class NixIOWriteTest(NixIOTest): def setUp(self): self.filename = "nixio_testfile_write.h5" self.writer = NixIO(self.filename, "ow") self.io = self.writer self.reader = nix.File.open(self.filename, nix.FileMode.ReadOnly, backend="h5py") def tearDown(self): self.writer.close() self.reader.close() os.remove(self.filename) def write_and_compare(self, blocks): self.writer.write_all_blocks(blocks) self.compare_blocks(self.writer.read_all_blocks(), self.reader.blocks) self.compare_blocks(blocks, self.reader.blocks) def test_block_write(self): block = Block(name=self.rword(), description=self.rsentence()) self.write_and_compare([block]) block.annotate(**self.rdict(5)) self.write_and_compare([block]) def test_segment_write(self): block = Block(name=self.rword()) segment = Segment(name=self.rword(), description=self.rword()) block.segments.append(segment) self.write_and_compare([block]) segment.annotate(**self.rdict(2)) self.write_and_compare([block]) def test_channel_index_write(self): block = Block(name=self.rword()) chx = ChannelIndex(name=self.rword(), description=self.rsentence(), channel_ids=[10, 20, 30, 50, 80, 130], index=[1, 2, 3, 5, 8, 13]) block.channel_indexes.append(chx) self.write_and_compare([block]) chx.annotate(**self.rdict(3)) self.write_and_compare([block]) chx.channel_names = ["one", "two", "three", "five", "eight", "xiii"] self.write_and_compare([block]) def test_signals_write(self): block = Block() seg = Segment() block.segments.append(seg) asig = AnalogSignal(signal=self.rquant((10, 3), pq.mV), sampling_rate=pq.Quantity(10, "Hz")) seg.analogsignals.append(asig) self.write_and_compare([block]) anotherblock = Block("ir signal block") seg = Segment("ir signal seg") anotherblock.segments.append(seg) irsig = IrregularlySampledSignal( signal=np.random.random((20, 3)), times=self.rquant(20, pq.ms, True), units=pq.A ) seg.irregularlysampledsignals.append(irsig) self.write_and_compare([block, anotherblock]) block.segments[0].analogsignals.append( AnalogSignal(signal=[10.0, 1.0, 3.0], units=pq.S, sampling_period=pq.Quantity(3, "s"), dtype=np.double, name="signal42", description="this is an analogsignal", t_start=45 * pq.ms), ) self.write_and_compare([block, anotherblock]) block.segments[0].irregularlysampledsignals.append( IrregularlySampledSignal(times=np.random.random(10), signal=np.random.random((10, 3)), units="mV", time_units="s", dtype=np.float, name="some sort of signal", description="the signal is described") ) self.write_and_compare([block, anotherblock]) def test_epoch_write(self): block = Block() seg = Segment() block.segments.append(seg) epoch = Epoch(times=[1, 1, 10, 3]*pq.ms, durations=[3, 3, 3, 1]*pq.ms, labels=np.array(["one", "two", "three", "four"]), name="test epoch", description="an epoch for testing") seg.epochs.append(epoch) self.write_and_compare([block]) def test_event_write(self): block = Block() seg = Segment() block.segments.append(seg) event = Event(times=np.arange(0, 30, 10)*pq.s, labels=np.array(["0", "1", "2"]), name="event name", description="event description") seg.events.append(event) self.write_and_compare([block]) def test_spiketrain_write(self): block = Block() seg = Segment() block.segments.append(seg) spiketrain = SpikeTrain(times=[3, 4, 5]*pq.s, t_stop=10.0, name="spikes!", description="sssssspikes") seg.spiketrains.append(spiketrain) self.write_and_compare([block]) waveforms = self.rquant((3, 5, 10), pq.mV) spiketrain = SpikeTrain(times=[1, 1.1, 1.2]*pq.ms, t_stop=1.5*pq.s, name="spikes with wf", description="spikes for waveform test", waveforms=waveforms) seg.spiketrains.append(spiketrain) self.write_and_compare([block]) spiketrain.left_sweep = np.random.random(10)*pq.ms self.write_and_compare([block]) def test_metadata_structure_write(self): neoblk = self.create_all_annotated() self.io.write_block(neoblk) blk = self.io.nix_file.blocks[0] blkmd = blk.metadata self.assertEqual(blk.name, blkmd.name) grp = blk.groups[0] # segment self.assertIn(grp.name, blkmd.sections) grpmd = blkmd.sections[grp.name] for da in grp.data_arrays: # signals name = ".".join(da.name.split(".")[:-1]) self.assertIn(name, grpmd.sections) for mtag in grp.multi_tags: # spiketrains, events, and epochs self.assertIn(mtag.name, grpmd.sections) srcchx = blk.sources[0] # chx self.assertIn(srcchx.name, blkmd.sections) for srcunit in blk.sources: # units self.assertIn(srcunit.name, blkmd.sections) self.write_and_compare([neoblk]) def test_anonymous_objects_write(self): nblocks = 2 nsegs = 2 nanasig = 4 nirrseg = 2 nepochs = 3 nevents = 4 nspiketrains = 3 nchx = 5 nunits = 10 times = self.rquant(1, pq.s) signal = self.rquant(1, pq.V) blocks = [] for blkidx in range(nblocks): blk = Block() blocks.append(blk) for segidx in range(nsegs): seg = Segment() blk.segments.append(seg) for anaidx in range(nanasig): seg.analogsignals.append(AnalogSignal(signal=signal, sampling_rate=pq.Hz)) for irridx in range(nirrseg): seg.irregularlysampledsignals.append( IrregularlySampledSignal(times=times, signal=signal, time_units=pq.s) ) for epidx in range(nepochs): seg.epochs.append(Epoch(times=times, durations=times)) for evidx in range(nevents): seg.events.append(Event(times=times)) for stidx in range(nspiketrains): seg.spiketrains.append(SpikeTrain(times=times, t_stop=times[-1]+pq.s, units=pq.s)) for chidx in range(nchx): chx = ChannelIndex(name="chx{}".format(chidx), index=[1, 2], channel_ids=[11, 22]) blk.channel_indexes.append(chx) for unidx in range(nunits): unit = Unit() chx.units.append(unit) self.writer.write_all_blocks(blocks) self.compare_blocks(blocks, self.reader.blocks) def test_multiref_write(self): blk = Block("blk1") signal = AnalogSignal(name="sig1", signal=[0, 1, 2], units="mV", sampling_period=pq.Quantity(1, "ms")) for idx in range(3): segname = "seg" + str(idx) seg = Segment(segname) blk.segments.append(seg) seg.analogsignals.append(signal) chidx = ChannelIndex([10, 20, 29]) seg = blk.segments[0] st = SpikeTrain(name="choochoo", times=[10, 11, 80], t_stop=1000, units="s") seg.spiketrains.append(st) blk.channel_indexes.append(chidx) for idx in range(6): unit = Unit("unit" + str(idx)) chidx.units.append(unit) unit.spiketrains.append(st) self.writer.write_block(blk) self.compare_blocks([blk], self.reader.blocks) def test_to_value(self): section = self.io.nix_file.create_section("Metadata value test", "Test") writeprop = self.io._write_property # quantity qvalue = pq.Quantity(10, "mV") writeprop(section, "qvalue", qvalue) self.assertEqual(section["qvalue"], 10) self.assertEqual(section.props["qvalue"].unit, "mV") # datetime dt = self.rdate() writeprop(section, "dt", dt) self.assertEqual(datetime.fromtimestamp(section["dt"]), dt) # string randstr = self.rsentence() writeprop(section, "randstr", randstr) self.assertEqual(section["randstr"], randstr) # bytes bytestring = b"bytestring" writeprop(section, "randbytes", bytestring) self.assertEqual(section["randbytes"], bytestring.decode()) # iterables randlist = np.random.random(10).tolist() writeprop(section, "randlist", randlist) self.assertEqual(randlist, section["randlist"]) randarray = np.random.random(10) writeprop(section, "randarray", randarray) np.testing.assert_almost_equal(randarray, section["randarray"]) # numpy item npval = np.float64(2398) writeprop(section, "npval", npval) self.assertEqual(npval, section["npval"]) # number val = 42 writeprop(section, "val", val) self.assertEqual(val, section["val"])
epoch_times = tstart + np.cumsum(np.random.random(3)) * pq.ms epoch = Epoch(name="Seg {} :: Epoch".format(idx), times=epoch_times, durations=np.random.random(4) * pq.ms, labels=["A+", "B+", "C+"]) seg.epochs.append(epoch) st_times = tstart + np.cumsum(np.random.random(10)) * pq.ms tstop = max(event_times[-1], epoch_times[-1], st_times[-1]) + 1 * pq.ms st = SpikeTrain(name="Seg {} :: SpikeTrain".format(idx), times=st_times, t_start=tstart, t_stop=tstop) st.sampling_rate = sampling_rate seg.spiketrains.append(st) unit = Unit(name="unit-{}".format(idx)) unit.spiketrains.append(st) chx.units.append(unit) # Write the Block to file using the NixIO # Any existing file will be overwritten fname = "neoraw.nix" io = NixIO(fname, "ow") io.write_block(block1) io.write_block(block2) io.close() print("Done. Saved to {}".format(fname))
# random sampling times for data_b data_b_t = np.cumsum(np.random.random(1200)) # Create one AnalogSignal and one IrregularlySampledSignal asig_a = AnalogSignal(name="Data A", signal=data_a, units="mV", sampling_rate=pq.Quantity(10, "Hz")) isig_a = IrregularlySampledSignal(name="Sampled data", signal=data_b, units="nA", times=data_b_t, time_units="ms") # Attach the signals to the first segment seg_a.analogsignals.append(asig_a) seg_a.irregularlysampledsignals.append(isig_a) # Create a second AnalogSignal and attach it to the second segment st_a = AnalogSignal(name="Data A", signal=data_c * pq.mV, sampling_rate=20 * pq.Hz) seg_b.analogsignals.append(st_a) # Write the Block to file using the NixIO # Replace NixIO with any other IO to change storage format io = NixIO("example-file.nix", mode='ow') io.write_block(block) io.close()
class NixIOWriteTest(NixIOTest): def setUp(self): self.tempdir = mkdtemp(prefix="nixiotest") self.filename = os.path.join(self.tempdir, "testnixio.nix") self.writer = NixIO(self.filename, "ow") self.io = self.writer self.reader = nix.File.open(self.filename, nix.FileMode.ReadOnly, backend="h5py") def tearDown(self): self.writer.close() self.reader.close() shutil.rmtree(self.tempdir) def write_and_compare(self, blocks): self.writer.write_all_blocks(blocks) self.compare_blocks(blocks, self.reader.blocks) self.compare_blocks(self.writer.read_all_blocks(), self.reader.blocks) self.compare_blocks(blocks, self.reader.blocks) def test_block_write(self): block = Block(name=self.rword(), description=self.rsentence()) self.write_and_compare([block]) block.annotate(**self.rdict(5)) self.write_and_compare([block]) def test_segment_write(self): block = Block(name=self.rword()) segment = Segment(name=self.rword(), description=self.rword()) block.segments.append(segment) self.write_and_compare([block]) segment.annotate(**self.rdict(2)) self.write_and_compare([block]) def test_channel_index_write(self): block = Block(name=self.rword()) chx = ChannelIndex(name=self.rword(), description=self.rsentence(), channel_ids=[10, 20, 30, 50, 80, 130], index=[1, 2, 3, 5, 8, 13]) block.channel_indexes.append(chx) self.write_and_compare([block]) chx.annotate(**self.rdict(3)) self.write_and_compare([block]) chx.channel_names = ["one", "two", "three", "five", "eight", "xiii"] chx.coordinates = self.rquant((6, 3), pq.um) self.write_and_compare([block]) # add an empty channel index and check again newchx = ChannelIndex(np.array([])) block.channel_indexes.append(newchx) self.write_and_compare([block]) def test_signals_write(self): block = Block() seg = Segment() block.segments.append(seg) asig = AnalogSignal(signal=self.rquant((10, 3), pq.mV), sampling_rate=pq.Quantity(10, "Hz")) seg.analogsignals.append(asig) self.write_and_compare([block]) anotherblock = Block("ir signal block") seg = Segment("ir signal seg") anotherblock.segments.append(seg) irsig = IrregularlySampledSignal(signal=np.random.random((20, 3)), times=self.rquant(20, pq.ms, True), units=pq.A) seg.irregularlysampledsignals.append(irsig) self.write_and_compare([block, anotherblock]) block.segments[0].analogsignals.append( AnalogSignal(signal=[10.0, 1.0, 3.0], units=pq.S, sampling_period=pq.Quantity(3, "s"), dtype=np.double, name="signal42", description="this is an analogsignal", t_start=45 * pq.ms), ) self.write_and_compare([block, anotherblock]) block.segments[0].irregularlysampledsignals.append( IrregularlySampledSignal(times=np.random.random(10), signal=np.random.random((10, 3)), units="mV", time_units="s", dtype=np.float, name="some sort of signal", description="the signal is described")) self.write_and_compare([block, anotherblock]) def test_signals_compound_units(self): block = Block() seg = Segment() block.segments.append(seg) units = pq.CompoundUnit("1/30000*V") srate = pq.Quantity(10, pq.CompoundUnit("1.0/10 * Hz")) asig = AnalogSignal(signal=self.rquant((10, 3), units), sampling_rate=srate) seg.analogsignals.append(asig) self.write_and_compare([block]) anotherblock = Block("ir signal block") seg = Segment("ir signal seg") anotherblock.segments.append(seg) irsig = IrregularlySampledSignal(signal=np.random.random((20, 3)), times=self.rquant( 20, pq.CompoundUnit("0.1 * ms"), True), units=pq.CompoundUnit("10 * V / s")) seg.irregularlysampledsignals.append(irsig) self.write_and_compare([block, anotherblock]) block.segments[0].analogsignals.append( AnalogSignal(signal=[10.0, 1.0, 3.0], units=pq.S, sampling_period=pq.Quantity(3, "s"), dtype=np.double, name="signal42", description="this is an analogsignal", t_start=45 * pq.CompoundUnit("3.14 * s")), ) self.write_and_compare([block, anotherblock]) times = self.rquant(10, pq.CompoundUnit("3 * year"), True) block.segments[0].irregularlysampledsignals.append( IrregularlySampledSignal(times=times, signal=np.random.random((10, 3)), units="mV", dtype=np.float, name="some sort of signal", description="the signal is described")) self.write_and_compare([block, anotherblock]) def test_epoch_write(self): block = Block() seg = Segment() block.segments.append(seg) epoch = Epoch(times=[1, 1, 10, 3] * pq.ms, durations=[3, 3, 3, 1] * pq.ms, labels=np.array(["one", "two", "three", "four"]), name="test epoch", description="an epoch for testing") seg.epochs.append(epoch) self.write_and_compare([block]) def test_event_write(self): block = Block() seg = Segment() block.segments.append(seg) event = Event(times=np.arange(0, 30, 10) * pq.s, labels=np.array(["0", "1", "2"]), name="event name", description="event description") seg.events.append(event) self.write_and_compare([block]) def test_spiketrain_write(self): block = Block() seg = Segment() block.segments.append(seg) spiketrain = SpikeTrain(times=[3, 4, 5] * pq.s, t_stop=10.0, name="spikes!", description="sssssspikes") seg.spiketrains.append(spiketrain) self.write_and_compare([block]) waveforms = self.rquant((3, 5, 10), pq.mV) spiketrain = SpikeTrain(times=[1, 1.1, 1.2] * pq.ms, t_stop=1.5 * pq.s, name="spikes with wf", description="spikes for waveform test", waveforms=waveforms) seg.spiketrains.append(spiketrain) self.write_and_compare([block]) spiketrain.left_sweep = np.random.random(10) * pq.ms self.write_and_compare([block]) spiketrain.left_sweep = pq.Quantity(-10, "ms") self.write_and_compare([block]) def test_metadata_structure_write(self): neoblk = self.create_all_annotated() self.io.write_block(neoblk) blk = self.io.nix_file.blocks[0] blkmd = blk.metadata self.assertEqual(blk.name, blkmd.name) grp = blk.groups[0] # segment self.assertIn(grp.name, blkmd.sections) grpmd = blkmd.sections[grp.name] for da in grp.data_arrays: # signals name = ".".join(da.name.split(".")[:-1]) self.assertIn(name, grpmd.sections) for mtag in grp.multi_tags: # spiketrains, events, and epochs self.assertIn(mtag.name, grpmd.sections) srcchx = blk.sources[0] # chx self.assertIn(srcchx.name, blkmd.sections) for srcunit in blk.sources: # units self.assertIn(srcunit.name, blkmd.sections) self.write_and_compare([neoblk]) def test_anonymous_objects_write(self): nblocks = 2 nsegs = 2 nanasig = 4 nirrseg = 2 nepochs = 3 nevents = 4 nspiketrains = 3 nchx = 5 nunits = 10 times = self.rquant(1, pq.s) signal = self.rquant(1, pq.V) blocks = [] for blkidx in range(nblocks): blk = Block() blocks.append(blk) for segidx in range(nsegs): seg = Segment() blk.segments.append(seg) for anaidx in range(nanasig): seg.analogsignals.append( AnalogSignal(signal=signal, sampling_rate=pq.Hz)) for irridx in range(nirrseg): seg.irregularlysampledsignals.append( IrregularlySampledSignal(times=times, signal=signal, time_units=pq.s)) for epidx in range(nepochs): seg.epochs.append(Epoch(times=times, durations=times)) for evidx in range(nevents): seg.events.append(Event(times=times)) for stidx in range(nspiketrains): seg.spiketrains.append( SpikeTrain(times=times, t_stop=times[-1] + pq.s, units=pq.s)) for chidx in range(nchx): chx = ChannelIndex(name="chx{}".format(chidx), index=[1, 2], channel_ids=[11, 22]) blk.channel_indexes.append(chx) for unidx in range(nunits): unit = Unit() chx.units.append(unit) self.writer.write_all_blocks(blocks) self.compare_blocks(blocks, self.reader.blocks) def test_multiref_write(self): blk = Block("blk1") signal = AnalogSignal(name="sig1", signal=[0, 1, 2], units="mV", sampling_period=pq.Quantity(1, "ms")) othersignal = IrregularlySampledSignal(name="i1", signal=[0, 0, 0], units="mV", times=[1, 2, 3], time_units="ms") event = Event(name="Evee", times=[0.3, 0.42], units="year") epoch = Epoch(name="epoche", times=[0.1, 0.2] * pq.min, durations=[0.5, 0.5] * pq.min) st = SpikeTrain(name="the train of spikes", times=[0.1, 0.2, 10.3], t_stop=11, units="us") for idx in range(3): segname = "seg" + str(idx) seg = Segment(segname) blk.segments.append(seg) seg.analogsignals.append(signal) seg.irregularlysampledsignals.append(othersignal) seg.events.append(event) seg.epochs.append(epoch) seg.spiketrains.append(st) chidx = ChannelIndex([10, 20, 29]) seg = blk.segments[0] st = SpikeTrain(name="choochoo", times=[10, 11, 80], t_stop=1000, units="s") seg.spiketrains.append(st) blk.channel_indexes.append(chidx) for idx in range(6): unit = Unit("unit" + str(idx)) chidx.units.append(unit) unit.spiketrains.append(st) self.writer.write_block(blk) self.compare_blocks([blk], self.reader.blocks) def test_no_segment_write(self): # Tests storing AnalogSignal, IrregularlySampledSignal, and SpikeTrain # objects in the secondary (ChannelIndex) substructure without them # being attached to a Segment. blk = Block("segmentless block") signal = AnalogSignal(name="sig1", signal=[0, 1, 2], units="mV", sampling_period=pq.Quantity(1, "ms")) othersignal = IrregularlySampledSignal(name="i1", signal=[0, 0, 0], units="mV", times=[1, 2, 3], time_units="ms") sta = SpikeTrain(name="the train of spikes", times=[0.1, 0.2, 10.3], t_stop=11, units="us") stb = SpikeTrain(name="the train of spikes b", times=[1.1, 2.2, 10.1], t_stop=100, units="ms") chidx = ChannelIndex([8, 13, 21]) blk.channel_indexes.append(chidx) chidx.analogsignals.append(signal) chidx.irregularlysampledsignals.append(othersignal) unit = Unit() chidx.units.append(unit) unit.spiketrains.extend([sta, stb]) self.writer.write_block(blk) self.compare_blocks([blk], self.reader.blocks) self.writer.close() reader = NixIO(self.filename, "ro") blk = reader.read_block(neoname="segmentless block") chx = blk.channel_indexes[0] self.assertEqual(len(chx.analogsignals), 1) self.assertEqual(len(chx.irregularlysampledsignals), 1) self.assertEqual(len(chx.units[0].spiketrains), 2) def test_to_value(self): section = self.io.nix_file.create_section("Metadata value test", "Test") writeprop = self.io._write_property # quantity qvalue = pq.Quantity(10, "mV") writeprop(section, "qvalue", qvalue) self.assertEqual(section["qvalue"], 10) self.assertEqual(section.props["qvalue"].unit, "mV") # datetime dt = self.rdate() writeprop(section, "dt", dt) self.assertEqual(datetime.fromtimestamp(section["dt"]), dt) # string randstr = self.rsentence() writeprop(section, "randstr", randstr) self.assertEqual(section["randstr"], randstr) # bytes bytestring = b"bytestring" writeprop(section, "randbytes", bytestring) self.assertEqual(section["randbytes"], bytestring.decode()) # iterables randlist = np.random.random(10).tolist() writeprop(section, "randlist", randlist) self.assertEqual(randlist, section["randlist"]) randarray = np.random.random(10) writeprop(section, "randarray", randarray) np.testing.assert_almost_equal(randarray, section["randarray"]) # numpy item npval = np.float64(2398) writeprop(section, "npval", npval) self.assertEqual(npval, section["npval"]) # number val = 42 writeprop(section, "val", val) self.assertEqual(val, section["val"]) # empty string writeprop(section, "emptystring", "") self.assertEqual("", section["emptystring"]) def test_annotations_special_cases(self): # Special cases for annotations: empty list, list of strings, # multidimensional lists/arrays # These are handled differently on read, so we test them on a block # instead of just checking the property writer method # empty value # empty list wblock = Block("block with empty list", an_empty_list=list()) self.writer.write_block(wblock) rblock = self.writer.read_block(neoname="block with empty list") self.assertEqual(rblock.annotations["an_empty_list"], list()) # empty tuple (gets read out as list) wblock = Block("block with empty tuple", an_empty_tuple=tuple()) self.writer.write_block(wblock) rblock = self.writer.read_block(neoname="block with empty tuple") self.assertEqual(rblock.annotations["an_empty_tuple"], list()) # list of strings losval = ["one", "two", "one million"] wblock = Block("block with list of strings", los=losval) self.writer.write_block(wblock) rblock = self.writer.read_block(neoname="block with list of strings") self.assertEqual(rblock.annotations["los"], losval)
def create_nix_file(file_pat, output=None, signed=False, rate=1, electrode_scale=0.0104, analog_scale=12.5122, channels=channels, chunks=256 * 1024 * 1024): '''The default resolution (i.e. voltage per bit) in uV ''' filenames = sorted(glob(file_pat)) dtype = np.int16 if signed else np.uint16 N = len(channels) slice_size = N * 2 chunks = chunks - chunks % slice_size # round to equal blocks reader = read_files(filenames, dtype, chunks, slice_size) data = next(reader) if signed: af = lambda x: x.astype(np.float32) * analog_scale ef = lambda x: x.astype(np.float32) * electrode_scale df = lambda x: np.array(x, dtype=np.bool_) else: af = lambda x: (x.astype(np.float32) - 2**15) * analog_scale ef = lambda x: (x.astype(np.float32) - 2**15) * electrode_scale df = lambda x: np.array(x.astype(np.int32) - 2**15, dtype=np.bool_) analogs = [(i, ch) for i, ch in enumerate(channels) if ch.startswith('A')] digitals = [(i, ch) for i, ch in enumerate(channels) if ch.startswith('D')] electrodes = [(i, ch) for i, ch in enumerate(channels) if not ch.startswith('D') and not ch.startswith('A')] groups = (('Analog', analogs, af, np.float32), ('Digital', digitals, df, np.bool_), ('Electrodes', electrodes, ef, np.float32)) if output is None: output = '{}.h5'.format(splitext(filenames[0])[0]) ofile = NixIO(output, mode='ow') blk = Block() for group_name, channels, f, dtype in groups: seg = Segment(name=group_name) for slice_idx, chan_name in channels: seg.analogsignals.append( AnalogSignal(f(data[slice_idx::N]), dtype=dtype, units=uV, sampling_rate=rate * Hz, name=chan_name)) blk.segments.append(seg) ofile.write_block(blk) nix_file = ofile.nix_file nix_groups = nix_file.blocks[0].groups for data in reader: for k, (group_name, channels, f, _) in enumerate(groups): data_arrays = nix_groups[k].data_arrays for i, (slice_idx, _) in enumerate(channels): # nix_file._h5file.flush() data_arrays[i].append(f(data[slice_idx::N])) nix_file.close() return output