def test_partitionmapper():
ds = give_data()
oep = OddEvenPartitioner()
parts = list(oep.generate(ds))
assert_equal(len(parts), 2)
for i, p in enumerate(parts):
assert_array_equal(p.sa['partitions'].unique, [1, 2])
assert_equal(p.a.partitions_set, i)
assert_equal(len(p), len(ds))
def test_partitionmapper():
ds = give_data()
oep = OddEvenPartitioner()
parts = list(oep.generate(ds))
assert_equal(len(parts), 2)
for i, p in enumerate(parts):
assert_array_equal(p.sa['partitions'].unique, [1, 2])
assert_equal(p.a.partitions_set, i)
assert_equal(len(p), len(ds))
def test_searchlight_errors_per_trial():
# To make sure that searchlight can return error/accuracy per trial
from mvpa2.clfs.gnb import GNB
from mvpa2.generators.partition import OddEvenPartitioner
from mvpa2.measures.base import CrossValidation
from mvpa2.measures.searchlight import sphere_searchlight
from mvpa2.measures.gnbsearchlight import sphere_gnbsearchlight
from mvpa2.testing.datasets import datasets
from mvpa2.misc.errorfx import prediction_target_matches
dataset = datasets['3dsmall'].copy()
# randomly permute samples so we break any random correspondence
# to strengthen tests below
sample_idx = np.arange(len(dataset))
dataset = dataset[np.random.permutation(sample_idx)]
dataset.sa.targets = ['L%d' % l for l in dataset.sa.targets]
dataset.fa['voxel_indices'] = dataset.fa.myspace
sample_clf = GNB() # fast and deterministic
part = OddEvenPartitioner()
# only do partial to save time
cv = CrossValidation(sample_clf, part, errorfx=None) #prediction_target_matches)
# Just to compare error
cv_error = CrossValidation(sample_clf, part)
# Large searchlight radius so we get entire ROI, 2 centers just to make sure
# that all stacking works correctly
sl = sphere_searchlight(cv, radius=10, center_ids=[0, 1])
results = sl(dataset)
sl_gnb = sphere_gnbsearchlight(sample_clf, part, radius=10, errorfx=None,
center_ids=[0, 1])
results_gnbsl = sl_gnb(dataset)
# inspect both results
# verify that partitioning was done correctly
partitions = list(part.generate(dataset))
for res in (results, results_gnbsl):
assert('targets' in res.sa.keys()) # should carry targets
assert('cvfolds' in res.sa.keys()) # should carry cvfolds
for ipart in xrange(len(partitions)):
assert_array_equal(dataset[partitions[ipart].sa.partitions == 2].targets,
res.sa.targets[res.sa.cvfolds == ipart])
assert_datasets_equal(results, results_gnbsl)
# one "accuracy" per each trial
assert_equal(results.shape, (len(dataset), 2))
# with accuracies the same in both searchlights since the same
# features were to be selected in both cases due too large radii
errors_dataset = cv(dataset)
assert_array_equal(errors_dataset.samples[:, 0], results.samples[:, 0])
assert_array_equal(errors_dataset.samples[:, 0], results.samples[:, 1])
# and error matching (up to precision) the one if we run with default error function
assert_array_almost_equal(np.mean(results.targets[:, None] != results.samples, axis=0)[0],
np.mean(cv_error(dataset)))
def test_regression_as_classifier(self, regr):
"""Basic tests of metaclass for using regressions as classifiers
"""
for dsname in 'uni2small', 'uni4small':
ds = datasets[dsname]
clf = RegressionAsClassifier(regr, enable_ca=['distances'])
cv = CrossValidation(clf,
OddEvenPartitioner(),
postproc=mean_sample(),
enable_ca=['stats', 'training_stats'])
error = cv(ds).samples.squeeze()
nlabels = len(ds.uniquetargets)
if nlabels == 2 \
and cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(error < 0.3,
msg="Got error %.2f on %s dataset" %
(error, dsname))
# Check if does not puke on repr and str
self.assertTrue(str(clf) != "")
self.assertTrue(repr(clf) != "")
self.assertEqual(clf.ca.distances.shape,
(ds.nsamples / 2, nlabels))
def test_null_dist_prob(self, l_clf):
train = datasets['uni2medium']
num_perm = 10
permutator = AttributePermutator('targets',
count=num_perm,
limit='chunks')
# define class to estimate NULL distribution of errors
# use left tail of the distribution since we use MeanMatchFx as error
# function and lower is better
terr = TransferMeasure(l_clf,
Repeater(count=2),
postproc=BinaryFxNode(mean_mismatch_error,
'targets'),
null_dist=MCNullDist(permutator, tail='left'))
# check reasonable error range
err = terr(train)
self.assertTrue(np.mean(err) < 0.4)
# Lets do the same for CVTE
cvte = CrossValidation(l_clf,
OddEvenPartitioner(),
null_dist=MCNullDist(permutator,
tail='left',
enable_ca=['dist_samples'
]),
postproc=mean_sample())
cv_err = cvte(train)
# check that the result is highly significant since we know that the
# data has signal
null_prob = np.asscalar(terr.ca.null_prob)
if cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(
null_prob <= 0.1,
msg="Failed to check that the result is highly significant "
"(got %f) since we know that the data has signal" % null_prob)
self.assertTrue(
np.asscalar(cvte.ca.null_prob) <= 0.1,
msg="Failed to check that the result is highly significant "
"(got p(cvte)=%f) since we know that the data has signal" %
np.asscalar(cvte.ca.null_prob))
# we should be able to access the actual samples of the distribution
# yoh: why it is 3D really?
# mih: because these are the distribution samples for the ONE error
# collapsed into ONE value across all folds. It will also be
# 3d if the return value of the measure isn't a scalar and it is
# not collapsed across folds. it simply corresponds to the shape
# of the output dataset of the respective measure (+1 axis)
# Some permutations could have been skipped since classifier failed
# to train due to degenerate situation etc, thus accounting for them
self.assertEqual(cvte.null_dist.ca.dist_samples.shape[2],
num_perm - cvte.null_dist.ca.skipped)
def test_nblocks(self):
skip_if_no_external('pprocess')
# just a basic test to see that we are getting the same
# results with different nblocks
ds = datasets['3dsmall'].copy(deep=True)[:, :13]
ds.fa['voxel_indices'] = ds.fa.myspace
cv = CrossValidation(GNB(), OddEvenPartitioner())
res1 = sphere_searchlight(cv, radius=1, nproc=2)(ds)
res2 = sphere_searchlight(cv, radius=1, nproc=2, nblocks=5)(ds)
assert_array_equal(res1, res2)
def test_regression_with_additional_sa(self):
regr = regrswh[:][0]
ds = datasets['3dsmall'].copy()
ds.fa['voxel_indices'] = ds.fa.myspace
# Create a new sample attribute which will be used along with
# every searchlight
ds.sa['beh'] = np.random.normal(size=(ds.nsamples, 2))
# and now for fun -- lets create custom linar regression
# targets out of some random feature and beh linearly combined
rfeature = np.random.randint(ds.nfeatures)
ds.sa.targets = np.dot(
np.hstack((ds.sa.beh, ds.samples[:, rfeature:rfeature + 1])),
np.array([0.3, 0.2, 0.3]))
class CrossValidationWithBeh(CrossValidation):
"""An adapter for regular CV which would hstack
sa.beh to the searchlighting ds"""
def _call(self, ds):
return CrossValidation._call(
self, Dataset(np.hstack((ds, ds.sa.beh)), sa=ds.sa))
cvbeh = CrossValidationWithBeh(regr,
OddEvenPartitioner(),
errorfx=corr_error)
# regular cv
cv = CrossValidation(regr, OddEvenPartitioner(), errorfx=corr_error)
slbeh = sphere_searchlight(cvbeh, radius=1)
slmapbeh = slbeh(ds)
sl = sphere_searchlight(cv, radius=1)
slmap = sl(ds)
assert_equal(slmap.shape, (2, ds.nfeatures))
# SL which had access to beh should have got for sure better
# results especially in the vicinity of the chosen feature...
features = sl.queryengine.query_byid(rfeature)
assert_array_lequal(slmapbeh.samples[:, features],
slmap.samples[:, features])
def test_values(self, clf):
if isinstance(clf, MulticlassClassifier):
# TODO: handle those values correctly
return
ds = datasets['uni2small']
clf.ca.change_temporarily(enable_ca = ['estimates'])
cv = CrossValidation(clf, OddEvenPartitioner(),
enable_ca=['stats', 'training_stats'])
_ = cv(ds)
#print clf.descr, clf.values[0]
# basic test either we get 1 set of values per each sample
self.assertEqual(len(clf.ca.estimates), ds.nsamples/2)
clf.ca.reset_changed_temporarily()
def test_auc(self, clf):
"""Test AUC computation
"""
if isinstance(clf, MulticlassClassifier):
raise SkipTest, \
"TODO: handle values correctly in MulticlassClassifier"
clf.ca.change_temporarily(enable_ca=['estimates'])
if 'qda' in clf.__tags__:
# for reliable estimation of covariances, need sufficient
# sample size
ds_size = 'large'
else:
ds_size = 'small'
# uni2 dataset with reordered labels
ds2 = datasets['uni2' + ds_size].copy()
# revert labels
ds2.sa['targets'].value = ds2.targets[::-1].copy()
# same with uni3
ds3 = datasets['uni3' + ds_size].copy()
ul = ds3.sa['targets'].unique
nl = ds3.targets.copy()
for l in xrange(3):
nl[ds3.targets == ul[l]] = ul[(l + 1) % 3]
ds3.sa.targets = nl
for ds in [
datasets['uni2' + ds_size], ds2, datasets['uni3' + ds_size],
ds3
]:
cv = CrossValidation(clf,
OddEvenPartitioner(),
enable_ca=['stats', 'training_stats'])
cverror = cv(ds)
stats = cv.ca.stats.stats
Nlabels = len(ds.uniquetargets)
# so we at least do slightly above chance
# But LARS manages to screw up there as well ATM from time to time, so making
# its testing labile
if (('lars' in clf.__tags__) and cfg.getboolean('tests', 'labile', default='yes')) \
or (not 'lars' in clf.__tags__):
self.assertTrue(stats['ACC'] > 1.2 / Nlabels)
auc = stats['AUC']
if (Nlabels == 2) or (Nlabels > 2 and auc[0] is not np.nan):
mauc = np.min(stats['AUC'])
if cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(
mauc > 0.55,
msg='All AUCs must be above chance. Got minimal '
'AUC=%.2g among %s' % (mauc, stats['AUC']))
clf.ca.reset_changed_temporarily()
def test_single_class(self, clf):
"""Test if binary and multiclass can handle single class training/testing
"""
ds = datasets['uni2small']
ds = ds[ds.sa.targets == 'L0'] # only 1 label
assert(ds.sa['targets'].unique == ['L0'])
ds_ = list(OddEvenPartitioner().generate(ds))[0]
# Here is our "nice" 0.6 substitute for TransferError:
trerr = TransferMeasure(clf, Splitter('train'),
postproc=BinaryFxNode(mean_mismatch_error,
'targets'))
try:
err = np.asscalar(trerr(ds_))
except Exception, e:
self.fail(str(e))
def test_tree_classifier(self):
"""Basic tests for TreeClassifier
"""
ds = datasets['uni4medium']
# make it simple of the beast -- take only informative ones
# because classifiers for the tree are selected randomly, so
# performance varies a lot and we just need to check on
# correct operation
ds = ds[:, ds.fa.nonbogus_targets != [None]]
clfs = clfswh['binary'] # pool of classifiers
# Lets permute so each time we try some different combination
# of the classifiers but exclude those operating on %s of
# features since we might not have enough for that
clfs = [
clfs[i] for i in np.random.permutation(len(clfs))
if not '%' in str(clfs[i])
]
# NB: It is necessary that the same classifier was not used at
# different nodes, since it would be re-trained for a new set
# of targets, thus leading to incorrect behavior/high error.
#
# Clone only those few leading ones which we will use
# throughout the test
clfs = [clf.clone() for clf in clfs[:4]]
# Test conflicting definition
tclf = TreeClassifier(clfs[0], {
'L0+2': (('L0', 'L2'), clfs[1]),
'L2+3': (('L2', 'L3'), clfs[2])
})
self.assertRaises(ValueError, tclf.train, ds)
"""Should raise exception since label 2 is in both"""
# Test insufficient definition
tclf = TreeClassifier(clfs[0], {
'L0+5': (('L0', 'L5'), clfs[1]),
'L2+3': (('L2', 'L3'), clfs[2])
})
self.assertRaises(ValueError, tclf.train, ds)
"""Should raise exception since no group for L1"""
# proper definition now
tclf = TreeClassifier(clfs[0], {
'L0+1': (('L0', 'L1'), clfs[1]),
'L2+3': (('L2', 'L3'), clfs[2])
})
# Lets test train/test cycle using CVTE
cv = CrossValidation(tclf,
OddEvenPartitioner(),
postproc=mean_sample(),
enable_ca=['stats', 'training_stats'])
cverror = cv(ds).samples.squeeze()
try:
rtclf = repr(tclf)
except:
self.fail(msg="Could not obtain repr for TreeClassifier")
# Test accessibility of .clfs
self.assertTrue(tclf.clfs['L0+1'] is clfs[1])
self.assertTrue(tclf.clfs['L2+3'] is clfs[2])
cvtrc = cv.ca.training_stats
cvtc = cv.ca.stats
if cfg.getboolean('tests', 'labile', default='yes'):
# just a dummy check to make sure everything is working
self.assertTrue(cvtrc != cvtc)
self.assertTrue(cverror < 0.3,
msg="Got too high error = %s using %s" %
(cverror, tclf))
# Test trailing nodes with no classifier
# That is why we use separate pool of classifiers here
# (that is probably old/not-needed since switched to use clones)
clfs_mc = clfswh['multiclass'] # pool of classifiers
clfs_mc = [
clfs_mc[i] for i in np.random.permutation(len(clfs_mc))
if not '%' in str(clfs_mc[i])
]
clfs_mc = [clf.clone() for clf in clfs_mc[:4]] # and clones again
tclf = TreeClassifier(clfs_mc[0], {
'L0': (('L0', ), None),
'L1+2+3': (('L1', 'L2', 'L3'), clfs_mc[1])
})
cv = CrossValidation(tclf,
OddEvenPartitioner(),
postproc=mean_sample(),
enable_ca=['stats', 'training_stats'])
cverror = np.asscalar(cv(ds))
if cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(cverror < 0.3,
msg="Got too high error = %s using %s" %
(cverror, tclf))
def generate_testing_datasets(specs):
# Lets permute upon each invocation of test, so we could possibly
# trigger some funny cases
nonbogus_pool = np.random.permutation([0, 1, 3, 5])
datasets = {}
# use a partitioner to flag odd/even samples as training and test
ttp = OddEvenPartitioner(space='train', count=1)
for kind, spec in specs.iteritems():
# set of univariate datasets
for nlabels in [ 2, 3, 4 ]:
basename = 'uni%d%s' % (nlabels, kind)
nonbogus_features = nonbogus_pool[:nlabels]
dataset = normal_feature_dataset(
nlabels=nlabels,
nonbogus_features=nonbogus_features,
**spec)
# full dataset
datasets[basename] = list(ttp.generate(dataset))[0]
# sample 3D
total = 2*spec['perlabel']
nchunks = spec['nchunks']
data = np.random.standard_normal(( total, 3, 6, 6 ))
labels = np.concatenate( ( np.repeat( 0, spec['perlabel'] ),
np.repeat( 1, spec['perlabel'] ) ) )
data[:, 1, 0, 0] += 2*labels # add some signal
chunks = np.asarray(range(nchunks)*(total/nchunks))
mask = np.ones((3, 6, 6), dtype='bool')
mask[0, 0, 0] = 0
mask[1, 3, 2] = 0
ds = Dataset.from_wizard(samples=data, targets=labels, chunks=chunks,
mask=mask, space='myspace')
# and to stress tests on manipulating sa/fa possibly containing
# attributes of dtype object
ds.sa['test_object'] = [['a'], [1, 2]] * (ds.nsamples/2)
datasets['3d%s' % kind] = ds
# some additional datasets
datasets['dumb2'] = dumb_feature_binary_dataset()
datasets['dumb'] = dumb_feature_dataset()
# dataset with few invariant features
_dsinv = dumb_feature_dataset()
_dsinv.samples = np.hstack((_dsinv.samples,
np.zeros((_dsinv.nsamples, 1)),
np.ones((_dsinv.nsamples, 1))))
datasets['dumbinv'] = _dsinv
# Datasets for regressions testing
datasets['sin_modulated'] = list(ttp.generate(multiple_chunks(sin_modulated, 4, 30, 1)))[0]
# use the same full for training
datasets['sin_modulated_train'] = datasets['sin_modulated']
datasets['sin_modulated_test'] = sin_modulated(30, 1, flat=True)
# simple signal for linear regressors
datasets['chirp_linear'] = multiple_chunks(chirp_linear, 6, 50, 10, 2, 0.3, 0.1)
datasets['chirp_linear_test'] = chirp_linear(20, 5, 2, 0.4, 0.1)
datasets['wr1996'] = multiple_chunks(wr1996, 4, 50)
datasets['wr1996_test'] = wr1996(50)
datasets['hollow'] = Dataset(HollowSamples((40,20)),
sa={'targets': np.tile(['one', 'two'], 20)})
return datasets
def test_multiclass_pairs_svm_searchlight():
from mvpa2.measures.searchlight import sphere_searchlight
import mvpa2.clfs.meta
#reload(mvpa2.clfs.meta)
from mvpa2.clfs.meta import MulticlassClassifier
from mvpa2.datasets import Dataset
from mvpa2.clfs.svm import LinearCSVMC
#import mvpa2.testing.datasets
#reload(mvpa2.testing.datasets)
from mvpa2.testing.datasets import datasets
from mvpa2.generators.partition import NFoldPartitioner, OddEvenPartitioner
from mvpa2.measures.base import CrossValidation
from mvpa2.testing import ok_, assert_equal, assert_array_equal
from mvpa2.sandbox.multiclass import get_pairwise_accuracies
# Some parameters used in the test below
nproc = 1 + int(mvpa2.externals.exists('pprocess'))
ntargets = 4 # number of targets
npairs = ntargets*(ntargets-1)/2
center_ids = [35, 55, 1]
ds = datasets['3dsmall'].copy()
# redefine C,T so we have a multiclass task
nsamples = len(ds)
ds.sa.targets = range(ntargets) * (nsamples//ntargets)
ds.sa.chunks = np.arange(nsamples) // ntargets
# and add some obvious signal where it is due
ds.samples[:, 55] += 15*ds.sa.targets # for all 4 targets
ds.samples[:, 35] += 15*(ds.sa.targets % 2) # so we have conflicting labels
# while 35 would still be just for 2 categories which would conflict
mclf = MulticlassClassifier(LinearCSVMC(),
pass_attr=['sa.chunks', 'ca.raw_predictions_ds'],
enable_ca=['raw_predictions_ds'])
label_pairs = mclf._get_binary_pairs(ds)
def place_sa_as_samples(ds):
# add a degenerate dimension for the hstacking in the searchlight
ds.samples = ds.sa.raw_predictions_ds[:, None]
ds.sa.pop('raw_predictions_ds') # no need to drag the copy
return ds
mcv = CrossValidation(mclf, OddEvenPartitioner(), errorfx=None,
postproc=place_sa_as_samples)
sl = sphere_searchlight(mcv, nproc=nproc, radius=2, space='myspace',
center_ids=center_ids)
slmap = sl(ds)
ok_('chunks' in slmap.sa)
ok_('cvfolds' in slmap.sa)
ok_('targets' in slmap.sa)
# so for each SL we got all pairwise tests
assert_equal(slmap.shape, (nsamples, len(center_ids), npairs))
assert_array_equal(np.unique(slmap.sa.cvfolds), [0, 1])
# Verify that we got right labels in each 'pair'
# all searchlights should have the same set of labels for a given
# pair of targets
label_pairs_ = np.apply_along_axis(
np.unique, 0,
## reshape slmap so we have only simple pairs in the columns
np.reshape(slmap, (-1, npairs))).T
# need to prep that list of pairs obtained from MulticlassClassifier
# and since it is 1-vs-1, they all should be just pairs of lists of
# 1 element so should work
assert_equal(len(label_pairs_), npairs)
assert_array_equal(np.squeeze(np.array(label_pairs)), label_pairs_)
assert_equal(label_pairs_.shape, (npairs, 2)) # for this particular case
out = get_pairwise_accuracies(slmap)
out123 = get_pairwise_accuracies(slmap, select=[1, 2, 3])
assert_array_equal(np.unique(out123.T), np.arange(1, 4)) # so we got at least correct targets
# test that we extracted correct accuracies
# First 3 in out.T should have category 0, so skip them and compare otherwise
assert_array_equal(out.samples[3:], out123.samples)
ok_(np.all(out.samples[:, 1] == 1.), "This was with super-strong result")
def test_voxel_selection(self):
'''Compare surface and volume based searchlight'''
'''
Tests to see whether results are identical for surface-based
searchlight (just one plane; Euclidean distnace) and volume-based
searchlight.
Note that the current value is a float; if it were int, it would
specify the number of voxels in each searchlight'''
radius = 10.
'''Define input filenames'''
epi_fn = os.path.join(pymvpa_dataroot, 'bold.nii.gz')
maskfn = os.path.join(pymvpa_dataroot, 'mask.nii.gz')
'''
Use the EPI datafile to define a surface.
The surface has as many nodes as there are voxels
and is parallel to the volume 'slice'
'''
vg = volgeom.from_any(maskfn, mask_volume=True)
aff = vg.affine
nx, ny, nz = vg.shape[:3]
'''Plane goes in x and y direction, so we take these vectors
from the affine transformation matrix of the volume'''
plane = surf.generate_plane(aff[:3, 3], aff[:3, 0], aff[:3, 1], nx, ny)
'''
Simulate pial and white matter as just above and below
the central plane
'''
normal_vec = aff[:3, 2]
outer = plane + normal_vec
inner = plane + -normal_vec
'''
Combine volume and surface information
'''
vsm = volsurf.VolSurfMaximalMapping(vg, outer, inner)
'''
Run voxel selection with specified radius (in mm), using
Euclidean distance measure
'''
surf_voxsel = surf_voxel_selection.voxel_selection(vsm,
radius,
distance_metric='e')
'''Define the measure'''
# run_slow=True would give an actual cross-validation with meaningful
# accuracies. Because this is a unit-test only the number of voxels
# in each searchlight is tested.
run_slow = False
if run_slow:
meas = CrossValidation(GNB(),
OddEvenPartitioner(),
errorfx=lambda p, t: np.mean(p == t))
postproc = mean_sample
else:
meas = _Voxel_Count_Measure()
postproc = lambda x: x
'''
Surface analysis: define the query engine, cross validation,
and searchlight
'''
surf_qe = SurfaceVerticesQueryEngine(surf_voxsel)
surf_sl = Searchlight(meas, queryengine=surf_qe, postproc=postproc)
'''
new (Sep 2012): also test 'simple' queryengine wrapper function
'''
surf_qe2 = disc_surface_queryengine(radius,
maskfn,
inner,
outer,
plane,
volume_mask=True,
distance_metric='euclidean')
surf_sl2 = Searchlight(meas, queryengine=surf_qe2, postproc=postproc)
'''
Same for the volume analysis
'''
element_sizes = tuple(map(abs, (aff[0, 0], aff[1, 1], aff[2, 2])))
sph = Sphere(radius, element_sizes=element_sizes)
kwa = {'voxel_indices': sph}
vol_qe = IndexQueryEngine(**kwa)
vol_sl = Searchlight(meas, queryengine=vol_qe, postproc=postproc)
'''The following steps are similar to start_easy.py'''
attr = SampleAttributes(
os.path.join(pymvpa_dataroot, 'attributes_literal.txt'))
mask = surf_voxsel.get_mask()
dataset = fmri_dataset(samples=os.path.join(pymvpa_dataroot,
'bold.nii.gz'),
targets=attr.targets,
chunks=attr.chunks,
mask=mask)
if run_slow:
# do chunkswise linear detrending on dataset
poly_detrend(dataset, polyord=1, chunks_attr='chunks')
# zscore dataset relative to baseline ('rest') mean
zscore(dataset,
chunks_attr='chunks',
param_est=('targets', ['rest']))
# select class face and house for this demo analysis
# would work with full datasets (just a little slower)
dataset = dataset[np.array(
[l in ['face', 'house'] for l in dataset.sa.targets],
dtype='bool')]
'''Apply searchlight to datasets'''
surf_dset = surf_sl(dataset)
surf_dset2 = surf_sl2(dataset)
vol_dset = vol_sl(dataset)
surf_data = surf_dset.samples
surf_data2 = surf_dset2.samples
vol_data = vol_dset.samples
assert_array_equal(surf_data, surf_data2)
assert_array_equal(surf_data, vol_data)
clfswh += \
FeatureSelectionClassifier(
linearSVMC.clone(),
SensitivityBasedFeatureSelection(
SMLRWeights(SMLR(lm=0.1, implementation="C"),
postproc=maxofabs_sample()),
RangeElementSelector(mode='select')),
descr="LinSVM on SMLR(lm=0.1) non-0")
_rfeclf = linearSVMC.clone()
clfswh += \
FeatureSelectionClassifier(
_rfeclf,
SplitRFE(
_rfeclf,
OddEvenPartitioner(),
fselector=FractionTailSelector(
0.2, mode='discard', tail='lower')),
descr="LinSVM with nested-CV RFE")
_clfs_splitrfe_svm_anova = \
FeatureSelectionClassifier(
linearSVMC.clone(),
SplitRFE(
linearSVMC.clone(),
OddEvenPartitioner(),
fselector=FractionTailSelector(
0.2, mode='discard', tail='lower'),
fmeasure=OneWayAnova()),
descr="LinSVM with nested-CV Anova RFE")
clfswh += _clfs_splitrfe_svm_anova
def get_dsm_roi_secondorder_xval2(ds,
rois,
zscore_ds=True,
part=OddEvenPartitioner(),
cond_chunk='condition'):
""" Obtain second-order dissimilarities between ROIs. This version
cross-validates at the second level, thus the resulting dsms are
not symmetrical.
Arguments
--------
ds: dataset
rois: dict
each item in the dictionary must be a tuple where the 0th element is
the center of the roi, and the 1st element is a list of ids
zscore_ds: bool
is the dset already zscored?
part: partitioner
cond_chunk: str
across which sample attribute to perform mean group sample
Returns
-------
dataset containing second level dsm
"""
#ds = h5load(fns.betafn(subnr))
#ds = ds[:, mask_]
#ds = ds[ds.sa.condition != 'self']
if zscore_ds:
zscore(ds, chunks_attr='chunks')
# set up oddeven partition
#part = OddEvenPartitioner()
rdms = []
mgs = mean_group_sample([cond_chunk])
dissims_folds = []
for ds_ in part.generate(ds):
ds_1 = ds_[ds_.sa.partitions == 1]
ds_2 = ds_[ds_.sa.partitions == 2]
ds_1 = mgs(ds_1)
ds_2 = mgs(ds_2)
assert (ds_1.samples.shape == ds_2.samples.shape)
# first generate first-order rdms for each fold
names = []
centers = []
dissims_1 = []
dissims_2 = []
for roi, (center, ids) in rois.iteritems():
names.append(roi)
centers.append(center)
sample1_roi = ds_1.samples[:, ids]
sample2_roi = ds_2.samples[:, ids]
dissim1_roi = pdist(sample1_roi, 'correlation')
dissim2_roi = pdist(sample2_roi, 'correlation')
dissims_1.append(dissim1_roi)
dissims_2.append(dissim2_roi)
dss1 = np.array(dissims_1)
dss2 = np.array(dissims_2)
# now compute second-order rdm correlating across folds
dissim_2ndorder = 1. - corrcoefxy(dss1.T, dss2.T)
dissim_2ndorder = dataset_wizard(dissim_2ndorder, targets=names)
dissim_2ndorder.sa['centers'] = centers
# also add fa information about roi
dissim_2ndorder.fa['roi'] = names
dissims_folds.append(dissim_2ndorder)
# average
dissims = dissims_folds[0]
for d in dissims_folds[1:]:
dissims.samples += d.samples
dissims.samples /= len(dissims_folds)
return dissims
def get_dsm_roi_xval1(ds,
rois,
zscore_ds=True,
part=OddEvenPartitioner(),
cond_chunk='condition'):
""" Obtain second-order dissimilarities between ROIs. This version
cross-validates at the first level, thus the resulting dsms are
symmetrical.
Arguments
--------
ds: dataset
rois: dict
each item in the dictionary must be a tuple where the 0th element is
the center of the roi, and the 1st element is a list of ids
zscore_ds: bool
is the dset already zscored?
part: partitioner
cond_chunk: str
across which sample attribute to perform mean group sample
Returns
-------
dataset containing second level dsm
"""
#ds = h5load(fns.betafn(subnr))
#ds = ds[:, mask_]
#ds = ds[ds.sa.condition != 'self']
if zscore_ds:
zscore(ds, chunks_attr='chunks')
# set up oddeven partition
#part = OddEvenPartitioner()
rdms = []
mgs = mean_group_sample([cond_chunk])
dissims_folds = []
for ds_ in part.generate(ds):
ds_1 = ds_[ds_.sa.partitions == 1]
ds_2 = ds_[ds_.sa.partitions == 2]
ds_1 = mgs(ds_1)
ds_2 = mgs(ds_2)
assert (ds_1.samples.shape == ds_2.samples.shape)
# first generate first-order rdms cross-validated across folds
names = []
centers = []
dissims = []
for roi, (center, ids) in rois.iteritems():
names.append(roi)
centers.append(center)
sample1_roi = ds_1.samples[:, ids]
sample2_roi = ds_2.samples[:, ids]
dissim_roi = 1. - corrcoefxy(sample1_roi.T, sample2_roi.T)
nsamples = ds_1.nsamples
assert (dissim_roi.shape == (nsamples, nsamples))
dissims.append(
dissim_roi.flatten()) # now the RDM is not symmetrical anymore
dissims_folds.append(np.array(dissims))
# average across folds
dissims_folds = np.array(dissims_folds).mean(axis=0)
assert (dissims_folds.shape == (len(names), nsamples**2))
# now compute second level (distances)
distance_roi = dist.pdist(dissims_folds, metric='correlation')
dissims_folds = dataset_wizard(dist.squareform(distance_roi),
targets=names)
dissims_folds.fa['roi'] = names
dissims_folds.sa['centers'] = centers
return dissims_folds
def test_rfe(self, clf):
# sensitivity analyser and transfer error quantifier use the SAME clf!
sens_ana = clf.get_sensitivity_analyzer(postproc=maxofabs_sample())
pmeasure = ProxyMeasure(clf,
postproc=BinaryFxNode(mean_mismatch_error,
'targets'))
cvmeasure = CrossValidation(clf,
NFoldPartitioner(),
errorfx=mean_mismatch_error,
postproc=mean_sample())
rfesvm_split = SplitClassifier(clf, OddEvenPartitioner())
# explore few recipes
for rfe, data in [
# because the clf is already trained when computing the sensitivity
# map, prevent retraining for transfer error calculation
# Use absolute of the svm weights as sensitivity
(RFE(sens_ana,
pmeasure,
Splitter('train'),
fselector=FixedNElementTailSelector(1),
train_pmeasure=False), self.get_data()),
# use cross-validation within training to get error for the stopping point
# but use full training data to derive sensitivity
(
RFE(
sens_ana,
cvmeasure,
Repeater(
2
), # give the same full dataset to sens_ana and cvmeasure
fselector=FractionTailSelector(0.70,
mode='select',
tail='upper'),
train_pmeasure=True),
normal_feature_dataset(perlabel=20,
nchunks=5,
nfeatures=200,
nonbogus_features=[0, 1],
snr=1.5)),
# use cross-validation (via SplitClassifier) and get mean
# of normed sensitivities across those splits
(
RFE(
rfesvm_split.get_sensitivity_analyzer(
postproc=ChainMapper([
FxMapper('features', l2_normed),
FxMapper('samples', np.mean),
FxMapper('samples', np.abs)
])),
ConfusionBasedError(rfesvm_split, confusion_state='stats'),
Repeater(
2), # we will use the same full cv-training dataset
fselector=FractionTailSelector(0.50,
mode='select',
tail='upper'),
stopping_criterion=NBackHistoryStopCrit(
BestDetector(), 10),
train_pmeasure=
False, # we just extract it from existing confusion
update_sensitivity=True),
normal_feature_dataset(perlabel=28,
nchunks=7,
nfeatures=200,
nonbogus_features=[0, 1],
snr=1.5))
]:
# prep data
# data = datasets['uni2medium']
data_nfeatures = data.nfeatures
rfe.train(data)
resds = rfe(data)
# fail if orig datasets are changed
self.assertTrue(data.nfeatures == data_nfeatures)
# check that the features set with the least error is selected
if len(rfe.ca.errors):
e = np.array(rfe.ca.errors)
if isinstance(rfe._fselector, FixedNElementTailSelector):
self.assertTrue(resds.nfeatures == data_nfeatures -
e.argmin())
else:
imin = np.argmin(e)
if 'does_feature_selection' in clf.__tags__:
# if clf is smart it might figure it out right away
assert_array_less(imin, len(e))
else:
# in this case we can even check if we had actual
# going down/up trend... although -- why up???
self.assertTrue(1 < imin < len(e) - 1)
else:
self.assertTrue(resds.nfeatures == data_nfeatures)
# silly check if nfeatures is in decreasing order
nfeatures = np.array(rfe.ca.nfeatures).copy()
nfeatures.sort()
self.assertTrue((nfeatures[::-1] == rfe.ca.nfeatures).all())
# check if history has elements for every step
self.assertTrue(
set(rfe.ca.history) == set(range(len(np.array(
rfe.ca.errors)))))
# Last (the largest number) can be present multiple times even
# if we remove 1 feature at a time -- just need to stop well
# in advance when we have more than 1 feature left ;)
self.assertTrue(rfe.ca.nfeatures[-1] == len(
np.where(rfe.ca.history == max(rfe.ca.history))[0]))
def get_dsm_roi_xval1_firstlev(ds,
rois,
zscore_ds=True,
part=OddEvenPartitioner(),
cond_chunk='condition',
fisher=False):
""" Obtain second-order dissimilarities between ROIs. This version
cross-validates at the first level and returns only the first level,
without distances between ROIs
Arguments
--------
ds: dataset
rois: dict
each item in the dictionary must be a tuple where the 0th element is
the center of the roi, and the 1st element is a list of ids
zscore_ds: bool
is the dset already zscored?
part: partitioner
cond_chunk: str
across which sample attribute to perform mean group sample
fisher: bool
whether to fisher-transform the correlations before averaging across folds
Returns
-------
dataset containing first level dsm of shape (nrois, ncond**2)
"""
#ds = h5load(fns.betafn(subnr))
#ds = ds[:, mask_]
#ds = ds[ds.sa.condition != 'self']
# set up oddeven partition
#part = OddEvenPartitioner()
mgs = mean_group_sample([cond_chunk])
dissims_folds = []
folds = 1
for ds_ in part.generate(ds):
print("Running fold {0}".format(folds))
ds_1 = ds_[ds_.sa.partitions == 1]
ds_2 = ds_[ds_.sa.partitions == 2]
ds_1 = mgs(ds_1)
ds_2 = mgs(ds_2)
if ds_1.nsamples >= 4 and zscore_ds:
zscore(ds_1, chunks_attr='chunks')
zscore(ds_2, chunks_attr='chunks')
assert (ds_1.samples.shape == ds_2.samples.shape)
# first generate first-order rdms cross-validated across folds
names = []
centers = []
dissims = []
for roi, (center, ids) in rois.iteritems():
names.append(roi)
centers.append(center)
sample1_roi = ds_1.samples[:, ids]
sample2_roi = ds_2.samples[:, ids]
dissim_roi = corrcoefxy(sample1_roi.T,
sample2_roi.T,
fisher=fisher)
nsamples = ds_1.nsamples
assert (dissim_roi.shape == (nsamples, nsamples))
dissims.append(
dissim_roi.flatten()) # now the RDM is not symmetrical anymore
dissims_folds.append(np.array(dissims))
folds += 1
# average across folds
dissims_folds = np.array(dissims_folds).mean(axis=0)
assert (dissims_folds.shape == (len(names), nsamples**2))
if fisher:
dissims_folds = np.tanh(dissims_folds)
dissims_folds = dataset_wizard(dissims_folds, targets=names)
dissims_folds.sa['centers'] = centers
return dissims_folds
from mvpa2.clfs.svm import LinearCSVMC
from mvpa2.measures.base import CrossValidation
from mvpa2.measures.searchlight import sphere_searchlight
from mvpa2.testing.datasets import datasets
from mvpa2.mappers.fx import mean_sample
"""For the sake of simplicity, let's use a small artificial dataset."""
# Lets just use our tiny 4D dataset from testing battery
dataset = datasets['3dlarge']
"""Now it only takes three lines for a searchlight analysis."""
# setup measure to be computed in each sphere (cross-validated
# generalization error on odd/even splits)
cv = CrossValidation(LinearCSVMC(), OddEvenPartitioner())
# setup searchlight with 2 voxels radius and measure configured above
sl = sphere_searchlight(cv, radius=2, space='myspace',
postproc=mean_sample())
# run searchlight on dataset
sl_map = sl(dataset)
print 'Best performing sphere error:', np.min(sl_map.samples)
"""
If this analysis is done on a fMRI dataset using `NiftiDataset` the resulting
searchlight map (`sl_map`) can be mapped back into the original dataspace
and viewed as a brain overlay. :ref:`Another example <example_searchlight>`
shows a typical application of this algorithm.
def generate_testing_datasets(specs):
# Lets permute upon each invocation of test, so we could possibly
# trigger some funny cases
nonbogus_pool = np.random.permutation([0, 1, 3, 5])
datasets = {}
# use a partitioner to flag odd/even samples as training and test
ttp = OddEvenPartitioner(space='train', count=1)
for kind, spec in specs.iteritems():
# set of univariate datasets
for nlabels in [2, 3, 4]:
basename = 'uni%d%s' % (nlabels, kind)
nonbogus_features = nonbogus_pool[:nlabels]
dataset = normal_feature_dataset(
nlabels=nlabels, nonbogus_features=nonbogus_features, **spec)
# full dataset
datasets[basename] = list(ttp.generate(dataset))[0]
# sample 3D
total = 2 * spec['perlabel']
nchunks = spec['nchunks']
data = np.random.standard_normal((total, 3, 6, 6))
labels = np.concatenate(
(np.repeat(0, spec['perlabel']), np.repeat(1, spec['perlabel'])))
data[:, 1, 0, 0] += 2 * labels # add some signal
chunks = np.asarray(range(nchunks) * (total // nchunks))
mask = np.ones((3, 6, 6), dtype='bool')
mask[0, 0, 0] = 0
mask[1, 3, 2] = 0
ds = Dataset.from_wizard(samples=data,
targets=labels,
chunks=chunks,
mask=mask,
space='myspace')
# and to stress tests on manipulating sa/fa possibly containing
# attributes of dtype object
ds.sa['test_object'] = [['a'], [1, 2]] * (ds.nsamples // 2)
datasets['3d%s' % kind] = ds
# some additional datasets
datasets['dumb2'] = dumb_feature_binary_dataset()
datasets['dumb'] = dumb_feature_dataset()
# dataset with few invariant features
_dsinv = dumb_feature_dataset()
_dsinv.samples = np.hstack((_dsinv.samples, np.zeros(
(_dsinv.nsamples, 1)), np.ones((_dsinv.nsamples, 1))))
datasets['dumbinv'] = _dsinv
# Datasets for regressions testing
datasets['sin_modulated'] = list(
ttp.generate(multiple_chunks(sin_modulated, 4, 30, 1)))[0]
# use the same full for training
datasets['sin_modulated_train'] = datasets['sin_modulated']
datasets['sin_modulated_test'] = sin_modulated(30, 1, flat=True)
# simple signal for linear regressors
datasets['chirp_linear'] = multiple_chunks(chirp_linear, 6, 50, 10, 2, 0.3,
0.1)
datasets['chirp_linear_test'] = chirp_linear(20, 5, 2, 0.4, 0.1)
datasets['wr1996'] = multiple_chunks(wr1996, 4, 50)
datasets['wr1996_test'] = wr1996(50)
datasets['hollow'] = Dataset(HollowSamples((40, 20)),
sa={'targets': np.tile(['one', 'two'], 20)})
return datasets
def test_regressions(self, regr):
"""Simple tests on regressions
"""
if not externals.exists('scipy'):
raise SkipTest
else:
from mvpa2.misc.errorfx import corr_error
ds = datasets['chirp_linear']
# we want numeric labels to maintain the previous behavior, especially
# since we deal with regressions here
ds.sa.targets = AttributeMap().to_numeric(ds.targets)
cve = CrossValidation(regr, NFoldPartitioner(), postproc=mean_sample(),
errorfx=corr_error, enable_ca=['training_stats', 'stats'])
# check the default
#self.assertTrue(cve.transerror.errorfx is corr_error)
corr = np.asscalar(cve(ds).samples)
# Our CorrErrorFx should never return NaN
self.assertTrue(not np.isnan(corr))
self.assertTrue(corr == cve.ca.stats.stats['CCe'])
splitregr = SplitClassifier(
regr, partitioner=OddEvenPartitioner(),
enable_ca=['training_stats', 'stats'])
splitregr.train(ds)
split_corr = splitregr.ca.stats.stats['CCe']
split_corr_tr = splitregr.ca.training_stats.stats['CCe']
for confusion, error in (
(cve.ca.stats, corr),
(splitregr.ca.stats, split_corr),
(splitregr.ca.training_stats, split_corr_tr),
):
#TODO: test confusion statistics
# Part of it for now -- CCe
for conf in confusion.summaries:
stats = conf.stats
if cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(stats['CCe'] < 0.5)
self.assertEqual(stats['CCe'], stats['Summary CCe'])
s0 = confusion.as_string(short=True)
s1 = confusion.as_string(short=False)
for s in [s0, s1]:
self.assertTrue(len(s) > 10,
msg="We should get some string representation "
"of regression summary. Got %s" % s)
if cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(error < 0.2,
msg="Regressions should perform well on a simple "
"dataset. Got correlation error of %s " % error)
# Test access to summary statistics
# YOH: lets start making testing more reliable.
# p-value for such accident to have is verrrry tiny,
# so if regression works -- it better has at least 0.5 ;)
# otherwise fix it! ;)
# YOH: not now -- issues with libsvr in SG and linear kernel
if cfg.getboolean('tests', 'labile', default='yes'):
self.assertTrue(confusion.stats['CCe'] < 0.5)
# just to check if it works fine
split_predictions = splitregr.predict(ds.samples)