Re: [Discuss-gnuradio] Trouble decimating after averaging 4 vectors? Help?

[Jeff Long]

You are already telling GR that you are decimating (nave in decim_block 
init). BTW, you are setting self.nave to 0 in init, instead of using the 
value passed in.

GR should always give you a multiple of 4 vectors (I think) since you've 
specified a decim of 4.

On 03/11/2018 04:03 PM, Glen I Langston wrote:
> Thanks Jeff,
>
> I’ll give that a try.
>
> I think I’m also missing something that tells gnu radio what the expected 
> decimation is (?),
> beyond the decimate = 4 parameter(?).
>
> Also concerning your point, then if I have a non-multiple of 4 vectors I guess 
> I need
> to keep the sum and count, but I guess that is already a part of the code.
>
> Best regards
>
> Glen
>
>
>
>
> > On Mar 11, 2018, at 3:54 PM, Jeff Long <address@hidden> wrote:
> >
> > in[0] is not the first vector, it is all of the available input for port 0. So, 
> > you feed in 4 vectors in your test program, and the shape of in[0] is (4,1024). 
> > You're missing a loop that iterates over the input vectors.
> >
> > On 03/11/2018 02:06 PM, Glen I Langston wrote:
> > > Hello Gnuradio experts,
> > > I'm following the gnuradio tutorial for creating an out of tree python block.
> > > My intention is fairly simple.  To have a input stream of 4 vectors
> > > and average these 4 vectors, outputting a single average vector
> > > after the 4th vector arrives.  Right now my vectors are 1024 channel
> > > total power spectra.
> > > My code is attached, along with the quality control code.
> > > I've been at this for a while, but I must have the wrong model
> > > in my head on how gnuradio holds these samples.
> > > I'm not getting the proper size matches.   I can not find any
> > > decimation help, despite hours of googling...
> > > Suggestions?
> > > THanks
> > > Glen
> > > My intention is to make this 4 vector average with decimate a
> > > part of the .grc environment, but the problems are easier to diagnose,
> > > as the QA code is stands alone.   Here are the messages I’m getting:
> > > ESMU:vdecimate glangsto$ python qa_vdecimate.py
> > > handler caught exception: could not broadcast input array from shape (4,1024) 
> > > into shape (1,1024)
> > > Traceback (most recent call last):
> > >    File 
> > > "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/gnuradio/gr/gateway.py",
> > >  line 55, in eval
> > >      try: self._callback()
> > >    File 
> > > "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/gnuradio/gr/gateway.py",
> > >  line 160, in __gr_block_handle
> > >      ) for i in self.__out_indexes],
> > >    File "/Users/glangsto/Desktop/Research/vdecimate/vdecimate.py", line 58, in 
> > > work
> > >      out[:] = self.sum/float(self.count)
> > > ValueError: could not broadcast input array from shape (4,1024) into shape 
> > > (1,1024)
> > > thread[thread-per-block[1]: <block vdecimate (2)>]: SWIG director method error. 
> > > Error detected when calling 'feval_ll.eval'
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