stimuli: retain provenance in playlist when play_item

ref: #16

be consistent with the playlist case and set the producer_playlist_n
field also when extracting the single `AudioStim.data_generator`
via `Playlist.play_item`

flyvr/audio/stimuli.py

@@ -150,15 +150,17 @@ def describe(self):
                 'max_value': self.__max_value,
                 'min_value': self.__min_value}
 
-    def data_generator(self, producer_instance_n_override=None) -> Iterator[Optional[SampleChunk]]:
+    def data_generator(self, producer_instance_n_override=None, producer_playlist_n_override=None) -> Iterator[Optional[SampleChunk]]:
         """
         Return a generator that yields the data member when next is called on it. Simply provides another interface to
         the same data stored in the data member.
         """
         while True:
             self.num_samples_generated = self.num_samples_generated + self.data.shape[0]
             chunk = SampleChunk(data=self.data, producer_identifier=self.identifier,
-                                producer_instance_n=producer_instance_n_override or self.producer_instance_n)
+                                producer_instance_n=producer_instance_n_override if producer_instance_n_override is not None else self.producer_instance_n,
+                                producer_playlist_n=producer_playlist_n_override if producer_playlist_n_override is not None else -1)
+
             self.trigger_next_callback(chunk)
             yield chunk
 
@@ -865,16 +867,17 @@ def from_playlist_definition(cls, stim_playlist, basedirs, paused_fallback, defa
                              attenuator=attenuator)
 
     def play_item(self, identifier):
-        for stim in self._stims:
+        for n, stim in enumerate(self._stims):
             if stim.identifier == identifier:
                 SignalProducer.instances_created += 1
-                return stim.data_generator(-100 - SignalProducer.instances_created)
+                return stim.data_generator(producer_instance_n_override=-100 - SignalProducer.instances_created,
+                                           producer_playlist_n_override=n)
         raise ValueError('%s not found' % identifier)
 
     def play_pause(self, pause):
         self.paused = pause
 
-    def data_generator(self, producer_instance_n_override=None) -> Iterator[Optional[SampleChunk]]:
+    def data_generator(self) -> Iterator[Optional[SampleChunk]]:
         """
         Return a generator that yields each AudioStim in the playlist in succession. If shuffle_playback is set to true
         then we will get a non-repeating randomized sequence of all stimuli, then they will be shuffled, and the process

tests/audio/test_samplechunks.py

@@ -318,26 +318,31 @@ def test_play_item_produces_new_instance_chunk(stimplaylist):
     # array in a loop, aka from the same chunk producer
     ca0 = next(a)
     assert ca0.producer_identifier == 'sin10hz'
+    assert ca0.producer_playlist_n == 0
     assert ca0.data.shape == (1200,)
     ca1 = next(a)
     assert ca1.data.shape == (1200,)
     assert ca1.producer_identifier == 'sin10hz'
+    assert ca1.producer_playlist_n == 0
     assert not chunk_producers_differ(ca0, ca1)
     ca2 = next(a)
     assert ca2.data.shape == (1200,)
     assert ca2.producer_identifier == 'sin10hz'
+    assert ca2.producer_playlist_n == 0
     assert not chunk_producers_differ(ca0, ca2)
 
     # first chunk on different AudioStim from the previous play_item
     cb0 = next(b)
     assert cb0.data.shape == (1200,)
     assert cb0.producer_identifier == 'constant1'
+    assert cb0.producer_playlist_n == 1
     assert chunk_producers_differ(ca0, cb0)
 
     # first chunk on same AudioStim from the first sin10hz
     cc0 = next(c)
     assert cc0.data.shape == (1200,)
     assert cc0.producer_identifier == 'sin10hz'
+    assert cc0.producer_playlist_n == 0
     assert chunk_producers_differ(ca0, cc0)
 
 
@@ -348,35 +353,42 @@ def test_play_item_produces_new_instance_chunk_chunker(stimplaylist):
 
     ca0 = next(a)
     assert ca0.producer_identifier == 'sin10hz'
+    assert ca0.producer_playlist_n == 0
     assert ca0.data.shape == (600,)
     ca1 = next(a)
     assert ca1.producer_identifier == 'sin10hz'
+    assert ca1.producer_playlist_n == 0
     assert ca1.data.shape == (600,)
     assert not chunk_producers_differ(ca0, ca1)
     # loops back round to the start
     ca2 = next(a)
     assert ca2.producer_identifier == 'sin10hz'
+    assert ca2.producer_playlist_n == 0
     assert ca2.data.shape == (600,)
     assert not chunk_producers_differ(ca1, ca2)
     assert not chunk_producers_differ(ca0, ca2)
 
     cb0 = next(b)
     assert cb0.producer_identifier == 'constant1'
+    assert cb0.producer_playlist_n == 1
     assert cb0.data.shape == (600,)
 
     assert chunk_producers_differ(ca0, cb0)
     assert chunk_producers_differ(ca2, cb0)
 
     cc0 = next(c)
     assert cc0.producer_identifier == 'sin10hz'
+    assert cc0.producer_playlist_n == 0
     assert cc0.data.shape == (600,)
     cc1 = next(c)
     assert cc1.producer_identifier == 'sin10hz'
+    assert cc1.producer_playlist_n == 0
     assert cc1.data.shape == (600,)
     assert not chunk_producers_differ(cc0, cc1)
     # loops back round to the start
     cc2 = next(c)
     assert cc2.producer_identifier == 'sin10hz'
+    assert cc2.producer_playlist_n == 0
     assert cc2.data.shape == (600,)
     assert not chunk_producers_differ(cc1, cc2)
     assert not chunk_producers_differ(cc0, cc2)