[Mne_analysis] How to filter harmonics?

[Eric Larson]

raw.filter() operates inplace (and doesn't return anything, which is why
you get None as a result), so your raw object is now filtered.

You can use raw_2 = raw.copy(), raw_2.filter(...) if you don't want to
modify your original raw instance.

Eric


On Wed, Mar 23, 2016 at 1:31 PM, Megan Schendel <mschendel at mrn.org> wrote:

> Hi all,
>      I've also been trying to figure out filtering, and getting a bit
> stuck on what to do with the result of such.  If I follow along above and
> then do something like:
>
> filtered_data = raw.notch_filter(freqs=harmonics[:-1]+noise_freq//2,
> notch_widths=noise_freq - 2*width)
>
> I can't treat the result like a raw RawFIF, and if I ask python
>
> type(filtered_data)
> NoneType
>
> So how does one use (say, plot) such a result?
>
> Thanks!
> Megan
>
>
>
>
> MEG Technician
> The Mind Research Network
> 1101 Yale Blvd. NE
> Albuquerque, New Mexico 87106
> 505-272-3304
>
>
> On Wed, Mar 23, 2016 at 10:10 AM, JR KING <jeanremi.king at gmail.com> wrote:
>
>> Thanks!
>>
>> For the record I did:
>>
>> noise_freq = 60.  # US line noise
>> width = 2. # notch widh in Hz
>>
>> # harmonics until nquist
>> n_harm = raw.info['sfreq'] // (2. * noise_freq) + 1
>>
>> # band pass first to last harmonics
>> harmonics = noise_freq * np.arange(1, n_harm)
>> raw.filter(noise_freq - width, harmonics[-1] + width)
>>
>> # band stop filter in between harmonics (it's not really a notch, since
>> the freq width is very large)
>> raw.notch_filter(freqs=harmonics[:-1]+noise_freq//2,
>> notch_widths=noise_freq - 2*width)
>>
>> JR
>>
>> On 23 March 2016 at 10:13, dgw <dgwakeman at gmail.com> wrote:
>>
>>> Hi JR,
>>>
>>> what about:
>>> bandpass: 55: 245, plus notch filters for the other gaps
>>>
>>> d
>>>
>>> On Wed, Mar 23, 2016 at 10:11 AM, JR KING <jeanremi.king at gmail.com>
>>> wrote:
>>> > Hi all,
>>> >
>>> > Is there a way in MNE to do the opposite of notch-filtering so as to
>>> filter
>>> > out everything but the line noise and its harmonics?
>>> >
>>> > I'm typically trying to filter the signals so as to only keep the 60,
>>> 120,
>>> > 180, 240 Hz frequency bands.
>>> >
>>> > Thanks!
>>> >
>>> > JR
>>> >
>>> >
>>> >
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