Argh, sorry, to_float returns a float64, which of course means that
Python's file.write is a bit confused by this request, and it's getting
late :/ concentration used to be better.
So, add
import struct
where the other imports are.
Then,
self._file.write(struct.pack("d", pmt.to_float(msg) ) )
should
1. get the 64 bit float from the pmt message,
2. pack that into a string object according to the format "d" (which
simply says, take a single double and give it to me as raw 8 bytes)
3. writes that to the file.
Best regards,
Marcus
On 19.02.2016 00:05, Richard Bell wrote:
> Sorry Marcus, I'm not familiar with pmts and message passing things to
> handle these errors on my own. When I change
> "self._file.write(pmt.serialize_str(msg))" to
> "self._file.write(pmt.to_float(msg))", I get the following error in
> grc terminal
>
> handler caught exception: expected a character buffer object
> Traceback (most recent call last):
> File
> "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gateway.py", line
> 73, in eval
> try: self._callback(arg)
> File
> "/usr/local/lib/python2.7/dist-packages/msgtools/msg_file_sink.py",
> line 41, in _msg_handler
> self._file.write(pmt.to_float(msg))
> TypeError: expected a character buffer object
> thread[thread-per-block[101]: <block msg_file_sink (47)>]: caught
> unrecognized exception
>
> Thanks for the help.
>
> Rich
>
> On Thu, Feb 18, 2016 at 2:55 PM, Marcus Müller
> <[email protected] <mailto:[email protected]>> wrote:
>
> Ah, sorry, no, the block just takes the raw serialized pmt and
> writes it to a file [1]:
>
> self._file.write(pmt.serialize_str(msg))
>
> You could use python with pmt module to unserialize, but:
>
> if you just replace "serialize_str" with "to_float", this should
> give you what you expect. Notice this is really just experimental;
> copy the block to your own code. I'll probably rewrite as
> something in C++ to make it useful on platforms without python, too.
>
> Cheers,
> Marcus
>
> [1]
>
> https://github.com/marcusmueller/gr-msgtools/blob/master/python/msg_file_sink.py#L41
>
>
>
> On 18.02.2016 23:13, Richard Bell wrote:
>> I just tested it. I expect to see log scale values of SNR coming
>> out of the estimator block. When I look at this directly using a
>> function_probe and qt_gui_label in grc, I see proper estimates.
>> When I load the file produced by the msg_file_snk into octave, I
>> see incorrect values ranging from e-40 to e+40. I assumed the
>> msg_file_snk stored values as float, so I used the
>> read_float_binary.m script on the file to plot. Are we having a
>> type conversion issue here?
>>
>> Rich
>>
>> On Thu, Feb 18, 2016 at 1:33 PM, Marcus Müller
>> <[email protected] <mailto:[email protected]>> wrote:
>>
>> Sorry, I forgot to git push; could you git pull?
>>
>> On 02/18/2016 10:27 PM, Richard Bell wrote:
>>> There is only one block in your git, Variable To Message,
>>> and no built in Message File Sink in GR. I'm using gr
>>> 3.7.10. How did you see this being used?
>>>
>>> Rich
>>>
>>> On Thu, Feb 18, 2016 at 1:12 PM, Richard Bell
>>> <[email protected] <mailto:[email protected]>>
>>> wrote:
>>>
>>> Excellent thanks.
>>>
>>> Rich
>>>
>>> On Thu, Feb 18, 2016 at 1:09 PM, Marcus Müller
>>> <[email protected]
>>> <mailto:[email protected]>> wrote:
>>>
>>> Sorry, took a while longer, juggling multiple mails:
>>> https://github.com/marcusmueller/gr-msgtools
>>>
>>> use the msg_file_sink :)
>>>
>>>
>>> On 02/18/2016 09:35 PM, Marcus Müller wrote:
>>>> From the top of my head, there's nothing that does
>>>> that... yet.
>>>> Let's see if I can hack together something in
>>>> python that does that. Gimme a second.
>>>>
>>>> On 02/18/2016 09:22 PM, Richard Bell wrote:
>>>>> I want to store the output SNR measurement
>>>>> messages of the MPSK SNR Estimator Probe to a
>>>>> file, but I'm not sure how to transform async
>>>>> messages to a stream to get them into a file.
>>>>> Would someone please recommend a method of doing
>>>>> this in GRC.
>>>>>
>>>>> Rich
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Discuss-gnuradio mailing list
>>>>> [email protected]
>>>>> <mailto:[email protected]>
>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>>
>>>
>>>
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>>>
>>
>>
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>>
>>
>
>
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