[Mne_analysis] Why does MNE resample method does not sample the data point to point?

balandongiv at gmail.com balandongiv at gmail.com
Thu Jul 23 08:28:17 EDT 2020
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While trying with the mne downsampling module, I encountered some behavior
that I am unable to explain myself.

 

My understanding of downsampling is that it is an operation to decrease the
sample rate of x by keeping the first sample and then every nth sample after
the first.

The example provided from the resample method of scipy package clearly
illustrated about this operation as depicted the picture which is accessible
from the link (
<https://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.resample.
html)>
https://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.resample.h
tml) or as extracted below

 

 



 

In an enlarged view, it is evident that the original data points were
resampled point by point.

 

 

However, using the mne example of downsampling which accessible via the link

:  <https://mne.tools/dev/auto_examples/preprocessing/plot_resample.html>
https://mne.tools/dev/auto_examples/preprocessing/plot_resample.html

, I notice that the data points were not resampled point by point as
illustrated visually below

 

 


 



 

 

 

This given that, mne resample is based on the resample method of scipy
package as indicated from mne resample function as shown:

 
<https://github.com/mne-tools/mne-python/blob/607fb4613fb5a80dd225132a4a53fe
43b8fde0fb/mne/filter.py#L1342>
https://github.com/mne-tools/mne-python/blob/607fb4613fb5a80dd225132a4a53fe4
3b8fde0fb/mne/filter.py#L1342

 

 

May I know whether this issue is due to the ringing artifacts or due to
other problems?

 

Also, are there remedies to mitigate this problem.

 

 

Thanks for any insight. Appreciate it

 

 

Cheers

Rodney

 

 

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