transform(i, j, k, mask_img.affine)).T
positions = np.vstack((i, j, k)).T
center = ndimage.center_of_mass(mask_data)
center_coords = np.array(
coord_transform(center[0], center[1], center[2], mask_img.affine)).T
positions = voxels_coords - center_coords # TODO: check why not voxels_coords.mean(axis=0)
inertia_matrix = -positions.T.dot(positions) / float(len(positions))
total_sum = -np.diag(inertia_matrix).sum()
inertia_matrix += np.eye(3) * total_sum
_, eigvecs = np.linalg.eigh(inertia_matrix)
axis_ap, axis_rl, axis_is = eigvecs.T
# Translation to image centroid
translation = np.eye(4)
translation[:3, 3] = -center_coords #voxels_coords.mean(axis=0)
# Reorientation with respect to the principal axes
reorientation = np.eye(4)
reorientation[:3, 0] = axis_rl
reorientation[:3, 1] = axis_ap
reorientation[:3, 2] = axis_is
affine = np.linalg.inv(translation).dot(reorientation).dot(
translation).dot(mask_img.affine)
reoriented_img = resample_img(mask_img, affine, interpolation='nearest')
zooms = reoriented_img.header.get_zooms()
reoriented_data = reoriented_img.get_data()
reoriented_center = ndimage.center_of_mass(reoriented_data)
reoriented_center = np.array(reoriented_center, dtype=int)
length_rl = zooms[0] * reoriented_data[:, reoriented_center[1],
reoriented_center[2]].sum()
length_ap = zooms[1] * reoriented_data[reoriented_center[0], :,
reoriented_center[2]].sum()
length_is = zooms[2] * reoriented_data[reoriented_center[0],
reoriented_center[1]].sum()
# Reflection along the RL axis
reflection = np.eye(4)
reflection[0, 0] = -1
affine = np.linalg.inv(translation).dot(reorientation).dot(reflection).dot(
translation).dot(mask_img.affine)
reflected_reoriented_img = resample_img(mask_img,
target_affine=affine,
target_shape=reoriented_data.shape,
interpolation='nearest')
reflected_reoriented_data = reflected_reoriented_img.get_data()
symmetry = stats.pearsonr(reoriented_data.ravel(),
reflected_reoriented_data.ravel())[0]
return (length_ap, length_rl, length_is, symmetry, volume)
def test_sample_locations():
# check positions of samples on toy example, with an affine != identity
# flat horizontal mesh
mesh = flat_mesh(5, 7)
affine = np.diagflat([10, 20, 30, 1])
inv_affine = np.linalg.inv(affine)
# transform vertices to world space
vertices = np.asarray(
resampling.coord_transform(*mesh[0].T, affine=affine)).T
# compute by hand the true offsets in voxel space
# (transformed by affine^-1)
ball_offsets = surface._load_uniform_ball_cloud(10)
ball_offsets = np.asarray(
resampling.coord_transform(*ball_offsets.T, affine=inv_affine)).T
line_offsets = np.zeros((10, 3))
line_offsets[:, 2] = np.linspace(1, -1, 10)
line_offsets = np.asarray(
resampling.coord_transform(*line_offsets.T, affine=inv_affine)).T
# check we get the same locations
for kind, offsets in [('line', line_offsets), ('ball', ball_offsets)]:
locations = surface._sample_locations(
[vertices, mesh[1]], affine, 1., kind=kind, n_points=10)
true_locations = np.asarray([vertex + offsets for vertex in mesh[0]])
assert_array_equal(locations.shape, true_locations.shape)
assert_array_almost_equal(true_locations, locations)
pytest.raises(ValueError, surface._sample_locations,
mesh, affine, 1., kind='bad_kind')
def test_sample_locations():
# check positions of samples on toy example, with an affine != identity
# flat horizontal mesh
mesh = flat_mesh(5, 7)
affine = np.diagflat([10, 20, 30, 1])
inv_affine = np.linalg.inv(affine)
# transform vertices to world space
vertices = np.asarray(
resampling.coord_transform(*mesh[0].T, affine=affine)).T
# compute by hand the true offsets in voxel space
# (transformed by affine^-1)
ball_offsets = surface._load_uniform_ball_cloud(10)
ball_offsets = np.asarray(
resampling.coord_transform(*ball_offsets.T, affine=inv_affine)).T
line_offsets = np.zeros((10, 3))
line_offsets[:, 2] = np.linspace(-1, 1, 10)
line_offsets = np.asarray(
resampling.coord_transform(*line_offsets.T, affine=inv_affine)).T
# check we get the same locations
for kind, offsets in [('line', line_offsets), ('ball', ball_offsets)]:
locations = surface._sample_locations(
[vertices, mesh[1]], affine, 1., kind=kind, n_points=10)
true_locations = np.asarray([vertex + offsets for vertex in mesh[0]])
assert_array_equal(locations.shape, true_locations.shape)
assert_array_almost_equal(true_locations, locations)
assert_raises(ValueError, surface._sample_locations,
mesh, affine, 1., kind='bad_kind')
def get_roi_center(roi_native_path, roi_mni_path):
"""Get ROI center of mass.
Get back coordinate in img space and in coordinate space.
Also actual center of mass.
"""
# computations in native space
if type(roi_native_path) is str:
img = nib.load(roi_native_path)
else:
img = roi_native_path
data = img.get_data()
data = as_ndarray(data)
my_map = data.copy()
center_coords = ndimage.center_of_mass(np.abs(my_map))
x_map, y_map, z_map = center_coords[:3]
native_coords = np.asarray(
coord_transform(x_map, y_map, z_map, img.get_affine())).tolist()
voxel = [round(x) for x in center_coords]
# computations in mni space
if type(roi_mni_path) is str:
img = nib.load(roi_mni_path)
else:
img = roi_mni_path
data = img.get_data()
data = as_ndarray(data)
my_map = data.copy()
mni_center_coords = ndimage.center_of_mass(np.abs(my_map))
x_map, y_map, z_map = mni_center_coords[:3]
mni_coords = np.asarray(
coord_transform(x_map, y_map, z_map, img.get_affine())).tolist()
# returns voxel and true center mass coords
# returns also native and mni space coords
return (voxel[:3], center_coords[:3], [round(x) for x in native_coords],
[round(x) for x in mni_coords])
def _ball_sample_locations(mesh,
affine,
ball_radius=3.,
n_points=20,
depth=None):
"""Locations to draw samples from to project volume data onto a mesh.
For each mesh vertex, the locations of `n_points` points evenly spread in a
ball around the vertex are returned.
Parameters
----------
mesh : pair of np arrays.
`mesh[0]` contains the 3d coordinates of the vertices
(shape n_vertices, 3)
`mesh[1]` contains, for each triangle, the indices into `mesh[0]` of its
vertices (shape n_triangles, 3)
affine : array of shape (4, 4)
Affine transformation from image voxels to the vertices' coordinate
space.
ball_radius : float, optional
Size in mm of the neighbourhood around each vertex in which to draw
samples. Default=3.0.
n_points : int, optional
Number of samples to draw for each vertex. Default=20.
depth : None
Raises a ValueError if not None because incompatible with this sampling
strategy.
Returns
-------
sample_location_voxel_space : numpy array, shape (n_vertices, n_points, 3)
The locations, in voxel space, from which to draw samples.
First dimension iterates over mesh vertices, second dimension iterates
over the sample points associated to a vertex, third dimension is x, y,
z in voxel space.
"""
if depth is not None:
raise ValueError("The 'ball' sampling strategy does not support "
"the 'depth' parameter")
vertices, faces = mesh
offsets_world_space = _load_uniform_ball_cloud(
n_points=n_points) * ball_radius
mesh_voxel_space = np.asarray(
resampling.coord_transform(*vertices.T,
affine=np.linalg.inv(affine))).T
linear_map = np.eye(affine.shape[0])
linear_map[:-1, :-1] = affine[:-1, :-1]
offsets_voxel_space = np.asarray(
resampling.coord_transform(*offsets_world_space.T,
affine=np.linalg.inv(linear_map))).T
sample_locations_voxel_space = (mesh_voxel_space[:, np.newaxis, :] +
offsets_voxel_space[np.newaxis, :])
return sample_locations_voxel_space
def _get_affinity(seeds, coords, radius, allow_overlap, affine, mask_img=None):
seeds = list(seeds)
# Compute world coordinates of all in-mask voxels.
mask_coords = list(zip(*coords.T))
# For each seed, get coordinates of nearest voxel
nearests = []
for sx, sy, sz in seeds:
nearest = np.round(coord_transform(sx, sy, sz, np.linalg.inv(affine)))
nearest = nearest.astype(int)
nearest = (nearest[0], nearest[1], nearest[2])
try:
nearests.append(mask_coords.index(nearest))
except ValueError:
nearests.append(None)
mask_coords = np.asarray(list(zip(*mask_coords)))
mask_coords = coord_transform(mask_coords[0], mask_coords[1],
mask_coords[2], affine)
mask_coords = np.asarray(mask_coords).T
if (radius is not None and
LooseVersion(sklearn.__version__) < LooseVersion('0.16')):
# Fix for scikit learn versions below 0.16. See
# https://github.com/scikit-learn/scikit-learn/issues/4072
radius += 1e-6
clf = neighbors.NearestNeighbors(radius=radius)
A = clf.fit(mask_coords).radius_neighbors_graph(seeds)
A = A.tolil()
for i, nearest in enumerate(nearests):
if nearest is None:
continue
A[i, nearest] = True
# Include the voxel containing the seed itself if not masked
mask_coords = mask_coords.astype(int).tolist()
for i, seed in enumerate(seeds):
try:
A[i, mask_coords.index(seed)] = True
except ValueError:
# seed is not in the mask
pass
if not allow_overlap:
if np.any(A.sum(axis=0) >= 2):
raise ValueError('Overlap detected between spheres')
return A
def test_coord_transform_trivial():
sform = np.eye(4)
x = np.random.random((10,))
y = np.random.random((10,))
z = np.random.random((10,))
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x, x_)
np.testing.assert_array_equal(y, y_)
np.testing.assert_array_equal(z, z_)
sform[:, -1] = 1
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
def index_to_xy_coord(x, y, z=10):
'''Transforms data index to coordinates of the background + offset'''
coords = coord_transform(x,
y,
z,
affine=thresholded_score_map_img.get_affine())
return np.array(coords)[np.newaxis, :] + np.array([0, 1, 0])
def test_coord_transform_trivial():
sform = np.eye(4)
x = np.random.random((10, ))
y = np.random.random((10, ))
z = np.random.random((10, ))
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x, x_)
np.testing.assert_array_equal(y, y_)
np.testing.assert_array_equal(z, z_)
sform[:, -1] = 1
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
def _line_sample_locations(mesh,
affine,
segment_half_width=3.,
n_points=10,
depth=None):
"""Locations to draw samples from to project volume data onto a mesh.
For each mesh vertex, the locations of `n_points` points evenly spread in a
segment of the normal to the vertex are returned. The line segment has
length 2 * `segment_half_width` and is centered at the vertex.
Parameters
----------
mesh : pair of numpy.ndarray
`mesh[0]` contains the 3d coordinates of the vertices
(shape n_vertices, 3)
`mesh[1]` contains, for each triangle, the indices into `mesh[0]` of its
vertices (shape n_triangles, 3)
affine : numpy.ndarray of shape (4, 4)
Affine transformation from image voxels to the vertices' coordinate
space.
segment_half_width : float, optional
Size in mm of the neighbourhood around each vertex in which to draw
samples. Default=3.0.
n_points : int, optional
Number of samples to draw for each vertex. Default=10.
depth : sequence of floats or None, optional
Cortical depth, expressed as a fraction of segment_half_width.
Overrides n_points.
Returns
-------
sample_location_voxel_space : numpy array, shape (n_vertices, n_points, 3)
The locations, in voxel space, from which to draw samples.
First dimension iterates over mesh vertices, second dimension iterates
over the sample points associated to a vertex, third dimension is x, y,
z in voxel space.
"""
vertices, faces = mesh
normals = _vertex_outer_normals(mesh)
if depth is None:
offsets = np.linspace(segment_half_width, -segment_half_width,
n_points)
else:
offsets = -segment_half_width * np.asarray(depth)
sample_locations = vertices[
np.newaxis, :, :] + normals * offsets[:, np.newaxis, np.newaxis]
sample_locations = np.rollaxis(sample_locations, 1)
sample_locations_voxel_space = np.asarray(
resampling.coord_transform(*np.vstack(sample_locations).T,
affine=np.linalg.inv(affine))).T.reshape(
sample_locations.shape)
return sample_locations_voxel_space
def apply_mask_and_get_affinity(seeds,
niimg,
radius,
allow_overlap,
n_jobs=1,
mask_img=None):
import time
start = time.time()
seeds = list(seeds)
affine = niimg.affine
# Compute world coordinates of all in-mask voxels.
mask_img = check_niimg_3d(mask_img)
mask_img = image.resample_img(mask_img,
target_affine=affine,
target_shape=niimg.shape[:3],
interpolation='nearest')
mask, _ = masking._load_mask_img(mask_img)
mask_coords = list(zip(*np.where(mask != 0)))
X = masking._apply_mask_fmri(niimg, mask_img)
# For each seed, get coordinates of nearest voxel
nearests = joblib.Parallel(n_jobs=n_jobs)(
joblib.delayed(seed_nearest)(seed_chunk, affine, mask_coords)
for thread_id, seed_chunk in enumerate(np.array_split(seeds, n_jobs)))
nearests = [i for j in nearests for i in j]
mask_coords = np.asarray(list(zip(*mask_coords)))
mask_coords = coord_transform(mask_coords[0], mask_coords[1],
mask_coords[2], affine)
mask_coords = np.asarray(mask_coords).T
clf = neighbors.NearestNeighbors(radius=radius)
A = clf.fit(mask_coords).radius_neighbors_graph(seeds)
A = A.tolil()
for i, nearest in enumerate(nearests):
if nearest is None:
continue
A[i, nearest] = True
# Include the voxel containing the seed itself if not masked
mask_coords = mask_coords.astype(int).tolist()
for i, seed in enumerate(seeds):
try:
A[i, mask_coords.index(seed)] = True
except ValueError:
# seed is not in the mask
pass
if not allow_overlap:
if np.any(A.sum(axis=0) >= 2):
raise ValueError('Overlap detected between spheres')
return X, A
def demo_plot_roi(**kwargs):
""" Demo plotting an ROI
"""
mni_affine = MNI152TEMPLATE.get_affine()
data = np.zeros((91, 109, 91))
# Color a asymetric rectangle around Broca area:
x, y, z = -52, 10, 22
x_map, y_map, z_map = coord_transform(x, y, z, np.linalg.inv(mni_affine))
data[int(x_map) - 5 : int(x_map) + 5, int(y_map) - 3 : int(y_map) + 3, int(z_map) - 10 : int(z_map) + 10] = 1
img = nibabel.Nifti1Image(data, mni_affine)
return plot_roi(img, title="Broca's area", **kwargs)
def coordinate_label(mni_coord, atlas='aal', thresh=None, ret_proba=False):
if atlas == 'aal':
atl = datasets.fetch_atlas_aal()
atl.prob = False
elif atlas == 'harvard_oxford':
atl = datasets.fetch_atlas_harvard_oxford('cort-prob-2mm')
atl.prob = True
elif atlas == 'destrieux':
atl = datasets.fetch_atlas_destrieux_2009()
atl.indices = atl.labels['index']
atl.labels = atl.labels['name']
atl.prob = False
atl_map = load_img(atl.maps)
atl_aff = atl_map.affine
if atl.prob == True:
atl_labels = atl.labels
if atl.prob == False:
atl_labels = atl.labels
atl_indices = atl.indices
labels_out = list()
for coord in mni_coord:
mat_coord = np.asarray(resampling.coord_transform(
coord[0], coord[1], coord[2], np.linalg.inv(atl_aff)),
dtype=int)
if atl.prob == True and ret_proba == True:
lab_out = get_prob_atlas_label(atl_map,
atl_labels,
mat_coord,
thresh=thresh)
elif atl.prob == True and ret_proba == False:
lab_out, _ = get_prob_atlas_label(atl_map,
atl_labels,
mat_coord,
thresh=thresh)
elif atl.prob == False:
lab_out = get_atlas_label(atl_map, atl_labels, atl_indices,
mat_coord)
labels_out.append(lab_out)
return labels_out
def _get_volume(img,
threshold=0,
atlas=None,
stride=1,
t_start=0,
t_end=-1,
n_t=50,
t_r=None,
marker_size=3,
cmap=cm.cold_hot,
symmetric_cmap=True,
vmax=None,
vmin=None):
connectome = {}
img = check_niimg_4d(img)
t_unit = "" if not t_r else " s"
if not t_r:
t_r = 1
if t_end < 0:
t_end = img.shape[3] + t_end
if not n_t:
n_t = t_end - t_start
t_idx = np.round(np.linspace(t_start, t_end, n_t)).astype(int)
t_labels = [str(t_r * t) + t_unit for t in t_idx]
data = _safe_get_data(img)[::stride, ::stride, ::stride, t_idx]
mask = np.abs(data[:, :, :, 0]) > threshold
i, j, k = mask.nonzero()
x, y, z = coord_transform(i * stride, j * stride, k * stride, img.affine)
for coord, cname in [(x, "x"), (y, "y"), (z, "z")]:
connectome["_con_{}".format(cname)] = encode(
np.asarray(coord, dtype='<f4'))
colors = colorscale(cmap,
data.ravel(),
symmetric_cmap=symmetric_cmap,
vmax=vmax,
vmin=vmin)
if atlas:
atlas = check_niimg_3d(atlas)
atlas_data = _safe_get_data(atlas)[::stride, ::stride, ::stride]
connectome['atlas'] = encode(
np.asarray(atlas_data[i, j, k], dtype='<f4'))
connectome['atlas_nb'] = int(np.max(atlas_data))
connectome['colorscale'] = colors['colors']
connectome['cmin'] = float(colors['vmin'])
connectome['cmax'] = float(colors['vmax'])
connectome['n_time'] = n_t
connectome['t_labels'] = t_labels
values = [
encode(np.asarray(data[i, j, k, t], dtype='<f4'))
for t in range(data.shape[3])
]
connectome['values'] = values
return connectome
def demo_plot_roi(**kwargs):
"""Demo plotting an ROI."""
data = np.zeros((91, 109, 91))
# Color a asymmetric rectangle around Broca area.
x, y, z = -52, 10, 22
x_map, y_map, z_map = coord_transform(x, y, z, np.linalg.inv(MNI_AFFINE))
data[int(x_map) - 5:int(x_map) + 5,
int(y_map) - 3:int(y_map) + 3,
int(z_map) - 10:int(z_map) + 10] = 1
img = Nifti1Image(data, MNI_AFFINE)
return plot_roi(img, title="Broca's area", **kwargs)
def test_plot_roi_contours():
display = plot_roi(None)
data = np.zeros((91, 109, 91))
x, y, z = -52, 10, 22
x_map, y_map, z_map = coord_transform(x, y, z, np.linalg.inv(mni_affine))
data[int(x_map) - 5:int(x_map) + 5,
int(y_map) - 3:int(y_map) + 3,
int(z_map) - 10:int(z_map) + 10] = 1
img = nibabel.Nifti1Image(data, mni_affine)
plot_roi(img, cmap='RdBu', alpha=0.1, view_type='contours', linewidths=2.)
plt.close()
def demo_plot_roi(**kwargs):
""" Demo plotting an ROI
"""
mni_affine = MNI152TEMPLATE.get_affine()
data = np.zeros((91, 109, 91))
# Color a asymetric rectangle around Broca area:
x, y, z = -52, 10, 22
x_map, y_map, z_map = coord_transform(x, y, z, np.linalg.inv(mni_affine))
data[int(x_map) - 5:int(x_map) + 5,
int(y_map) - 3:int(y_map) + 3,
int(z_map) - 10:int(z_map) + 10] = 1
img = nibabel.Nifti1Image(data, mni_affine)
return plot_roi(img, title="Broca's area", **kwargs)
def test_coord_transform_trivial():
rng = np.random.RandomState(42)
sform = np.eye(4)
x = rng.random_sample((10, ))
y = rng.random_sample((10, ))
z = rng.random_sample((10, ))
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x, x_)
np.testing.assert_array_equal(y, y_)
np.testing.assert_array_equal(z, z_)
sform[:, -1] = 1
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the output in case of one item array
x, y, z = x[:1], y[:1], z[:1]
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the output in case of simple items
x, y, z = x[0], y[0], z[0]
x_, y_, z_ = coord_transform(x, y, z, sform)
np.testing.assert_array_equal(x + 1, x_)
np.testing.assert_array_equal(y + 1, y_)
np.testing.assert_array_equal(z + 1, z_)
# Test the outputs have the same shape as the inputs
x = np.ones((3, 2, 4))
y = np.ones((3, 2, 4))
z = np.ones((3, 2, 4))
x_, y_, z_ = coord_transform(x, y, z, sform)
assert x.shape == x_.shape
def fit(self, imgs, y, y_mask=None, groups=None, X=None, A=None):
# check if image is 4D
imgs = check_niimg_4d(imgs)
# Get the seeds
process_mask_img = self.process_mask_img
if self.process_mask_img is None:
process_mask_img = self.mask_img
# Compute world coordinates of the seeds
process_mask, process_mask_affine = masking._load_mask_img(
process_mask_img)
process_mask_coords = np.where(process_mask != 0)
process_mask_coords = coord_transform(process_mask_coords[0],
process_mask_coords[1],
process_mask_coords[2],
process_mask_affine)
process_mask_coords = np.asarray(process_mask_coords).T
import time
start = time.time()
print("GETTING SEARCHLIGHT SPHERES")
X, A = apply_mask_and_get_affinity(process_mask_coords,
imgs,
self.radius,
True,
mask_img=self.mask_img,
n_jobs=self.n_jobs)
self.X = X
self.A = A
self.y = y
self.process_mask = process_mask
elapsed = time.time() - start
print(elapsed)
print("FITTING")
scores = search_light_rsa(X, y, None, A, y_mask, self.n_jobs,
self.verbose)
scores_3D = np.zeros((process_mask.shape) + (len(y), ))
for i in range(len(y)):
scores_3D[process_mask, i] = scores[:, i]
self.scores_ = scores_3D
return self
def fit(self, imgs, y, groups=None):
"""Fit the spatiotemporal searchlight
Parameters
----------
imgs : Niimg-like object
See http://nilearn.github.io/manipulating_images/input_output.html
Use 5D image. [x voxels, y voxels, z voxels, trials, time series of each trials]
y : 1D array-like
Target variable to predict. Must have exactly as many elements as trials in imgs.
groups : array-like, optional
group label for each sample for cross validation. Must have
exactly as many elements as trials in imgs. default None
NOTE: will have no effect for scikit learn < 0.18 (as nilearn says)
"""
# check if image is 5D, simply.
if len(imgs.shape) != 5:
raise ValueError('This SpatioTemporalSearhcLight instance needs 5D image.')
# Get the seeds
process_mask_img = self.mask_img
# Compute world coordinates of the seeds
process_mask, process_mask_affine = masking._load_mask_img(process_mask_img)
process_mask_coords = np.where(process_mask != 0)
process_mask_coords = coord_transform(
process_mask_coords[0], process_mask_coords[1],
process_mask_coords[2], process_mask_affine)
process_mask_coords = np.asarray(process_mask_coords).T
X, A = _apply_mask_and_get_affinity(
process_mask_coords, imgs, self.radius, True,
mask_img=self.mask_img)
# Run Searchlight
scores = self._search_light(X, y, A, groups=groups)
scores_3D = np.zeros(process_mask.shape)
scores_3D[process_mask] = scores
self.scores_ = scores_3D
return self
def test_outlier_cut_coords():
"""Test to plot a subset of a large set of cuts found for a small area."""
bg_img = load_mni152_template()
data = np.zeros((79, 95, 79))
affine = np.array([[-2., 0., 0., 78.],
[0., 2., 0., -112.],
[0., 0., 2., -70.],
[0., 0., 0., 1.]])
# Color a cube around a corner area:
x, y, z = 20, 22, 60
x_map, y_map, z_map = coord_transform(x, y, z, np.linalg.inv(affine))
data[int(x_map) - 1:int(x_map) + 1,
int(y_map) - 1:int(y_map) + 1,
int(z_map) - 1:int(z_map) + 1] = 1
img = Nifti1Image(data, affine)
cuts = find_cut_slices(img, n_cuts=20, direction='z')
plot_stat_map(img, display_mode='z', cut_coords=cuts[-4:],
bg_img=bg_img)
def _get_mask_measures(mask_file):
""" Outputs the mask
Parameters
----------
mask_file : str
Path to the mask image
"""
# TODO: symmetry, length and width
mask_img = nibabel.load(mask_file)
volume = _get_volume(mask_img)
mask_data = mask_img.get_data()
i, j, k = np.where(mask_data != 0)
voxels_coords = np.array(coord_transform(i, j, k, mask_img.affine)).T
x_range, y_range, z_range = voxels_coords.max(axis=0) - \
voxels_coords.min(axis=0)
return x_range, y_range, z_range, volume
def _sample_locations_between_surfaces(
mesh, inner_mesh, affine, n_points=10, depth=None):
outer_vertices, _ = mesh
inner_vertices, _ = inner_mesh
# when we drop support for np 1.5 replace the next 2 lines with
# sample_locations = np.linspace(inner_vertices, outer_vertices, n_points)
if depth is None:
steps = np.linspace(0, 1, n_points)[:, None, None]
else:
steps = np.asarray(depth)[:, None, None]
sample_locations = outer_vertices + steps * (
inner_vertices - outer_vertices)
sample_locations = np.rollaxis(sample_locations, 1)
sample_locations_voxel_space = np.asarray(
resampling.coord_transform(
*np.vstack(sample_locations).T,
affine=np.linalg.inv(affine))).T.reshape(sample_locations.shape)
return sample_locations_voxel_space
def get_seeds(ds, radius):
if check_proximity(ds, radius):
return load_proximity(ds, radius)
# Get the seeds
process_mask_coords = ds.fa.voxel_indices.T
process_mask_coords = coord_transform(
process_mask_coords[0], process_mask_coords[1],
process_mask_coords[2], ds.a.imgaffine)
process_mask_coords = np.asarray(process_mask_coords).T
seeds = process_mask_coords
coords = ds.fa.voxel_indices
logger.info("Building proximity matrix...")
A = _get_affinity(seeds, coords, radius, allow_overlap=True, affine=ds.a.imgaffine)
save_proximity(ds, radius, A)
return A
def test_outlier_cut_coords():
""" Test to plot a subset of a large set of cuts found for a small area."""
bg_img = load_mni152_template()
data = np.zeros((79, 95, 79))
affine = np.array([[ -2., 0., 0., 78.],
[ 0., 2., 0., -112.],
[ 0., 0., 2., -70.],
[ 0., 0., 0., 1.]])
# Color a cube around a corner area:
x, y, z = 20, 22, 60
x_map, y_map, z_map = coord_transform(x, y, z,
np.linalg.inv(affine))
data[int(x_map) - 1:int(x_map) + 1,
int(y_map) - 1:int(y_map) + 1,
int(z_map) - 1:int(z_map) + 1] = 1
img = nibabel.Nifti1Image(data, affine)
cuts = find_cut_slices(img, n_cuts=20, direction='z')
p = plot_stat_map(img, display_mode='z', cut_coords=cuts[-4:],
bg_img=bg_img)
def cluster_stats(stat_img,
mask_img,
threshold,
height_control='fpr',
cluster_th=0,
nulls=None):
"""
Return a list of clusters, each cluster being represented by a
dictionary. Clusters are sorted by descending size order. Within
each cluster, local maxima are sorted by descending statical value
Parameters
----------
stat_img: Niimg-like object,
statsitical image (presumably in z scale)
mask_img: Niimg-like object,
mask image
threshold: float,
cluster forming threshold (either a p-value or z-scale value)
height_control: string
false positive control meaning of cluster forming
threshold: 'fpr'|'fdr'|'bonferroni'|'none'
cluster_th: int or float,
cluster size threshold
nulls: dictionary,
statistics of the null distribution
Notes
-----
If there is no cluster, an empty list is returned
"""
if nulls is None: nulls = {}
# Masking
mask_img, stat_img = check_niimg(mask_img), check_niimg(stat_img)
if not _check_same_fov(mask_img, stat_img):
raise ValueError('mask_img and stat_img do not have the same fov')
mask = mask_img.get_data().astype(np.bool)
affine = mask_img.get_affine()
stat_map = stat_img.get_data() * mask
n_voxels = mask.sum()
# Thresholding
if height_control == 'fpr':
z_th = norm.isf(threshold)
elif height_control == 'fdr':
z_th = fdr_threshold(stat_map[mask], threshold)
elif height_control == 'bonferroni':
z_th = norm.isf(threshold / n_voxels)
else: # Brute-force thresholding
z_th = threshold
p_th = norm.sf(z_th)
# General info
info = {
'n_voxels': n_voxels,
'threshold_z': z_th,
'threshold_p': p_th,
'threshold_pcorr': np.minimum(1, p_th * n_voxels)
}
above_th = stat_map > z_th
above_values = stat_map * above_th
if (above_th == 0).all():
return [], info
# Extract connected components above threshold
labels, n_labels = label(above_th)
# Extract the local maxima anove the threshold
maxima_mask = (above_values == np.maximum(z_th,
maximum_filter(above_values, 3)))
x, y, z = np.array(np.where(maxima_mask))
maxima_coords = np.array(coord_transform(x, y, z, affine)).T
maxima_labels = labels[maxima_mask]
maxima_values = above_values[maxima_mask]
# FDR-corrected p-values
max_fdr_p_values = fdr_p_values(stat_map[mask])[maxima_mask[mask]]
# Default "nulls"
if not 'zmax' in nulls:
nulls['zmax'] = 'bonferroni'
if not 'smax' in nulls:
nulls['smax'] = None
if not 's' in nulls:
nulls['s'] = None
# Make list of clusters, each cluster being a dictionary
clusters = []
for k in range(n_labels):
cluster_size = np.sum(labels == k + 1)
if cluster_size >= cluster_th:
# get the position of the maxima that belong to that cluster
in_cluster = maxima_labels == k + 1
# sort the maxima by decreasing statistical value
max_vals = maxima_values[in_cluster]
sorted_ = max_vals.argsort()[::-1]
# Report significance levels in each cluster
z_score = max_vals[sorted_]
p_values = norm.sf(z_score)
# Voxel-level corrected p-values
fwer_p_value = None
if nulls['zmax'] == 'bonferroni':
fwer_p_value = np.minimum(1, p_values * n_voxels)
elif isinstance(nulls['zmax'], np.ndarray):
fwer_p_value = empirical_p_value(clusters['z_score'],
nulls['zmax'])
# Cluster-level p-values (corrected)
cluster_fwer_p_value = None
if isinstance(nulls['smax'], np.ndarray):
cluster_fwer_p_value = empirical_p_value(
cluster_size, nulls['smax'])
# Cluster-level p-values (uncorrected)
cluster_p_value = None
if isinstance(nulls['s'], np.ndarray):
cluster_p_value = empirical_p_value(cluster_size, nulls['s'])
# write all this into the cluster structure
clusters.append({
'size':
cluster_size,
'maxima':
maxima_coords[in_cluster][sorted_],
'z_score':
z_score,
'fdr_p_value':
max_fdr_p_values[in_cluster][sorted_],
'p_value':
p_values,
'fwer_p_value':
fwer_p_value,
'cluster_fwer_p_value':
cluster_fwer_p_value,
'cluster_p_value':
cluster_p_value
})
# Sort clusters by descending size order
order = np.argsort(-np.array([cluster['size'] for cluster in clusters]))
clusters = [clusters[i] for i in order]
return clusters, info
def find_region_names_using_cut_coords(coords, atlas_img, labels=None):
"""Given list of MNI space coordinates, get names of the brain regions.
Names of the brain regions are returned by getting nearest coordinates
in the given `atlas_img` space iterated over the provided list of
`coords`. These new image coordinates are then used to grab the label
number (int) and name assigned to it. Last, these names are returned.
Parameters
----------
coords : Tuples of coordinates in a list
MNI coordinates.
atlas_img : Nifti-like image
Path to or Nifti-like object. The labels (integers) ordered in
this image should be sequential. Example: [0, 1, 2, 3, 4] but not
[0, 5, 6, 7]. Helps in returning correct names without errors.
labels : str in a list
Names of the brain regions assigned to each label in atlas_img.
NOTE: label with index 0 is assumed as background. Example:
harvard oxford atlas. Hence be removed.
Returns
-------
new_labels : int in a list
Labels in integers generated according to correspondence with
given atlas image and provided coordinates.
names : str in a list
Names of the brain regions generated according to given inputs.
"""
if not isinstance(coords, collections.Iterable):
raise ValueError("coords given must be a list of triplets of "
"coordinates in native space [(1, 2, 3)]. "
"You provided {0}".format(type(coords)))
if isinstance(atlas_img, _basestring):
atlas_img = check_niimg(atlas_img)
affine = get_affine(atlas_img)
atlas_data = _safe_get_data(atlas_img, ensure_finite=True)
check_labels_from_atlas = np.unique(atlas_data)
if labels is not None:
names = []
if not isinstance(labels, collections.Iterable):
labels = np.asarray(labels)
if isinstance(labels, collections.Iterable) and \
isinstance(check_labels_from_atlas, collections.Iterable):
if len(check_labels_from_atlas) != len(labels):
warnings.warn("The number of labels provided does not match "
"with number of unique labels with atlas image.",
stacklevel=2)
coords = list(coords)
nearest_coordinates = []
for sx, sy, sz in coords:
nearest = np.round(coord_transform(sx, sy, sz, np.linalg.inv(affine)))
nearest = nearest.astype(int)
nearest = (nearest[0], nearest[1], nearest[2])
nearest_coordinates.append(nearest)
assert(len(nearest_coordinates) == len(coords))
new_labels = []
for coord_ in nearest_coordinates:
# Grab index of current coordinate
index = atlas_data[coord_]
new_labels.append(index)
if labels is not None:
names.append(labels[index])
if labels is not None:
return new_labels, names
else:
return new_labels
neg_log_pvals_permuted_ols, _, _ = permuted_ols(
tested_var, fmri_masked,
model_intercept=True,
n_perm=5000, # 5,000 for the sake of time. Idealy, this should be 10,000
n_jobs=1) # can be changed to use more CPUs
neg_log_pvals_permuted_ols_unmasked = nifti_masker.inverse_transform(
np.ravel(neg_log_pvals_permuted_ols))
### Visualization #############################################################
from nilearn.plotting import plot_stat_map
# Various plotting parameters
z_slice = 12 # plotted slice
from nilearn.image.resampling import coord_transform
affine = neg_log_pvals_anova_unmasked.get_affine()
_, _, k_slice = coord_transform(0, 0, z_slice,
linalg.inv(affine))
k_slice = round(k_slice)
threshold = - np.log10(0.1) # 10% corrected
vmax = min(np.amax(neg_log_pvals_permuted_ols),
np.amax(neg_log_pvals_anova))
# Plot Anova p-values
fig = plt.figure(figsize=(5, 7), facecolor='k')
display = plot_stat_map(neg_log_pvals_anova_unmasked,
threshold=threshold, cmap=plt.cm.autumn,
display_mode='z', cut_coords=[z_slice],
figure=fig, vmax=vmax, black_bg=True)
neg_log_pvals_anova_data = neg_log_pvals_anova_unmasked.get_data()
def coord_transform_z(z, img):
x, y, z = coord_transform(0, 0, z, img.affine)
return z
def index_to_xy_coord(x, y, z=10):
'''Transforms data index to coordinates of the background + offset'''
coords = coord_transform(x, y, z,
affine=thresholded_score_map_img.get_affine())
return np.array(coords)[np.newaxis, :] + np.array([0, 1, 0])
def coord_transform_x(x, img):
x, y, z = coord_transform(x, 0, 0, img.affine)
return x
def coord_transform_y(y, img):
x, y, z = coord_transform(0, y, 0, img.affine)
return y
def coord_transform_z(z, img):
x, y, z = coord_transform(0, 0, z, img.affine)
return z
def _apply_mask_and_get_affinity(seeds,
niimg,
radius,
allow_overlap,
mask_img=None):
seeds = list(seeds)
aff = niimg.get_affine()
# Compute world coordinates of all in-mask voxels.
if mask_img is not None:
mask_img = check_niimg_3d(mask_img)
mask_img = image.resample_img(mask_img,
target_affine=aff,
target_shape=niimg.shape[:3],
interpolation='nearest')
mask, _ = masking._load_mask_img(mask_img)
mask_coords = list(zip(*np.where(mask != 0)))
# X = masking._apply_mask_fmri(niimg, mask_img)
else:
mask_coords = list(np.ndindex(niimg.shape[:3]))
# For each seed, get coordinates of nearest voxel
nearests = []
for sx, sy, sz in seeds:
nearest = np.round(coord_transform(sx, sy, sz, np.linalg.inv(aff)))
nearest = nearest.astype(int)
nearest = (nearest[0], nearest[1], nearest[2])
try:
nearests.append(mask_coords.index(nearest))
except ValueError:
nearests.append(None)
mask_coords = np.asarray(list(zip(*mask_coords)))
mask_coords = coord_transform(mask_coords[0], mask_coords[1],
mask_coords[2], aff)
mask_coords = np.asarray(mask_coords).T
if (radius is not None
and LooseVersion(sklearn.__version__) < LooseVersion('0.16')):
# Fix for scikit learn versions below 0.16. See
# https://github.com/scikit-learn/scikit-learn/issues/4072
radius += 1e-6
clf = neighbors.NearestNeighbors(radius=radius)
A = clf.fit(mask_coords).radius_neighbors_graph(seeds)
A = A.tolil()
for i, nearest in enumerate(nearests):
if nearest is None:
continue
A[i, nearest] = True
# Include the voxel containing the seed itself if not masked
mask_coords = mask_coords.astype(int).tolist()
for i, seed in enumerate(seeds):
try:
A[i, mask_coords.index(seed)] = True
except ValueError:
# seed is not in the mask
pass
if not allow_overlap:
if np.any(A.sum(axis=0) >= 2):
raise ValueError('Overlap detected between spheres')
return A
def get_clusters_table(stat_img, stat_threshold, cluster_threshold):
"""Creates pandas dataframe with img cluster statistics.
Parameters
----------
stat_img : Niimg-like object,
statistical image (presumably in z scale)
stat_threshold: float, optional
cluster forming threshold (either a p-value or z-scale value)
cluster_threshold : int, optional
cluster size threshold
Returns
-------
Pandas dataframe with img clusters
"""
stat_map = stat_img.get_data()
# If the stat threshold is too high simply return an empty dataframe
if np.sum(stat_map > stat_threshold) == 0:
warn('Attention: No clusters with stat higher than %f' %
stat_threshold)
return pd.DataFrame()
# Extract connected components above threshold
label_map, n_labels = label(stat_map > stat_threshold)
for label_ in range(1, n_labels + 1):
if np.sum(label_map == label_) < cluster_threshold:
stat_map[label_map == label_] = 0
# If the cluster threshold is too high simply return an empty dataframe
# this checks for stats higher than threshold after small clusters
# were removed from stat_map
if np.sum(stat_map > stat_threshold) == 0:
warn('Attention: No clusters with more than %d voxels' %
cluster_threshold)
return pd.DataFrame()
label_map, n_labels = label(stat_map > stat_threshold)
label_map = np.ravel(label_map)
stat_map = np.ravel(stat_map)
peaks = []
max_stat = []
clusters_size = []
coords = []
for label_ in range(1, n_labels + 1):
cluster = stat_map.copy()
cluster[label_map != label_] = 0
peak = np.unravel_index(np.argmax(cluster), stat_img.get_data().shape)
peaks.append(peak)
max_stat.append(np.max(cluster))
clusters_size.append(np.sum(label_map == label_))
x_map, y_map, z_map = peak
mni_coords = np.asarray(
coord_transform(x_map, y_map, z_map,
stat_img.get_affine())).tolist()
mni_coords = [round(x) for x in mni_coords]
coords.append(mni_coords)
vx, vy, vz = zip(*peaks)
x, y, z = zip(*coords)
columns = ['Vx', 'Vy', 'Vz', 'X', 'Y', 'Z', 'Peak stat', 'Cluster size']
clusters_table = pd.DataFrame(list(
zip(vx, vy, vz, x, y, z, max_stat, clusters_size)),
columns=columns)
return clusters_table
def coord_transform_y(y, img):
x, y, z = coord_transform(0, y, 0, img.affine)
return y
def coord_transform_x(x, img):
x, y, z = coord_transform(x, 0, 0, img.affine)
return x
def get_searchlight_neighbours_matrix(mask_file, radius=6):
"""
Parameters
----------
mask_file : string
Path to mask-file.
radius : integer
Searchlight radius in mm.
Returns
-------
A : ndarray, shape(n_voxel, n_voxel)
Affinity matrix. A[i,j]==1 if voxel_i, voxel_j are neighbours
and 0 otherwise
Examples
--------
>>> A = get_searchlight_neighbours_matrix('MNI152_2mm_brain_mask.nii')
>>> A.shape
"""
# heavily borrowed from nilearn: http://nilearn.github.io/
from nilearn import image
from nilearn import masking
from nilearn.image.resampling import coord_transform
from distutils.version import LooseVersion
import sklearn
from sklearn import neighbors
from nilearn._utils.niimg_conversions import check_niimg_3d
def _apply_mask_and_get_affinity(seeds,
niimg,
radius,
allow_overlap,
mask_img=None):
seeds = list(seeds)
aff = niimg.get_affine()
# Compute world coordinates of all in-mask voxels.
if mask_img is not None:
mask_img = check_niimg_3d(mask_img)
mask_img = image.resample_img(mask_img,
target_affine=aff,
target_shape=niimg.shape[:3],
interpolation='nearest')
mask, _ = masking._load_mask_img(mask_img)
mask_coords = list(zip(*np.where(mask != 0)))
# X = masking._apply_mask_fmri(niimg, mask_img)
else:
mask_coords = list(np.ndindex(niimg.shape[:3]))
# For each seed, get coordinates of nearest voxel
nearests = []
for sx, sy, sz in seeds:
nearest = np.round(coord_transform(sx, sy, sz, np.linalg.inv(aff)))
nearest = nearest.astype(int)
nearest = (nearest[0], nearest[1], nearest[2])
try:
nearests.append(mask_coords.index(nearest))
except ValueError:
nearests.append(None)
mask_coords = np.asarray(list(zip(*mask_coords)))
mask_coords = coord_transform(mask_coords[0], mask_coords[1],
mask_coords[2], aff)
mask_coords = np.asarray(mask_coords).T
if (radius is not None
and LooseVersion(sklearn.__version__) < LooseVersion('0.16')):
# Fix for scikit learn versions below 0.16. See
# https://github.com/scikit-learn/scikit-learn/issues/4072
radius += 1e-6
clf = neighbors.NearestNeighbors(radius=radius)
A = clf.fit(mask_coords).radius_neighbors_graph(seeds)
A = A.tolil()
for i, nearest in enumerate(nearests):
if nearest is None:
continue
A[i, nearest] = True
# Include the voxel containing the seed itself if not masked
mask_coords = mask_coords.astype(int).tolist()
for i, seed in enumerate(seeds):
try:
A[i, mask_coords.index(seed)] = True
except ValueError:
# seed is not in the mask
pass
if not allow_overlap:
if np.any(A.sum(axis=0) >= 2):
raise ValueError('Overlap detected between spheres')
return A
process_mask_img = nib.load(mask_file)
# Compute world coordinates of the seeds
process_mask, process_mask_affine = masking._load_mask_img(
process_mask_img)
process_mask_coords = np.where(process_mask != 0)
process_mask_coords = coord_transform(process_mask_coords[0],
process_mask_coords[1],
process_mask_coords[2],
process_mask_affine)
process_mask_coords = np.asarray(process_mask_coords).T
A = _apply_mask_and_get_affinity(process_mask_coords,
process_mask_img,
radius,
True,
mask_img=process_mask_img)
return A # .toarray().astype('bool')
def cluster_stats(stat_img, mask_img, threshold, height_control='fpr',
cluster_th=0, nulls=None):
"""
Return a list of clusters, each cluster being represented by a
dictionary. Clusters are sorted by descending size order. Within
each cluster, local maxima are sorted by descending statical value
Parameters
----------
stat_img: Niimg-like object,
statsitical image (presumably in z scale)
mask_img: Niimg-like object,
mask image
threshold: float,
cluster forming threshold (either a p-value or z-scale value)
height_control: string
false positive control meaning of cluster forming
threshold: 'fpr'|'fdr'|'bonferroni'|'none'
cluster_th: int or float,
cluster size threshold
nulls: dictionary,
statistics of the null distribution
Notes
-----
If there is no cluster, an empty list is returned
"""
if nulls is None: nulls = {}
# Masking
mask_img, stat_img = check_niimg(mask_img), check_niimg(stat_img)
if not _check_same_fov(mask_img, stat_img):
raise ValueError('mask_img and stat_img do not have the same fov')
mask = mask_img.get_data().astype(np.bool)
affine = mask_img.get_affine()
stat_map = stat_img.get_data() * mask
n_voxels = mask.sum()
# Thresholding
if height_control == 'fpr':
z_th = norm.isf(threshold)
elif height_control == 'fdr':
z_th = fdr_threshold(stat_map[mask], threshold)
elif height_control == 'bonferroni':
z_th = norm.isf(threshold / n_voxels)
else: # Brute-force thresholding
z_th = threshold
p_th = norm.sf(z_th)
# General info
info = {'n_voxels': n_voxels,
'threshold_z': z_th,
'threshold_p': p_th,
'threshold_pcorr': np.minimum(1, p_th * n_voxels)}
above_th = stat_map > z_th
above_values = stat_map * above_th
if (above_th == 0).all():
return [], info
# Extract connected components above threshold
labels, n_labels = label(above_th)
# Extract the local maxima anove the threshold
maxima_mask = (above_values ==
np.maximum(z_th, maximum_filter(above_values, 3)))
x, y, z = np.array(np.where(maxima_mask))
maxima_coords = np.array(coord_transform(x, y, z, affine)).T
maxima_labels = labels[maxima_mask]
maxima_values = above_values[maxima_mask]
# FDR-corrected p-values
max_fdr_p_values = fdr_p_values(stat_map[mask])[maxima_mask[mask]]
# Default "nulls"
if not 'zmax' in nulls:
nulls['zmax'] = 'bonferroni'
if not 'smax' in nulls:
nulls['smax'] = None
if not 's' in nulls:
nulls['s'] = None
# Make list of clusters, each cluster being a dictionary
clusters = []
for k in range(n_labels):
cluster_size = np.sum(labels == k + 1)
if cluster_size >= cluster_th:
# get the position of the maxima that belong to that cluster
in_cluster = maxima_labels == k + 1
# sort the maxima by decreasing statistical value
max_vals = maxima_values[in_cluster]
sorted_ = max_vals.argsort()[::-1]
# Report significance levels in each cluster
z_score = max_vals[sorted_]
p_values = norm.sf(z_score)
# Voxel-level corrected p-values
fwer_p_value = None
if nulls['zmax'] == 'bonferroni':
fwer_p_value = np.minimum(1, p_values * n_voxels)
elif isinstance(nulls['zmax'], np.ndarray):
fwer_p_value = empirical_p_value(
clusters['z_score'], nulls['zmax'])
# Cluster-level p-values (corrected)
cluster_fwer_p_value = None
if isinstance(nulls['smax'], np.ndarray):
cluster_fwer_p_value = empirical_p_value(
cluster_size, nulls['smax'])
# Cluster-level p-values (uncorrected)
cluster_p_value = None
if isinstance(nulls['s'], np.ndarray):
cluster_p_value = empirical_p_value(
cluster_size, nulls['s'])
# write all this into the cluster structure
clusters.append({
'size': cluster_size,
'maxima': maxima_coords[in_cluster][sorted_],
'z_score': z_score,
'fdr_p_value': max_fdr_p_values[in_cluster][sorted_],
'p_value': p_values,
'fwer_p_value': fwer_p_value,
'cluster_fwer_p_value': cluster_fwer_p_value,
'cluster_p_value': cluster_p_value
})
# Sort clusters by descending size order
order = np.argsort(- np.array([cluster['size'] for cluster in clusters]))
clusters = [clusters[i] for i in order]
return clusters, info
def get_clusters_table(stat_img, stat_threshold, cluster_threshold=None,
min_distance=8.):
"""Creates pandas dataframe with img cluster statistics.
Parameters
----------
stat_img : Niimg-like object,
Statistical image (presumably in z- or p-scale).
stat_threshold: `float`
Cluster forming threshold in same scale as `stat_img` (either a
p-value or z-scale value).
cluster_threshold : `int` or `None`, optional
Cluster size threshold, in voxels.
min_distance: `float`, optional
Minimum distance between subpeaks in mm. Default is 8 mm.
Returns
-------
df : `pandas.DataFrame`
Table with peaks and subpeaks from thresholded `stat_img`. For binary
clusters (clusters with >1 voxel containing only one value), the table
reports the center of mass of the cluster, rather than any peaks/subpeaks.
"""
cols = ['Cluster ID', 'X', 'Y', 'Z', 'Peak Stat', 'Cluster Size (mm3)']
stat_map = stat_img.get_data()
conn_mat = np.zeros((3, 3, 3), int) # 6-connectivity, aka NN1 or "faces"
conn_mat[1, 1, :] = 1
conn_mat[1, :, 1] = 1
conn_mat[:, 1, 1] = 1
voxel_size = np.prod(stat_img.header.get_zooms())
# Binarize using CDT
binarized = stat_map > stat_threshold
binarized = binarized.astype(int)
# If the stat threshold is too high simply return an empty dataframe
if np.sum(binarized) == 0:
warnings.warn('Attention: No clusters with stat higher than %f' %
stat_threshold)
return pd.DataFrame(columns=cols)
# Extract connected components above cluster size threshold
label_map = ndimage.measurements.label(binarized, conn_mat)[0]
clust_ids = sorted(list(np.unique(label_map)[1:]))
for c_val in clust_ids:
if cluster_threshold is not None and np.sum(
label_map == c_val) < cluster_threshold:
stat_map[label_map == c_val] = 0
binarized[label_map == c_val] = 0
# If the cluster threshold is too high simply return an empty dataframe
# this checks for stats higher than threshold after small clusters
# were removed from stat_map
if np.sum(stat_map > stat_threshold) == 0:
warnings.warn('Attention: No clusters with more than %d voxels' %
cluster_threshold)
return pd.DataFrame(columns=cols)
# Now re-label and create table
label_map = ndimage.measurements.label(binarized, conn_mat)[0]
clust_ids = sorted(list(np.unique(label_map)[1:]))
peak_vals = np.array(
[np.max(stat_map * (label_map == c)) for c in clust_ids])
clust_ids = [clust_ids[c] for c in
(-peak_vals).argsort()] # Sort by descending max value
rows = []
for c_id, c_val in enumerate(clust_ids):
cluster_mask = label_map == c_val
masked_data = stat_map * cluster_mask
cluster_size_mm = int(np.sum(cluster_mask) * voxel_size)
# Get peaks, subpeaks and associated statistics
subpeak_ijk, subpeak_vals = _local_max(masked_data, stat_img.affine,
min_distance=min_distance)
subpeak_xyz = np.asarray(coord_transform(subpeak_ijk[:, 0],
subpeak_ijk[:, 1],
subpeak_ijk[:, 2],
stat_img.affine)).tolist()
subpeak_xyz = np.array(subpeak_xyz).T
# Only report peak and, at most, top 3 subpeaks.
n_subpeaks = np.min((len(subpeak_vals), 4))
for subpeak in range(n_subpeaks):
if subpeak == 0:
row = [c_id + 1, subpeak_xyz[subpeak, 0],
subpeak_xyz[subpeak, 1], subpeak_xyz[subpeak, 2],
subpeak_vals[subpeak], cluster_size_mm]
else:
# Subpeak naming convention is cluster num + letter (1a, 1b, etc.)
sp_id = '{0}{1}'.format(c_id + 1, ascii_lowercase[subpeak - 1])
row = [sp_id, subpeak_xyz[subpeak, 0], subpeak_xyz[subpeak, 1],
subpeak_xyz[subpeak, 2], subpeak_vals[subpeak], '']
rows += [row]
df = pd.DataFrame(columns=cols, data=rows)
return df
def compute_spheres_values(self, imgs):
start_t = time.time()
# Force to get a list of imgs even if only one is given
imgs_to_check = [imgs] if not isinstance(imgs, list) else imgs
# Load Nifti images
ref_shape = imgs_to_check[0].dataobj.shape
ref_affine = imgs_to_check[0].affine
imgs = []
for img in imgs_to_check:
# check if image is 4D
imgs.append(check_niimg_4d(img))
# Check that all images have same number of volumes
if ref_shape != img.dataobj.shape:
raise ValueError("All fMRI image must have same shape")
if np.array_equal(ref_affine, img.affine):
warnings.warn("fMRI images do not have same affine")
self.ref_img = imgs[0]
# Compute world coordinates of the seeds
process_mask_img = check_niimg_3d(self.process_mask_img)
process_mask_img = image.resample_to_img(
process_mask_img, imgs[0], interpolation='nearest'
)
self.process_mask_img = process_mask_img
process_mask, process_mask_affine = masking._load_mask_img(
process_mask_img
)
process_mask_coords = np.where(process_mask != 0)
self.vx_mask_coords = process_mask_coords
process_mask_coords = coord_transform(
process_mask_coords[0], process_mask_coords[1],
process_mask_coords[2], process_mask_affine)
process_mask_coords = np.asarray(process_mask_coords).T
if self.verbose:
print("{} seeds found in the mask".format(len(process_mask_coords)))
# Compute spheres
_, A = _apply_mask_and_get_affinity(
process_mask_coords, imgs[0], self.radius, True,
mask_img=self.mask_img
)
# Number of runs: 1 4D fMRI image / run
n_runs = len(imgs)
# Number of spheres (or seed voxels)
n_spheres = A.shape[0]
# Number of volumes in each 4D fMRI image
n_conditions = imgs[0].dataobj.shape[3]
mask_img = check_niimg_3d(self.mask_img)
mask_img = image.resample_img(
mask_img, target_affine=imgs[0].affine,
target_shape=imgs[0].shape[:3], interpolation='nearest'
)
masked_imgs_data = []
for i_run, img in enumerate(imgs):
masked_imgs_data.append(masking._apply_mask_fmri(img, mask_img))
# Extract data of each sphere
# X will be #spheres x #run x #conditions x #values
X = []
for i_sph in range(n_spheres):
# Indexes of all voxels included in the current sphere
sph_indexes = A.rows[i_sph]
if len(sph_indexes) == 0:
# Append when no data are available around the process voxel
X.append(np.full((n_runs, n_conditions, 1), 0))
print("Empty sphere")
else:
# Number of voxel in the current sphere
n_values = len(sph_indexes)
sub_X = np.empty((n_runs, n_conditions, n_values), dtype=object)
for i_run, img in enumerate(imgs):
for i_cond in range(n_conditions):
sub_X[i_run, i_cond] = masked_imgs_data[i_run][i_cond][
sph_indexes]
X.append(sub_X)
if self.verbose:
dt = time.time() - start_t
print("Elapsed time to extract spheres values: {:.01f}s".format(dt))
self.spheres_values = X