Re: [Discuss-gnuradio] Read/Write stream tags in Python

[Anisha Gorur]

Also, I've been assuming that nitems_written/read is from gr_block_detail, and add_item_tag is from gr_block and that they have both been swigged, since you used them in your example. Is it possible that they haven't been? 

Thanks
-Anisha

On Fri, Jul 13, 2012 at 3:57 PM, Anisha Gorur <address@hidden> wrote:

I don't think I'm writing the work function...

def work(self, input_items, output_items):
        item_index = 1 #which output item gets the tag?

        offset =  self.nitems_written(0) + item_index
        key = pmt.pmt_string_to_symbol("example_key")
        value = pmt.pmt_string_to_symbol("example_value")

        self.add_item_tag(0, offset, key, value)
#call work function
self.work(self.gr_vector_source_x_0, self.gr_file_sink_0)

Error: AttributeError: 'gr_top_block_sptr' object has no attribute 'nitems_written'

On Fri, Jul 13, 2012 at 3:25 PM, Josh Blum <address@hidden> wrote:

On 07/13/2012 12:08 PM, Anisha Gorur wrote:
> Thanks for the examples, I will definitely be looking into them!
> As for links, This one: http://gnuradio.org/cgit/jblum.git/log/?h=next is
> broken, it comes from one of the blocks coding guide here:
> http://gnuradio.org/redmine/projects/gnuradio/wiki/BlocksCodingGuide/diff/2which
> i found really helpful.
>

There was a lot of work in various branches off of gnuradio which I had
merged into next. That branch is gone, and that work has been combined
into the GrExtras project. The link and relevant coding guide was
moved/updated: https://github.com/guruofquality/grextras/wiki

> I also had one more quick question, I'm getting this error:
> 'gr_top_block_sptr' object has no attribute 'add_item_tag', though I
> thought add_item_tag was inherited from gr_block.
> Thanks again!
>

Not sure, you might send a code snippet. It looks like you are calling a
method of the top block, and not from the block's work function?

-josh

> On Fri, Jul 13, 2012 at 2:40 PM, Josh Blum <address@hidden> wrote:
>
>>
>>
>> On 07/13/2012 10:08 AM, Anisha Gorur wrote:
>>> Thanks!
>>> Do you by any chance have links to specific code examples that could help
>>> out? I've been trying to look at old examples you have posted to others
>> on
>>> this forum, however, some of the links from github seem to be broken.
>>>
>>
>> Well, I dont have an example from python, but its just the same thing
>> without semicolons. So this should be very helpful:
>> http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/examples/c++/
>>
>> Let me know if the links are bad on one of my wiki pages.
>> At least I can fix those :-)
>>
>> -josh
>>
>>> On Fri, Jul 13, 2012 at 12:52 PM, Josh Blum <address@hidden> wrote:
>>>
>>>>
>>>>
>>>> On 07/13/2012 08:51 AM, Anisha Gorur wrote:
>>>>> Hello all,
>>>>> I've been trying to work with stream tags in python, mainly using the
>>>>> grextras blocks coding guide
>>>>> here:https://github.com/guruofquality/grextras/wiki/Blo...
>>>>> <
>>>>
>> https://github.com/guruofquality/grextras/wiki/Blocks-Coding-Guide#wiki-the-work-function
>>>>> .
>>>>>
>>>>> I've set up a very simple flow graph, just a vector source, throttle
>> and
>>>>> file sink, and I would like to place a tag on the first element of the
>>>>> vector that contains time metadata. I'm using this code:
>>>>>
>>>>> def work(self, input_items, output_items):
>>>>> item_index = ? #which output item gets the tag?
>>>>
>>>> set item_index to x so the tag gets associated with outputs_items[0][x]
>>>>
>>>>> offset = self.nitems_written(0) + item_index
>>>>> key = pmt.pmt_string_to_symbol("example_key")
>>>>> value = pmt.pmt_string_to_symbol("example_value")
>>>>>
>>>>> #write at tag to output port 0 with given absolute item offset
>>>>> self.add_item_tag(0, offset, key, value)
>>>>>
>>>>> I think the problem has something to do with not implementing the
>>>>> correct modules. My question is, what are the appropriate modules to
>>>>> import to read and write stream tags in python?
>>>>>
>>>>
>>>> You might want to look more that that coding guide, at lot of the
>>>> snippets are just work functions, but many contain full class
>>>> definitions with import statements. For example:
>>>>
>>>> from gnuradio import gr
>>>> import gnuradio.extras
>>>>
>>>> class my_sync_block(gr.block):
>>>>
>>>>     def __init__(self, args):
>>>>         gr.block.__init__(self, name="my block", in_sig=[numpy.int32],
>>>> out_sig=[numpy.int32])
>>>>
>>>>     def work(self, input_items, output_items):
>>>>         #work stuff...
>>>>         return len(output_items[0])
>>>>
>>>> -josh
>>>>
>>>> _______________________________________________
>>>> Discuss-gnuradio mailing list
>>>> address@hidden
>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>>
>>>
>>>
>>>
>>
>>
>
>

--
Anisha Gorur
Class of 2012
Electrical Engineering

-- 
Anisha Gorur
Class of 2012
Electrical Engineering