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

[Josh Blum]

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
>>
> 
> 
>