[pymvpa] zcore issue/error?

Matthias Ekman Matthias.Ekman at nf.mpg.de
Tue Dec 15 14:42:15 UTC 2009


Hi,

>> I am aware of the fact that it might be not "useful" to calculate
>> chunkwise z-values with only two samples per chunk, but I just wanted to
>> let you know about this issue.
>>     
> yeap ;) thanks!
>
> and I guess everything works fine if dataset.samples.dtype is of some
> float, right?
>   
mh... hate to say so, but adding "dtype=N.float32" doesn't change the 
result. Sorry if I get you wrong here...?

    attr = SampleAttributes(os.path.join(ATTRIBUTES_PATH, ATTRIBUTES_FILE))
    ds = NiftiDataset(samples=os.path.join(BOLD_PATH, BOLD_FILE),
                labels=attr.labels,
                chunks=attr.chunks,
                mask=os.path.join(MASK_PATH, MASK_FILE),
                dtype=N.float32)

Bests,
Matthias

> On Tue, 15 Dec 2009, Matthias Ekman wrote:
>
>   
>> Hi,
>>     
>
>   
>> I am using pymvpa 0.4.3 and getting the following issue/error on both
>> linux and windows machines.
>>     
>
>   
>> In the case of only two samples in a chunk and using zscore with
>> "perchunk=True" the zscoring is not working properly for me. Instead of
>> returning (float) z-values I am getting only integers (either -1 or +1).
>>     
>
>   
>> This behavior occurs with my own data and also with the sample data
>> shipped with PyMVPA. So you might be able to reproduce it.
>>     
>
>   
>> attr = SampleAttributes(os.path.join(pymvpa_dataroot, 'attributes.txt'))
>> dataset = NiftiDataset(samples=os.path.join(pymvpa_dataroot, 'bold.nii.gz'),
>>                        labels=attr.labels,
>>                        chunks=attr.chunks,
>>                        mask=os.path.join(pymvpa_dataroot, 'mask.nii.gz'))
>>     
>
>   
>> zscore(dataset, perchunk=True, targetdtype='float32')
>> dataset.map2Nifti(dataset).save('tmp.nii.gz')
>>     
>
>   
>> Instead of the original attributes.txt-file I used a faked one with only
>> two samples in the first chunk.
>>     
>
>   
>> I am aware of the fact that it might be not "useful" to calculate
>> chunkwise z-values with only two samples per chunk, but I just wanted to
>> let you know about this issue.
>>     
>
>   
>> Best regards,
>> Matthias
>>     
>
>   
>> what the f*ck info:
>>     
>
>   
>> PyMVPA:
>>  Version:       0.4.3
>>  Path:
>> /daten/mekman/3rd/local_pymvpa_installations/043/lib64/python2.5/site-packages/mvpa/__init__.pyc
>>  Version control (GIT):
>>  GIT information could not be obtained due
>> "/daten/mekman/3rd/local_pymvpa_installations/043/lib64/python2.5/site-packages/mvpa/..
>> is not under GIT"
>> SYSTEM:
>>  OS:            posix Linux 2.6.27.7-134.fc10.x86_64 #1 SMP Mon Dec 1
>> 22:21:35 EST 2008
>>  Distribution:  redhat/10/Cambridge
>> EXTERNALS:
>>  Present:       cPickle, ctypes, good scipy.stats.rv_discrete.ppf, gzip,
>> libsvm, libsvm verbosity control, nifti, nifti ge 0.20090205.1, numpy,
>> reportlab, scipy, weave
>>  Absent:        atlas_fsl, atlas_pymvpa, elasticnet, glmnet, good
>> scipy.stats.rdist, griddata, hcluster, lars, lxml, matplotlib, mdp, mdp
>> ge 2.4, openopt, pylab, pylab plottable, pywt, pywt wp reconstruct, pywt
>> wp reconstruct fixed, rpy, running ipython env, sg ge 0.6.4,
>> sg_fixedcachesize, shogun, shogun.lightsvm, shogun.mpd, shogun.svrlight
>>  Versions of critical externals:
>>   ctypes      : 1.0.3
>>   nifti       : 0.20090303.1
>>   numpy       : 1.2.0
>>   scipy       : 0.7.0
>> RUNTIME:
>>  PyMVPA Environment Variables:
>>   PYTHONPATH          :
>> "/daten/mekman/3rd/local_pymvpa_installations/043/lib64/python2.5/site-packages"
>>  PyMVPA Runtime Configuration:
>>   [externals]
>>   have griddata = no
>>   have good scipy.stats.rdist = no
>>   have pylab plottable = no
>>   have pywt wp reconstruct = no
>>   have pywt = no
>>   have lxml = no
>>   have running ipython env = no
>>   have ctypes = yes
>>   have sg_fixedcachesize = no
>>   have elasticnet = no
>>   have shogun.mpd = no
>>   have matplotlib = no
>>   have pywt wp reconstruct fixed = no
>>   have scipy = yes
>>   have reportlab = yes
>>   have openopt = no
>>   have libsvm = yes
>>   have nifti ge 0.20090205.1 = yes
>>   have weave = yes
>>   have atlas_fsl = no
>>   have mdp = no
>>   have hcluster = no
>>   have sg ge 0.6.4 = no
>>   have good scipy.stats.rv_discrete.ppf = yes
>>   have libsvm verbosity control = yes
>>   have mdp ge 2.4 = no
>>   have shogun.svrlight = no
>>   have rpy = no
>>   have shogun = no
>>   have glmnet = no
>>   have lars = no
>>   have atlas_pymvpa = no
>>   have nifti = yes
>>   have cpickle = yes
>>   have numpy = yes
>>   have pylab = no
>>   have shogun.lightsvm = no
>>   have gzip = yes
>>     
>
>   
>>   [general]
>>   verbose = 1
>>  Process Information:
>>   Name: python
>>   State:        R (running)
>>   Tgid: 7499
>>   Pid:  7499
>>   PPid: 6796
>>   TracerPid:    0
>>   Uid:  1515    1515    1515    1515
>>   Gid:  113     113     113     113
>>   FDSize:       256
>>   Groups:       113 6150
>>   VmPeak:         393496 kB
>>   VmSize:         392476 kB
>>   VmLck:               0 kB
>>   VmHWM:           36236 kB
>>   VmRSS:           36200 kB
>>   VmData:          28948 kB
>>   VmStk:             256 kB
>>   VmExe:               4 kB
>>   VmLib:           43336 kB
>>   VmPTE:             724 kB
>>   Threads:      1
>>   SigQ: 1/135168
>>   SigPnd:       0000000000000000
>>   ShdPnd:       0000000000000000
>>   SigBlk:       0000000000000000
>>   SigIgn:       0000000001001000
>>   SigCgt:       0000000180000002
>>   CapInh:       0000000000000000
>>   CapPrm:       0000000000000000
>>   CapEff:       0000000000000000
>>   CapBnd:       ffffffffffffffff
>>   Cpus_allowed: 00000000,0000000f
>>   Cpus_allowed_list:    0-3
>>   Mems_allowed:
>> 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000003
>>   Mems_allowed_list:    0-1
>>   voluntary_ctxt_switches:      2397
>>   nonvoluntary_ctxt_switches:   39
>>     
>
>   
>> _______________________________________________
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>> Pkg-ExpPsy-PyMVPA at lists.alioth.debian.org
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>>     
>
>
>   




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