Ejemplo n.º 1
0
 def testOLSdegenerate(self):
     X = W((40,10))
     X[:,0] = X[:,1] + X[:,2]
     Y = W((40,))
     model = OLSModel(design=X)
     results = model.fit(Y)
     self.assertEquals(results.df_resid, 31)
Ejemplo n.º 2
0
def test_altprotocol():
    block, bT, bF = protocol(descriptions['block'], 'block', *delay.spectral)
    event, eT, eF = protocol(descriptions['event'], 'event', *delay.spectral)

    blocka, baT, baF = altprotocol(altdescr['block'], 'block', *delay.spectral)
    eventa, eaT, eaF = altprotocol(altdescr['event'], 'event', *delay.spectral)

    for c in bT.keys():
        baf = baT[c]
        if not isinstance(baf, formula.Formula):
            baf = formula.Formula([baf])

        bf = bT[c]
        if not isinstance(bf, formula.Formula):
            bf = formula.Formula([bf])

	X = baf.design(t, return_float=True)
	Y = bf.design(t, return_float=True)
	if X.ndim == 1:
            X.shape = (X.shape[0], 1)
	m = OLSModel(X)
	r = m.fit(Y)
	remaining = (r.resid**2).sum() / (Y**2).sum()
	yield assert_almost_equal, remaining, 0

    for c in bF.keys():
        baf = baF[c]
        if not isinstance(baf, formula.Formula):
            baf = formula.Formula([baf])

        bf = bF[c]
        if not isinstance(bf, formula.Formula):
            bf = formula.Formula([bf])

	X = baf.design(t, return_float=True)
	Y = bf.design(t, return_float=True)
	if X.ndim == 1:
            X.shape = (X.shape[0], 1)
	m = OLSModel(X)
	r = m.fit(Y)
	remaining = (r.resid**2).sum() / (Y**2).sum()
	yield assert_almost_equal, remaining, 0
Ejemplo n.º 3
0
def test_scipy_stats():
    # Using scipy.stats.models

    X, cons = twoway.design(D, contrasts=contrasts)
    Y = D['Days']
    m = OLSModel(X)
    f = m.fit(Y)

    F_m = {}
    df_m = {}
    p_m = {}

    for n, c in cons.items():
        r = f.Fcontrast(c)
        F_m[n] = r.F
        df_m[n] = r.df_num
        p_m[n] = scipy.stats.f.sf(F_m[n], df_m[n], r.df_den)
        assert_almost_equal(F[n], F_m[n])
        assert_almost_equal(df[n], df_m[n])
        assert_almost_equal(p[n], p_m[n])
Ejemplo n.º 4
0
        tempdict[v] = np.zeros(mask_array.sum())
    output[contrast_id] = tempdict


########################################
# Perform a GLM analysis
########################################

print 'Fitting a GLM (this takes time)...'
fmri_image = load(data_path)
Y = fmri_image.get_data()[mask_array]
X = design_matrix.matrix

m = OLSModel(X)
# Fit the model, storing an estimate of an AR(1) parameter at each voxel
result = m.fit(Y.T)
ar1 = ((result.resid[1:] * result.resid[:-1]).sum(0) /
          (result.resid ** 2).sum(0))
ar1 *= 100
ar1 = ar1.astype(np.int) / 100.


for val in np.unique(ar1):
    armask = np.equal(ar1, val)
    m = ARModel(X, val)
    d = Y[armask]
    results = m.fit(d.T)
    
    # Output the results for each contrast
    for (contrast_id, contrast_val) in contrasts.items():
        resT = results.Tcontrast(contrast_val)
Ejemplo n.º 5
0
 def testOLS(self):
     X = W((40,10))
     Y = W((40,))
     model = OLSModel(design=X)
     results = model.fit(Y)
     self.assertEquals(results.df_resid, 30)
Ejemplo n.º 6
0
def run_model(subj, run):
    """
    Single subject fitting of FIAC model
    """
    #----------------------------------------------------------------------
    # Set initial parameters of the FIAC dataset
    #----------------------------------------------------------------------
    # Number of volumes in the fMRI data
    nvol = 191
    # The TR of the experiment
    TR = 2.5 
    # The time of the first volume
    Tstart = 0.0
    # The array of times corresponding to each 
    # volume in the fMRI data
    volume_times = np.arange(nvol)*TR + Tstart
    # This recarray of times has one column named 't'
    # It is used in the function design.event_design
    # to create the design matrices.
    volume_times_rec = formula.make_recarray(volume_times, 't')
    # Get a path description dictionary that contains all the path data
    # relevant to this subject/run
    path_info = futil.path_info(subj,run)

    #----------------------------------------------------------------------
    # Experimental design
    #----------------------------------------------------------------------

    # Load the experimental description from disk.  We have utilities in futil
    # that reformat the original FIAC-supplied format into something where the
    # factorial structure of the design is more explicit.  This has already
    # been run once, and get_experiment_initial() will simply load the
    # newly-formatted design description files (.csv) into record arrays.
    experiment, initial = futil.get_experiment_initial(path_info)
    
    # Create design matrices for the "initial" and "experiment" factors,
    # saving the default contrasts. 

    # The function event_design will create
    # design matrices, which in the case of "experiment"
    # will have num_columns =
    # (# levels of speaker) * (# levels of sentence) * len(delay.spectral) =
    #      2 * 2 * 2 = 8
    # For "initial", there will be
    # (# levels of initial) * len([hrf.glover]) = 1 * 1 = 1

    # Here, delay.spectral is a sequence of 2 symbolic HRFs that 
    # are described in 
    # 
    # Liao, C.H., Worsley, K.J., Poline, J-B., Aston, J.A.D., Duncan, G.H.,
    #    Evans, A.C. (2002). \'Estimating the delay of the response in fMRI
    #    data.\' NeuroImage, 16:593-606.

    # The contrasts, cons_exper,
    # is a dictionary with keys: ['constant_0', 'constant_1', 'speaker_0', 
    # 'speaker_1',
    # 'sentence_0', 'sentence_1', 'sentence:speaker_0', 'sentence:speaker_1']
    # representing the four default contrasts: constant, main effects + 
    # interactions,
    # each convolved with 2 HRFs in delay.spectral. Its values
    # are matrices with 8 columns.

    # XXX use the hrf __repr__ for naming contrasts

    X_exper, cons_exper = design.event_design(experiment, volume_times_rec,
                                              hrfs=delay.spectral)

    # The contrasts for 'initial' are ignored 
    # as they are "uninteresting" and are included
    # in the model as confounds.

    X_initial, _ = design.event_design(initial, volume_times_rec,
                                       hrfs=[hrf.glover]) 

    # In addition to factors, there is typically a "drift" term
    # In this case, the drift is a natural cubic spline with
    # a not at the midpoint (volume_times.mean())

    vt = volume_times # shorthand
    drift = np.array( [vt**i for i in range(4)] +
                      [(vt-vt.mean())**3 * (np.greater(vt, vt.mean()))] )
    for i in range(drift.shape[0]):
        drift[i] /= drift[i].max()

    # We transpose the drift so that its shape is (nvol,5) so that it will have
    # the same number of rows as X_initial and X_exper.
    drift = drift.T

    # There are helper functions to create these drifts: design.fourier_basis,
    # design.natural_spline.  Therefore, the above is equivalent (except for
    # the normalization by max for numerical stability) to
    #
    # >>> drift = design.natural_spline(t, [volume_times.mean()])

    # Stack all the designs, keeping the new contrasts which has the same keys
    # as cons_exper, but its values are arrays with 15 columns, with the
    # non-zero entries matching the columns of X corresponding to X_exper
    X, cons = design.stack_designs((X_exper, cons_exper),
                                   (X_initial, {}),
                                   (drift, {}))

    # Sanity check: delete any non-estimable contrasts
    # XXX - this seems to be broken right now, it's producing bogus warnings.
    ## for k in cons.keys():
    ##     if not isestimable(X, cons[k]):
    ##         del(cons[k])
    ##         warnings.warn("contrast %s not estimable for this run" % k)

    # The default contrasts are all t-statistics.  We may want to output
    # F-statistics for 'speaker', 'sentence', 'speaker:sentence' based on the
    # two coefficients, one for each HRF in delay.spectral

    cons['speaker'] = np.vstack([cons['speaker_0'], cons['speaker_1']])
    cons['sentence'] = np.vstack([cons['sentence_0'], cons['sentence_1']])
    cons['sentence:speaker'] = np.vstack([cons['sentence:speaker_0'], 
                                          cons['sentence:speaker_1']])

    #----------------------------------------------------------------------
    # Data loading
    #----------------------------------------------------------------------
    
    # Load in the fMRI data, saving it as an array
    # It is transposed to have time as the first dimension,
    # i.e. fmri[t] gives the t-th volume.

    fmri, anat = futil.get_fmri_anat(path_info)
    fmri = np.transpose(fmri, [3,0,1,2])

    nvol, volshape = fmri.shape[0], fmri.shape[1:] 
    nslice, sliceshape = volshape[0], volshape[1:]

    #----------------------------------------------------------------------
    # Model fit
    #----------------------------------------------------------------------

    # The model is a two-stage model, the first stage being an OLS (ordinary
    # least squares) fit, whose residuals are used to estimate an AR(1)
    # parameter for each voxel.

    m = OLSModel(X)
    ar1 = np.zeros(volshape)

    # Fit the model, storing an estimate of an AR(1) parameter at each voxel
    for s in range(nslice):
        d = np.array(fmri[:,s])
        flatd = d.reshape((d.shape[0], -1))
        result = m.fit(flatd)
        ar1[s] = ((result.resid[1:] * result.resid[:-1]).sum(0) /
                  (result.resid**2).sum(0)).reshape(sliceshape)

    # We round ar1 to nearest one-hundredth
    # and group voxels by their rounded ar1 value,
    # fitting an AR(1) model to each batch of voxels.

    # XXX smooth here?
    # ar1 = smooth(ar1, 8.0)

    ar1 *= 100
    ar1 = ar1.astype(np.int) / 100.

    # We split the contrasts into F-tests and t-tests.
    # XXX helper function should do this
    
    fcons = {}; tcons = {}
    for n, v in cons.items():
        v = np.squeeze(v)
        if v.ndim == 1:
            tcons[n] = v
        else:
            fcons[n] = v

    # Setup a dictionary to hold all the output
    # XXX ideally these would be memmap'ed Image instances

    output = {}
    for n in tcons:
        tempdict = {}
        for v in ['sd', 't', 'effect']:
            tempdict[v] = np.memmap(NamedTemporaryFile(prefix='%s%s.nii' \
                                    % (n,v)), dtype=np.float, 
                                    shape=volshape, mode='w+')
        output[n] = tempdict
    
    for n in fcons:
        output[n] = np.memmap(NamedTemporaryFile(prefix='%s%s.nii' \
                                    % (n,v)), dtype=np.float, 
                                    shape=volshape, mode='w+')

    # Loop over the unique values of ar1

    for val in np.unique(ar1):
        armask = np.equal(ar1, val)
        m = ARModel(X, val)
        d = fmri[:,armask]
        results = m.fit(d)

        # Output the results for each contrast

        for n in tcons:
            resT = results.Tcontrast(tcons[n])
            output[n]['sd'][armask] = resT.sd
            output[n]['t'][armask] = resT.t
            output[n]['effect'][armask] = resT.effect

        for n in fcons:
            output[n][armask] = results.Fcontrast(fcons[n]).F

    # Dump output to disk
    odir = futil.output_dir(path_info,tcons,fcons)

    for n in tcons:
        for v in ['t', 'sd', 'effect']:
            im = api.Image(output[n][v], anat.coordmap.copy())
            save_image(im, pjoin(odir, n, '%s.nii' % v))

    for n in fcons:
        im = api.Image(output[n], anat.coordmap.copy())
        save_image(im, pjoin(odir, n, "F.nii"))