[pymvpa] hyperalignment inquiry

David Soto d.soto.b at gmail.com
Mon Aug 1 13:30:54 UTC 2016


Hi Swaroop, I have run the analyses using the individual copes that were
co-registered in FSL to the individual T1 (using BBR) and then to MNI2mm
template using a 12 DOF.  The problem persists even after doing
remove_invariant_features().
I get a similar  'Indexerror: index 226822 is out of bounds for axis 1 with
size 198603'

I have uploaded all the datafiles which you can find in the link below,
just in case you could have a look. If you open the zip then you will find
all the relevant files, including the pymvpa script that I use to run the
analyses ('hyperalscript.py'), the individual data within a folder and also
the attributes file and the MNI brain mask
https://drive.google.com/open?id=0B7-qbWx3g9KfUU1jOFVpQ05oRWM

any help would be much appreciated...

thanks!
david

On 29 July 2016 at 18:28, Swaroop Guntupalli <swaroopgj at gmail.com> wrote:

> That is correct. But the searchlight centers across subjects are assumed
> to be aligned.
>
>
> On Fri, Jul 29, 2016 at 8:24 AM, David Soto <d.soto.b at gmail.com> wrote:
>
>> ​Hi, thanks I will try that,  I understand therefore that the number of
>> features per subject need not be equal across subjects for searchlight
>> hyperalignment - but please correct me if am wrong.
>> best
>> david
>>
>> On 29 July 2016 at 16:17, Swaroop Guntupalli <swaroopgj at gmail.com> wrote:
>>
>>> Hi David,
>>>
>>> If you are using searchlight hyperalignment, it is advisable to align
>>> the data across subjects using anatomy first. Simplest would be to be align
>>> them to an MNI template and then run the searchlight hyperalignment.
>>> Our tutorial dataset is affine aligned to MNI template.
>>>
>>> Best,
>>> Swaroop
>>>
>>> On Thu, Jul 28, 2016 at 10:51 AM, David Soto <d.soto.b at gmail.com> wrote:
>>>
>>>> Thanks Swaroop, I managed to get the dataset in the right format as per
>>>> the hyperaligmentsearchlight tutorial
>>>> however when I run the hyperaligment I get the following error (IndexError:
>>>> index 46268 is out of bounds for axis 1 with size 43506, see further
>>>> below)...to recap the dataset is a concatenation of each subject data, each
>>>> in individual native space, so number of features are different across
>>>> subjects...
>>>> The code I use is the same as in the tutorial, namely, any feedback
>>>> would be great, thanks, david
>>>> cv = CrossValidation(clf, NFoldPartitioner(attr='subject'),
>>>>                      errorfx=mean_match_accuracy)
>>>>
>>>> for test_run in range(nruns):
>>>>     ds_train = [sd[sd.sa.chunks != test_run, :] for sd in ds_all]
>>>>     ds_test = [sd[sd.sa.chunks == test_run, :] for sd in ds_all]
>>>>
>>>>     slhyper = SearchlightHyperalignment(radius=3, featsel=0.4,
>>>> sparse_radius=3)
>>>>     slhypmaps = slhyper(ds_train)
>>>>     ds_hyper = [h.forward(sd) for h, sd in zip(slhypmaps, ds_test)]
>>>>
>>>>     ds_hyper = vstack(ds_hyper)
>>>>     zscore(ds_hyper, chunks_attr='subject')
>>>>     res_cv = cv(ds_hyper)
>>>>     bsc_slhyper_results.append(res_cv)
>>>>
>>>> OUTPUT MESSAGE.........
>>>> Performing classification analyses...
>>>>   between-subject (searchlight hyperaligned)...
>>>>
>>>> ------------------------------------------------------------
>>>> ---------------
>>>> IndexError                                Traceback (most recent call
>>>> last)
>>>> <ipython-input-191-85bdb873d4f1> in <module>()
>>>>      24     # Searchlight Hyperalignment returns a list of mappers
>>>> corresponding to
>>>>      25     # subjects in the same order as the list of datasets we
>>>> passed in.
>>>> ---> 26     slhypmaps = slhyper(ds_train)
>>>>      27
>>>>      28     # Applying hyperalignment parameters is similar to applying
>>>> any mapper in
>>>>
>>>> /usr/local/lib/python2.7/site-packages/mvpa2/algorithms/searchlight_hyperalignment.pyc
>>>> in __call__(self, datasets)
>>>>     626             node_blocks = np.array_split(roi_ids,
>>>> params.nblocks)
>>>>     627             p_results = [self._proc_block(block, datasets,
>>>> hmeasure, queryengines)
>>>> --> 628                          for block in node_blocks]
>>>>     629         results_ds = self.__handle_all_results(p_results)
>>>>     630         # Dummy iterator for, you know, iteration
>>>>
>>>> /usr/local/lib/python2.7/site-packages/mvpa2/algorithms/searchlight_hyperalignment.pyc
>>>> in _proc_block(self, block, datasets, featselhyper, queryengines, seed,
>>>> iblock)
>>>>     387                 continue
>>>>     388             # selecting neighborhood for all subject for
>>>> hyperalignment
>>>> --> 389             ds_temp = [sd[:, ids] for sd, ids in zip(datasets,
>>>> roi_feature_ids_all)]
>>>>     390             if self.force_roi_seed:
>>>>     391                 roi_seed = np.array(roi_feature_ids_all[self.params.ref_ds])
>>>> == node_id
>>>>
>>>> /usr/local/lib/python2.7/site-packages/mvpa2/datasets/base.pyc in
>>>> __getitem__(self, args)
>>>>     139
>>>>     140         # let the base do the work
>>>> --> 141         ds = super(Dataset, self).__getitem__(args)
>>>>     142
>>>>     143         # and adjusting the mapper (if any)
>>>>
>>>> /usr/local/lib/python2.7/site-packages/mvpa2/base/dataset.pyc in
>>>> __getitem__(self, args)
>>>>     445         if isinstance(self.samples, np.ndarray):
>>>>     446             if np.any([isinstance(a, slice) for a in args]):
>>>> --> 447                 samples = self.samples[args[0], args[1]]
>>>>     448             else:
>>>>     449                 # works even with bool masks (although without
>>>>
>>>> IndexError: index 46268 is out of bounds for axis 1 with size 43506
>>>>
>>>> On 28 July 2016 at 00:25, Swaroop Guntupalli <swaroopgj at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi David,
>>>>>
>>>>> If you have limited data, you can use a part of it (however you split
>>>>> the data for training and testing)
>>>>> to train hyperalignment, and also use the same part to train the
>>>>> classifier and then apply hyperalignment and test classifier on the
>>>>> left-out part. Yes, you can artificially create 2 chunks (or more if you
>>>>> prefer).
>>>>>
>>>>>
>>>>> On Wed, Jul 27, 2016 at 3:17 PM, David Soto <d.soto.b at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> sounds great thanks, a further thing is that I have seen that in
>>>>>> order to preclude  circularity issues, hyperalinment is implemented on a
>>>>>> subset of training chunks and then the transformation is applied to the
>>>>>> full datasets prior to classification analyses.  Given that I have no
>>>>>> proper chunks/runs here, but only 56 betas across trials, would it be okay
>>>>>> to train hyperaligment just on half of the 56 betas, eg artificially split
>>>>>> the data set in 2 chunks  each containing 14 betas of class A and 14 of
>>>>>> class B? Or would it be just OK to train hyperaligment on the 56 betas in
>>>>>> the first instance?
>>>>>> thanks!
>>>>>> david
>>>>>>
>>>>>> On 28 July 2016 at 00:00, Swaroop Guntupalli <swaroopgj at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> The hyperalignment example on PyMVPA uses one beta map for each
>>>>>>> category per run.
>>>>>>>
>>>>>>> On Wed, Jul 27, 2016 at 2:57 PM, Swaroop Guntupalli <
>>>>>>> swaroopgj at gmail.com> wrote:
>>>>>>>
>>>>>>>> Hi David,
>>>>>>>>
>>>>>>>> Beta maps should work fine for hyperalignment. The more maps (or
>>>>>>>> TRs) there are, better the estimate.
>>>>>>>> We used within-subject hyperalignment in Haxby et al. 2011, which
>>>>>>>> uses maps from 6 categories (we used 3 successive betas per condition I
>>>>>>>> think).
>>>>>>>>
>>>>>>>> vstack() merges multiple datasets into a single dataset, and if
>>>>>>>> there is any voxel count (nfeatures) mismatch across subjects, it won't
>>>>>>>> work (as evidenced by the error).
>>>>>>>> Hyperalignment takes in a list of datasets, one per each subject.
>>>>>>>> So, you can make that a list as
>>>>>>>> ds_all =[ds1, ds2, ...., ds16]
>>>>>>>> and use for Hyperalignment()
>>>>>>>>
>>>>>>>> Best,
>>>>>>>> Swaroop
>>>>>>>>
>>>>>>>>
>>>>>>>> On Wed, Jul 27, 2016 at 2:28 PM, David Soto <d.soto.b at gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> hi,
>>>>>>>>>
>>>>>>>>> in my experiment I have 28 betas in condition A and 28 parameter
>>>>>>>>> estimate images and 28  in condition B for each subject (N=16 in total).
>>>>>>>>>
>>>>>>>>> i have performed across-subjects SVM-based searchlight
>>>>>>>>> classification using MNI-registered individual beta images and I would like
>>>>>>>>> to repeat and confirm my results using searchlight based on hyperaligned
>>>>>>>>> data.
>>>>>>>>>
>>>>>>>>> i am not aware of any paper using hyperaligment on  beta images
>>>>>>>>> but I think this should be possible, any advise please would be nice
>>>>>>>>>
>>>>>>>>> i've created individual datasets concatenating the 28 betas in
>>>>>>>>> condition A and the 28 in condition (in the actual experiment condition A
>>>>>>>>> and B can appear randomly on each trial). I have 16 nifti datasets, one per
>>>>>>>>> subject, with each in individual native anatomical space. In trying to get
>>>>>>>>> a dataset in the same format as in the hyperlignment tutorial I use
>>>>>>>>> fmri_dataset on each individual wholebrain 48 betas  and then try to merged
>>>>>>>>> then all i.e. ds_merged = vstack((d1, d2, d3, d4, d5, d6, d7, d8,
>>>>>>>>> d9, d10, d11, d12, d13, d14, d15,d16)) but this gives the following error
>>>>>>>>> pasted at the end,
>>>>>>>>> which I think it is becos the number of voxels is different across
>>>>>>>>> subjects. This is one issue.
>>>>>>>>>
>>>>>>>>> Another is that the function vstack does appear to produce the
>>>>>>>>> list of individual datasets that is in the hyperligment tutorial dataset,
>>>>>>>>> but a list of individual betas, I would be grateful to receive some tips.
>>>>>>>>>
>>>>>>>>> thanks!
>>>>>>>>> david
>>>>>>>>> ------------------------------------------------------------
>>>>>>>>> ---------------
>>>>>>>>> ValueError                                Traceback (most recent
>>>>>>>>> call last)
>>>>>>>>> <ipython-input-64-2fef46542bfc> in <module>()
>>>>>>>>>      19 h5save('/home/dsoto/dsoto/fmri/wmlearning/h5.hdf5',
>>>>>>>>> [d1,d2])
>>>>>>>>>      20 #ds_merged = vstack((d1, d2, d3, d4, d5, d6, d7,d8,d9,
>>>>>>>>> d10, d11, d12, d13, d14, d15, d16))
>>>>>>>>> ---> 21 ds_merged = vstack((d1, d2))
>>>>>>>>>
>>>>>>>>> /usr/local/lib/python2.7/site-packages/mvpa2/base/dataset.pyc in
>>>>>>>>> vstack(datasets, a)
>>>>>>>>>     687                              "datasets have varying
>>>>>>>>> attributes.")
>>>>>>>>>     688     # will puke if not equal number of features
>>>>>>>>> --> 689     stacked_samp = np.concatenate([ds.samples for ds in
>>>>>>>>> datasets], axis=0)
>>>>>>>>>     690
>>>>>>>>>     691     stacked_sa = {}
>>>>>>>>>
>>>>>>>>> ValueError: all the input array dimensions except for the
>>>>>>>>> concatenation axis must match exactly
>>>>>>>>>
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>>>>>>>>
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