Re: Problem with the OOT forecast() method in Python

[Johannes Demel]

Hi George,

first a few words of caution. Python blocks are intended for quick tests 
and incur a serious performance penalty. Thus, they are actually not 
that well documented in terms of more advanced functionality. Given that 
`forecast` is generally more of a performance optimization function, 
this is not surprising.
It might be interesting to describe your issue in more detail. What are 
you actually trying to do? Maybe the `forecast` method is not the thing 
you actually need to implement.


Please refer to a default implementation for the Python `forecast` method:
https://github.com/gnuradio/gnuradio/blob/09930fdcc5c892eaff5754f6ef0203146bc1cca7/gnuradio-runtime/python/gnuradio/gr/gateway.py#L153

Also:
https://github.com/gnuradio/gnuradio/blob/09930fdcc5c892eaff5754f6ef0203146bc1cca7/gnuradio-runtime/python/gnuradio/gr/gateway.py#L336
This is another example how to implement the forecast method.

The implementations for sync, decimation, and interpolation blocks are 
available and do not need to be implemented separately. This would only 
be necessary for general blocks.


Cheers
Johannes

On 13.10.22 01:00, George Edwards wrote:

Hi Jeff, thanks for bearing with me.

When I retested the last approach just now upon receiving your email it 
works. Earlier, l forgot to take out some extraneous stuff in my code, 
which broke it. The code snippet I sent implies a one to one 
relationship between input and output. The forecaster does its job to 
ensure the number of input samples is at least the same size as the 
output, but in many instances the input is larger. This, however, will 
present a problem to the signal processing algorithm I have in mind 
which requires the post-pending samples (the size of my filter) to the 
end to the incoming data before upsampling. It seems the forecaster may 
be too loose in its input/output sample relationship and will mess up my 
algorithm.


Anyway, if you have any thought on this and do not mind sharing I would 
appreciate it.


Thank again for your assistance.

George

On Wed, Oct 12, 2022, 2:58 PM Jeff Long > wrote:


The last one looks correct, and would not have given the error you
mention above. What happened?

On Wed, Oct 12, 2022 at 4:49 PM George Edwards
mailto:gedwards@gmail.com>> wrote:

Hi Jeff, thank you very much for the response.
I tries:
ninput_items_required[0]=[noutput_items]
ninput_items_required=[noutput_items]
and
return [noutput_items]
None of these worked for me.

Regards
George

On Wed, Oct 12, 2022, 8:07 AM Jeff Long mailto:willco...@gmail.com>> wrote:

For Python, the forecast() function should return a list,
containing the number of items required for each input.

On Wed, Oct 12, 2022 at 8:08 AM George Edwards
mailto:gedwards@gmail.com>> wrote:

Hello GNURadio Community,

I am getting a TypeError when I fill in the code in the
forecast() method in my Gnuradio OOT block design. I
know, if I want to interpolate or decimate, I can simply
pick the block type in the gr_modtool design menu,
however, I would like to develop the capability to
design my own. Here is how I fill in the forecast()
method in Python to do either decimation or interpolation:

ninput_items_required[0] = noutput_items*self.sps  # for
decimation
OR
ninput_items_required[0] = noutput_items/self.sps  # for
interpolation

On running the flowgraph in GRC Console I see TypeError:
'int' object does not support item assignment.

Will appreciate any suggestion to fix this problem.

George



smime.p7s
Description: S/MIME Cryptographic Signature

Re: Problem with the OOT forecast() method in Python

[George Edwards]

Hi Jeff, thanks for bearing with me.

When I retested the last approach just now upon receiving your email it
works. Earlier, l forgot to take out some extraneous stuff in my code,
which broke it. The code snippet I sent implies a one to one relationship
between input and output. The forecaster does its job to ensure the number
of input samples is at least the same size as the output, but in many
instances the input is larger. This, however, will present a problem to the
signal processing algorithm I have in mind which requires the post-pending
samples (the size of my filter) to the end to the incoming data before
upsampling. It seems the forecaster may be too loose in its input/output
sample relationship and will mess up my algorithm.

Anyway, if you have any thought on this and do not mind sharing I would
appreciate it.

Thank again for your assistance.

George

On Wed, Oct 12, 2022, 2:58 PM Jeff Long  wrote:

> The last one looks correct, and would not have given the error you mention
> above. What happened?
>
> On Wed, Oct 12, 2022 at 4:49 PM George Edwards 
> wrote:
>
>> Hi Jeff, thank you very much for the response.
>> I tries:
>> ninput_items_required[0]=[noutput_items]
>> ninput_items_required=[noutput_items]
>> and
>> return [noutput_items]
>> None of these worked for me.
>>
>> Regards
>> George
>>
>> On Wed, Oct 12, 2022, 8:07 AM Jeff Long  wrote:
>>
>>> For Python, the forecast() function should return a list, containing the
>>> number of items required for each input.
>>>
>>> On Wed, Oct 12, 2022 at 8:08 AM George Edwards 
>>> wrote:
>>>
 Hello GNURadio Community,

 I am getting a TypeError when I fill in the code in the forecast()
 method in my Gnuradio OOT block design. I know, if I want to interpolate or
 decimate, I can simply pick the block type in the gr_modtool design menu,
 however, I would like to develop the capability to design my own. Here is
 how I fill in the forecast() method in Python to do either decimation or
 interpolation:

 ninput_items_required[0] = noutput_items*self.sps  # for decimation
 OR
 ninput_items_required[0] = noutput_items/self.sps  # for interpolation

 On running the flowgraph in GRC Console I see TypeError: 'int' object
 does not support item assignment.

 Will appreciate any suggestion to fix this problem.

 George

Re: Problem with the OOT forecast() method in Python

[Jeff Long]

The last one looks correct, and would not have given the error you mention
above. What happened?

On Wed, Oct 12, 2022 at 4:49 PM George Edwards 
wrote:

> Hi Jeff, thank you very much for the response.
> I tries:
> ninput_items_required[0]=[noutput_items]
> ninput_items_required=[noutput_items]
> and
> return [noutput_items]
> None of these worked for me.
>
> Regards
> George
>
> On Wed, Oct 12, 2022, 8:07 AM Jeff Long  wrote:
>
>> For Python, the forecast() function should return a list, containing the
>> number of items required for each input.
>>
>> On Wed, Oct 12, 2022 at 8:08 AM George Edwards 
>> wrote:
>>
>>> Hello GNURadio Community,
>>>
>>> I am getting a TypeError when I fill in the code in the forecast()
>>> method in my Gnuradio OOT block design. I know, if I want to interpolate or
>>> decimate, I can simply pick the block type in the gr_modtool design menu,
>>> however, I would like to develop the capability to design my own. Here is
>>> how I fill in the forecast() method in Python to do either decimation or
>>> interpolation:
>>>
>>> ninput_items_required[0] = noutput_items*self.sps  # for decimation
>>> OR
>>> ninput_items_required[0] = noutput_items/self.sps  # for interpolation
>>>
>>> On running the flowgraph in GRC Console I see TypeError: 'int' object
>>> does not support item assignment.
>>>
>>> Will appreciate any suggestion to fix this problem.
>>>
>>> George
>>>
>>>

Re: Problem with the OOT forecast() method in Python

[George Edwards]

Hi Jeff, thank you very much for the response.
I tries:
ninput_items_required[0]=[noutput_items]
ninput_items_required=[noutput_items]
and
return [noutput_items]
None of these worked for me.

Regards
George

On Wed, Oct 12, 2022, 8:07 AM Jeff Long  wrote:

> For Python, the forecast() function should return a list, containing the
> number of items required for each input.
>
> On Wed, Oct 12, 2022 at 8:08 AM George Edwards 
> wrote:
>
>> Hello GNURadio Community,
>>
>> I am getting a TypeError when I fill in the code in the forecast() method
>> in my Gnuradio OOT block design. I know, if I want to interpolate or
>> decimate, I can simply pick the block type in the gr_modtool design menu,
>> however, I would like to develop the capability to design my own. Here is
>> how I fill in the forecast() method in Python to do either decimation or
>> interpolation:
>>
>> ninput_items_required[0] = noutput_items*self.sps  # for decimation
>> OR
>> ninput_items_required[0] = noutput_items/self.sps  # for interpolation
>>
>> On running the flowgraph in GRC Console I see TypeError: 'int' object
>> does not support item assignment.
>>
>> Will appreciate any suggestion to fix this problem.
>>
>> George
>>
>>

Re: Problem with the OOT forecast() method in Python

[Jeff Long]

For Python, the forecast() function should return a list, containing the
number of items required for each input.

On Wed, Oct 12, 2022 at 8:08 AM George Edwards 
wrote:

> Hello GNURadio Community,
>
> I am getting a TypeError when I fill in the code in the forecast() method
> in my Gnuradio OOT block design. I know, if I want to interpolate or
> decimate, I can simply pick the block type in the gr_modtool design menu,
> however, I would like to develop the capability to design my own. Here is
> how I fill in the forecast() method in Python to do either decimation or
> interpolation:
>
> ninput_items_required[0] = noutput_items*self.sps  # for decimation
> OR
> ninput_items_required[0] = noutput_items/self.sps  # for interpolation
>
> On running the flowgraph in GRC Console I see TypeError: 'int' object
> does not support item assignment.
>
> Will appreciate any suggestion to fix this problem.
>
> George
>
>

Problem with the OOT forecast() method in Python

[George Edwards]

Hello GNURadio Community,

I am getting a TypeError when I fill in the code in the forecast() method
in my Gnuradio OOT block design. I know, if I want to interpolate or
decimate, I can simply pick the block type in the gr_modtool design menu,
however, I would like to develop the capability to design my own. Here is
how I fill in the forecast() method in Python to do either decimation or
interpolation:

ninput_items_required[0] = noutput_items*self.sps  # for decimation
OR
ninput_items_required[0] = noutput_items/self.sps  # for interpolation

On running the flowgraph in GRC Console I see TypeError: 'int' object does
not support item assignment.

Will appreciate any suggestion to fix this problem.

George