def write_ordered(fin, df, fout):
'''Writes out a vdif file according to the order of DataFrame df
'''
with vdif.open(fin, 'rb') as fr, vdif.open(fout, 'wb') as fw:
for r in df.itertuples():
fr.seek(r.offset)
frame = fr.read_frame(edv=2, verify=False)
fw.write_frame(frame)
def split(f, delta_t=1, nfiles=None):
with vdif.open(f, 'rb') as fr:
fw = None
previous_second = None
starting_second = None
basename = None
while True:
try:
frame = fr.read_frame(edv=2, verify=False)
except EOFError as e:
print('saw exception {} in {}, terminating'.format(
e, basename),
file=sys.stderr)
return
except Exception as e:
print('saw exception {}, skipping frame'.format(e),
file=sys.stderr)
continue
seconds = frame.header['seconds']
if frame.header['invalid_data']:
fw.write_frame(frame)
continue
if starting_second is None:
starting_second = seconds
if previous_second is None or seconds >= previous_second + delta_t:
if nfiles is not None:
if nfiles == 0:
break
nfiles -= 1
previous_second = seconds
#head, tail = os.path.split(f)
#basename, ext = os.path.splitext(tail)
basename, ext = os.path.splitext(
f) # write output in the same directory as input
new = basename + '-' + str(seconds - starting_second) + ext
if os.path.isfile(new):
raise ValueError(new + ' already exists')
fw = vdif.open(new, 'wb')
print('t={} file {}'.format(seconds, new))
if seconds < previous_second:
print('input was not strictly sorted by time: saw {} after {}'.
format(seconds, previous_second),
file=sys.stderr)
fw.write_frame(frame)
def setup(self):
self._fh = vdif.open(SAMPLE_VDIF)
self.fh = SetAttribute(self._fh,
frequency=311.25 * u.MHz +
(np.arange(8.) // 2) * 16. * u.MHz,
sideband=np.array(1),
polarization=np.tile(['L', 'R'], 4))
def test_missing_frequency_sideband(self):
fh = vdif.open(SAMPLE_VDIF)
with Channelize(fh, self.n) as ct:
with pytest.raises(AttributeError):
ct.frequency
with pytest.raises(AttributeError):
ct.sideband
def test_function_tasks(self, task, sample_factor):
"""Test setting a channel to zero."""
# Load baseband file and get reference intensities.
fh = vdif.open(SAMPLE_VDIF)
ref_data = task(fh.read())
ft = Task(fh, task, sample_rate=fh.sample_rate * sample_factor)
assert ft.shape[0] == fh.shape[0] * sample_factor
# Apply to everything.
data1 = ft.read()
assert ft.tell() == ft.shape[0]
assert (ft.time - ft.start_time -
ft.shape[0] / ft.sample_rate) < 1*u.ns
assert ft.dtype is ref_data.dtype is data1.dtype
assert np.allclose(ref_data, data1)
# Seeking and selective zeroing.
ft.seek(-3, 2)
assert ft.tell() == ft.shape[0] - 3
data2 = ft.read()
assert data2.shape[0] == 3
assert np.allclose(ref_data[-3:], data2)
ft.close()
def get_multifile_data(vbs, nif):
vbsname = vbs + "_" + str(nif)
disk2fileout = scriptdir + "/checkdata.vdif"
ss = fbcmd("scan_set=" + vbsname + ":+2.0s:+" + extractiontime)
if " does not exist" in ss:
return [-1, 0, -1]
sc = fbcmd("scan_check?")
nbbcs = int(int(sc.split(":")[4]) / 2)
fbcmd("disk2file=" + disk2fileout + ":::w")
nwait = 0
time.sleep(0.25) # Wait for disk2file
while True:
stat = fbcmd("disk2file?")
if "inactive" in stat:
break
if nwait > 5:
print(
"ERROR: Waited more than 5 sec for disk2file! Something is wrong, exiting..."
)
sys.exit(1)
time.sleep(1) # Wait for disk2file
nwait += 1
# Read file
fh = vdif.open(
disk2fileout, 'rs', sample_rate=sample_rate *
u.MHz) # Need to specify sample rate, too short to autodetect.
start_time = fh.info()['start_time']
# Ensure file pointer is at beginning of file
fh.seek(0)
# Read all data until end
ifdata = fh.read()
# Close infile
fh.close()
return [nbbcs, ifdata, start_time]
def test_channelizetask(self):
"""Test channelization task."""
fh = vdif.open(SAMPLE_VDIF)
ct = Channelize(fh, self.n)
# Channelize everything.
data1 = ct.read()
assert ct.tell() == ct.shape[0]
assert (ct.time - ct.start_time -
ct.shape[0] / ct.sample_rate) < 1*u.ns
assert ct.dtype is self.ref_data.dtype is data1.dtype
assert np.all(self.ref_data == data1)
# Seeking and selective decode.
ct.seek(-3, 2)
assert ct.tell() == ct.shape[0] - 3
data2 = ct.read()
assert data2.shape[0] == 3
assert np.all(self.ref_data[-3:] == data2)
ct.seek(-2, 2)
with pytest.raises(EOFError):
ct.read(10)
# Quick test of channel sanity check in __init__.
with pytest.raises(AssertionError):
ct = Channelize(fh, 400001)
ct.close()
def test_wrong_polarization_vdif(self):
with vdif.open(SAMPLE_VDIF) as fh:
with pytest.raises(AttributeError):
Power(fh)
fh.polarization = np.array(['L', 'R'] * 4)
with pytest.raises(ValueError): # Too many.
Power(fh)
def test_taskbase(self, n, samples_per_frame):
"""Test properties and methods of TaskBase, including
self-consistency with varying ``n`` and ``samples_per_frame``.
"""
fh = vdif.open(SAMPLE_VDIF)
rt = ReshapeTime(fh, n, samples_per_frame=samples_per_frame)
# Check sample pointer.
assert rt.sample_rate == fh.sample_rate / n
nsample = samples_per_frame * (fh.shape[0] // n // samples_per_frame)
assert rt.shape == (nsample, n) + fh.sample_shape
assert rt.size == np.prod(rt.shape)
assert rt.ndim == fh.ndim + 1
assert rt.tell() == 0
assert rt.tell(unit='time') == rt.time == rt.start_time
assert abs(rt.stop_time - rt.start_time -
(nsample * n) / fh.sample_rate) < 1*u.ns
# Get reference data.
ref_data = fh.read(nsample * n).reshape((-1, n) + fh.sample_shape)
# Check sequential reading.
data1 = rt.read()
assert rt.tell() == rt.shape[0]
assert abs(rt.time - rt.start_time -
rt.shape[0] / rt.sample_rate) < 1*u.ns
assert rt.dtype is data1.dtype
assert np.all(ref_data == data1)
# Check seeking and selective decode.
rt.seek(-7, 2)
assert rt.tell() == rt.shape[0] - 7
data2 = rt.read()
assert data2.shape[0] == 7
assert np.all(data2 == ref_data[-7:])
sec_offset = -0.25 * u.ms
rt.seek(sec_offset, 'end')
assert rt.tell() == rt.shape[0] + self.convert_time_offset(
sec_offset, rt.sample_rate)
assert rt.tell(unit=u.ms) == (rt.tell() / rt.sample_rate).to(u.ms)
current_offset = rt.tell()
rt.seek(2, 'current')
assert rt.tell() == current_offset + 2
time_offset = rt.start_time + 0.13 * u.ms
rt.seek(time_offset, 'start')
assert rt.tell() == self.convert_time_offset(
time_offset - rt.start_time, rt.sample_rate)
# Check reading to external array.
out = np.empty((11,) + rt.sample_shape)
rt.seek(0)
rt.read(out=out)
assert np.all(out == ref_data[:11])
# Check closing.
rt.close()
assert fh.closed
with pytest.raises(ValueError):
rt.read(1)
def test_wrong_axes(self):
with vdif.open(SAMPLE_VDIF) as fh:
with pytest.raises(ValueError):
self.get_reshape_and_transpose(fh, (4, 2), (1, 0))
with pytest.raises(ValueError):
self.get_reshape_and_transpose(fh, (4, 2), (2, 3))
with pytest.raises(ValueError):
self.get_reshape_and_transpose(fh, (4, 2), (1, 1))
def get_fh():
"""Get sample VDIF file with correct frequency, sideband, polarization."""
fh = vdif.open(SAMPLE_VDIF)
# Add frequency, sideband, and polarization information by hand.
fh.frequency = 311.25 * u.MHz + (np.arange(8.) // 2) * 16. * u.MHz
fh.sideband = 1
fh.polarization = np.tile(['L', 'R'], 4)
return fh
def test_frequency_sideband_propagation(self):
fh = vdif.open(SAMPLE_VDIF)
# Add frequency and sideband information by hand.
# (Note: sideband is incorrect; just for testing purposes)
fh.frequency = 311.25 * u.MHz + (np.arange(8.) // 2) * 16. * u.MHz
fh.sideband = np.tile([-1, +1], 4)
rt = ReshapeTime(fh, 256)
assert np.all(rt.sideband == fh.sideband)
assert np.all(rt.frequency == fh.frequency)
def test_missing_frequency_sideband_polarization(self):
fh = vdif.open(SAMPLE_VDIF)
st = Square(fh)
with pytest.raises(AttributeError):
st.frequency
with pytest.raises(AttributeError):
st.sideband
with pytest.raises(AttributeError):
st.polarization
def test_basic(self):
fh = vdif.open(SAMPLE_VDIF)
ref_data = fh.read().reshape((-1, 4, 2)).transpose(0, 2, 1)
tt = self.get_reshape_and_transpose(fh, (4, 2), (2, 1))
assert tt.start_time == fh.start_time
assert tt.sample_rate == fh.sample_rate
data = tt.read()
assert_array_equal(data, ref_data)
tt.close()
def test_frequency_sideband_setting(self):
fh = vdif.open(SAMPLE_VDIF)
# Add frequency and sideband information by hand, broadcasting it.
# (Note: sideband is incorrect; just for testing purposes)
frequency_in = 311.25 * u.MHz + (np.arange(8.) // 2) * 16. * u.MHz
sideband_in = np.tile([-1, +1], 4)
rt = ReshapeTime(fh, 256, frequency=frequency_in, sideband=sideband_in)
assert np.all(rt.sideband == sideband_in)
assert np.all(rt.frequency == frequency_in)
def test_invalid(self):
fh = vdif.open(SAMPLE_VDIF)
with pytest.raises(ValueError):
SquareHat(fh, -1)
with pytest.raises(ValueError):
SquareHat(fh, 10, offset=-1)
with pytest.raises(ValueError):
SquareHat(fh, 10, samples_per_frame=9)
with warnings.catch_warnings(record=True) as w:
SquareHat(fh, 10, samples_per_frame=11)
assert any('inefficient' in str(_w) for _w in w)
def test_frequency_sideband_propagation(self):
fh = vdif.open(SAMPLE_VDIF)
# Add frequency and sideband information by hand.
# (Note: sideband is incorrect; just for testing purposes)
fh.frequency = 311.25 * u.MHz + (np.arange(8.) // 2) * 16. * u.MHz
fh.sideband = np.tile([-1, +1], 4)
fh.polarization = np.tile(['L', 'R'], 4)
st = Square(fh)
assert np.all(st.frequency == fh.frequency)
assert np.all(st.sideband == fh.sideband)
assert np.all(st.polarization == np.tile(['LL', 'RR'], 4))
def test_method_task(self, samples_per_frame):
fh = vdif.open(SAMPLE_VDIF)
count = fh.shape[0]
if samples_per_frame is not None:
count = (count // samples_per_frame) * samples_per_frame
ref_data = zero_every_8th_sample(fh.read(count))
with Task(fh, zero_every_8th_complex,
samples_per_frame=samples_per_frame) as ft:
data1 = ft.read()
assert np.all(data1 == ref_data)
def test_wrong_polarization(self):
fh = dada.open(SAMPLE_DADA)
with pytest.raises(ValueError):
Power(fh, polarization=['L'])
with pytest.raises(ValueError):
Power(fh, polarization=[['L'], ['R']])
with pytest.raises(ValueError):
Power(fh, polarization=[['L'], ['L']])
fh = vdif.open(SAMPLE_VDIF)
with pytest.raises(ValueError):
Power(fh)
def test_basics(self):
fh = vdif.open(SAMPLE_VDIF)
sh = SquareHat(fh, 3)
expected_size = ((fh.shape[0] - 2) // 4) * 4
assert sh.sample_rate == fh.sample_rate
assert sh.shape == (expected_size,) + fh.shape[1:]
assert abs(sh.start_time - fh.start_time -
2. / fh.sample_rate) < 1. * u.ns
raw = fh.read(12)
expected = raw[:-2] + raw[1:-1] + raw[2:]
data = sh.read(10)
assert np.all(data == expected)
def open(self, fname):
"""Open data with appropriate baseband reader"""
if self.dtype == 'vdif':
self.fh = vdif.open(fname, mode='rs', sample_rate=self.sample_rate)
if self.dtype == 'mark4':
self.fh = mark4.open(fname, mode='rs', decade=2010, ntrack=self.ntrack,
sample_rate=self.sample_rate, thread_ids=self.thread_ids)
if self.dtype == 'mark5b':
self.fh = mark5b.open(fname, mode='rs', nchan=self.nIF, ref_mjd=57000,
sample_rate=self.sample_rate, thread_ids=self.thread_ids)
def test_reshape(self, sample_shape):
fh = vdif.open(SAMPLE_VDIF)
ref_data = fh.read().reshape((-1, ) + sample_shape)
rt = Reshape(fh, sample_shape=sample_shape)
assert fh.sample_shape == (8, )
assert rt.sample_shape == sample_shape
assert rt.start_time == fh.start_time
assert rt.sample_rate == fh.sample_rate
data = rt.read()
assert_array_equal(data, ref_data)
rt.close()
def read_vdif(vdif_files, sample_rate, max=2**15):
"""
Reads the data from vdif_files. Sets up self.background, self.NFREQ,
and self.NTIME. Will handle the cases where vdif_files is a single
vdif_file and the cases where vdir_files is a list of files. If there
is more than 2**15 samples contained in vdif_files, the data will be
binned in the time dimension to reduce the size of the data.
Args:
vdif_files (list or str): The path to the vdif file to be read, or a
list of paths to different vdif files to be
read. If a list is given the vdifs will be
opened in the order they are given in the
list.
sample_rate (Quantity): The sampling rate of the vdifs.
max (int): The upper limit on final # of samples to
contain the data in. The largest factor of
the number of samples in vdif_files <= max
will be the actual size of the data. If
there are no factors of the number of
samples less than max than the data will
not be binned.
Returns:
background (ndarray): The data contained in the vdifs.
files (str): The names of the vdif files with prefix/suffix
removed, joined by dashes.
"""
try:
temp = vdif_files.split() # Will split if str, fail if list
vdif_files = [vdif_files] # Convert to a list with 1 element
except AttributeError:
pass # Do nothing because vdif_files is already a list
vdif_files = sf.open(vdif_files)
with vdif.open(vdif_files, 'rs', sample_rate=sample_rate) as fh:
# if fh.shape[0] > max: # Read data in chunks, reduce size to be <= max
# complete_data, new_rate = chunk_read(fh, max, sample_rate)
# else: # Read data all at once
complete_data = fh.read()
# Get the power from data
complete_data = (np.abs(complete_data)**2).mean(1)
complete_data -= np.nanmean(complete_data, axis=1, keepdims=True)
complete_data = complete_data.T
new_rate = sample_rate
# Get the input filenames without their path or suffix
files = vdif_files.files
files = ['.'.join(x.split('/')[-1].split('.')[:-1]) for x in files]
file_names = '-'.join(files)
return complete_data, file_names, new_rate
def __init__(self,
raw_files,
blocksize,
samplerate,
fedge,
fedge_at_top,
time_offset=0.0 * u.s,
dtype='cu4bit,cu4bit',
comm=None):
"""ARO data acquired with a CHIME correlator, saved in VDIF format.
Files are 2**16 time, 2 pol, 1024 freq, at 800MHz / (2*1024) samplerate
Read with baseband VDIF package, need byte to sample conversions for folding
"""
fh = vdif.open(raw_files[0], 'rs', sample_rate=samplerate)
self.time0 = fh.tell(unit='time')
self.npol = fh.nthread
nchan = fh.nchan
self.samplerate = samplerate
self.fedge_at_top = fedge_at_top
if fedge.isscalar:
self.fedge = fedge
f = fftshift(fftfreq(nchan,
(2. / samplerate).to(u.s).value)) * u.Hz
if fedge_at_top:
self.frequencies = fedge - (f - f[0])
else:
self.frequencies = fedge + (f - f[0])
else:
assert fedge.shape == (nchan, )
self.frequencies = fedge
if fedge_at_top:
self.fedge = self.frequencies.max()
else:
self.fedge = self.frequencies.min()
self.dtsample = (nchan * 2 / samplerate).to(u.s)
if comm is None or comm.rank == 0:
print("In AROCHIMEVdifData, calling super")
print("Start time: ", self.time0.iso)
super(AROCHIMEVdifData, self).__init__(raw_files,
blocksize,
dtype,
nchan,
comm=comm)
if self.filesize % self.fh_raw.header0.framesize != 0:
raise ValueError("File size is not an integer number of packets")
self.filesize = (self.filesize // self.fh_raw.header0.framesize *
self.fh_raw.header0.payloadsize)
def test_frequency_sideband_polarization_propagation2(self):
fh = vdif.open(SAMPLE_VDIF)
# Add different frequency, sideband, and polarization information.
# (Note: these are incorrect; just for testing purposes.)
fh.frequency = 311.25 * u.MHz + (np.arange(8.) // 4) * 16. * u.MHz
fh.sideband = np.tile([-1, 1], 4)
fh.polarization = np.tile(['L', 'L', 'R', 'R'], 2)
with self.get_reshape_and_transpose(fh, (2, 2, 2), (-1, -3, -2)) as tt:
assert tt.frequency.shape == (2, 1)
assert np.all(tt.frequency == fh.frequency[::4].reshape(2, 1))
assert tt.sideband.shape == (2, 1, 1)
assert np.all(tt.sideband == fh.sideband[:2].reshape(2, 1, 1))
assert tt.polarization.shape == (2, )
assert np.all(tt.polarization == fh.polarization[:4:2])
def open(self, number=0):
"""Open a new file in the sequence.
Parameters
----------
file_number : int
The number of the file to open. Default is 0, i.e., the first one.
"""
if number != self.current_file_number:
self.close()
self.fh_raw = vdif.open(self.files[number], 'rs', sample_rate=(1/self.dtsample).to(u.Hz))
self.current_file_number = number
return self.fh_raw
def test_channelize_frequency_real(self):
"""Test frequency calculation."""
fh = vdif.open(SAMPLE_VDIF)
# Add frequency information by hand for now.
fh.frequency = 311.25 * u.MHz + (np.arange(8.) // 2) * 16. * u.MHz
# Note: sideband is actually incorrect for this VDIF file;
# this is for testing only.
fh.sideband = np.tile([-1, +1], 4)
ct = Channelize(fh, self.n)
assert np.all(ct.sideband == self.ref_sideband)
assert np.all(ct.frequency == self.ref_frequency)
ct.close()
def open(self, number=0):
"""Open a new file in the sequence.
Parameters
----------
file_number : int
The number of the file to open. Default is 0, i.e., the first one.
"""
if number != self.current_file_number:
self.close()
self.fh_raw = vdif.open(self.files[number],
'rs',
sample_rate=(1 / self.dtsample).to(u.Hz))
self.current_file_number = number
return self.fh_raw
def test_basetaskbase(self):
fh = vdif.open(SAMPLE_VDIF)
mh = Multiply(fh, 2.)
# Check sample pointer.
assert mh.sample_rate == fh.sample_rate
assert mh.shape == fh.shape
assert mh.size == np.prod(mh.shape)
assert mh.ndim == fh.ndim
assert mh.tell() == 0
assert mh.tell(unit='time') == mh.time == mh.start_time
assert mh.stop_time == fh.stop_time
expected = fh.read() * 2.
data = mh.read()
assert np.all(data == expected)
assert mh.time == fh.stop_time
def setup(self):
"""Pre-calculate channelized data."""
self.n = 1024
with vdif.open(SAMPLE_VDIF) as fh:
self.ref_start_time = fh.start_time
self.ref_sample_rate = fh.sample_rate
data = fh.read()
self.raw_data = data
last_sample = self.n * (data.shape[0] // self.n)
part = data[:last_sample].reshape((-1, self.n) + data.shape[1:])
FFT = get_fft_maker()
rfft = FFT(shape=part.shape, dtype=part.dtype, axis=1,
sample_rate=self.ref_sample_rate)
self.ref_data = rfft(part)
self.ref_sideband = np.tile([-1, 1], 4)
self.ref_frequency = ((311.25 + 16 * (np.arange(8) // 2)) * u.MHz +
self.ref_sideband * rfft.frequency)
def test_taskbase_exceptions(self):
"""Test exceptions in TaskBase."""
with vdif.open(SAMPLE_VDIF) as fh:
rt = ReshapeTime(fh, 1024, samples_per_frame=3)
# Check that reading beyond the bounds of the data leads to an
# error.
rt.seek(0, 2)
with pytest.raises(EOFError):
rt.read(1)
rt.seek(-2, 'end')
with pytest.raises(EOFError):
rt.read(10)
rt.seek(-2, 'end')
with pytest.raises(EOFError):
rt.read(out=np.empty((5,) + rt.sample_shape))
rt.seek(-4, 'start')
with pytest.raises(OSError):
rt.read(1)
# Check invalid whence.
with pytest.raises(ValueError):
rt.seek(1, 'now')
with pytest.raises(ValueError):
rt.seek(1, 3)
# Check external array shape mismatch raises an error.
with pytest.raises(AssertionError):
rt.read(out=np.empty(3))
# Check missing frequency/sideband definitions
with pytest.raises(AttributeError):
rt.frequency
with pytest.raises(AttributeError):
rt.sideband
with pytest.raises(ValueError):
ReshapeTime(fh, 1024, samples_per_frame=3,
frequency=np.arange(4.)*u.GHz)
with pytest.raises(ValueError):
ReshapeTime(fh, 1024, samples_per_frame=3,
sideband=np.ones((2, 8), dtype=int))
def __init__(self,
source_strm,
dm,
reference_frequency=None,
samples_per_frame=None,
frequencies=None,
sideband=None,
fft=None):
if isinstance(source_strm, list):
self.fh = vdif.open(source_strm)
else:
self.fh = source_strm
self.dedispersed = Dedisperse(self.fh,
dm,
reference_frequency=reference_frequency,
samples_per_frame=samples_per_frame,
frequency=frequencies,
sideband=sideband)
self.squared = Square(self.dedispersed)
self.outstream = self.squared
def __init__(self, raw_files, blocksize, samplerate, fedge, fedge_at_top,
time_offset=0.0*u.s, dtype='cu4bit,cu4bit', comm=None):
"""ARO data acquired with a CHIME correlator, saved in VDIF format.
Files are 2**16 time, 2 pol, 1024 freq, at 800MHz / (2*1024) samplerate
Read with baseband VDIF package, need byte to sample conversions for folding
"""
fh = vdif.open(raw_files[0], 'rs', sample_rate=samplerate)
self.time0 = fh.tell(unit='time')
self.npol = fh.nthread
nchan = fh.nchan
self.samplerate = samplerate
self.fedge_at_top = fedge_at_top
if fedge.isscalar:
self.fedge = fedge
f = fftshift(fftfreq(nchan, (2./samplerate).to(u.s).value)) * u.Hz
if fedge_at_top:
self.frequencies = fedge - (f-f[0])
else:
self.frequencies = fedge + (f-f[0])
else:
assert fedge.shape == (nchan,)
self.frequencies = fedge
if fedge_at_top:
self.fedge = self.frequencies.max()
else:
self.fedge = self.frequencies.min()
self.dtsample = (nchan * 2 / samplerate).to(u.s)
if comm is None or comm.rank == 0:
print("In AROCHIMEVdifData, calling super")
print("Start time: ", self.time0.iso)
super(AROCHIMEVdifData, self).__init__(raw_files, blocksize, dtype, nchan,
comm=comm)
if self.filesize % self.fh_raw.header0.framesize != 0:
raise ValueError("File size is not an integer number of packets")
self.filesize = (self.filesize // self.fh_raw.header0.framesize *
self.fh_raw.header0.payloadsize)
def open(self):
self.fh = vdif.open(self.flist[self.findex], 'rs', sample_rate=self.sample_rate)
path = sys.argv[3]
filelist = glob.glob('%s*vdif' % (path))
filelist = np.sort(filelist)
N = int(T//tfile)+1
Npcore = int(T // (tfile*Csize)) + 1
for i in range(rank*Npcore + dstart, (rank+1)*Npcore + dstart):
if (i - dstart) > N:
print("Rank %s exiting" % (rank))
break
print("Rank %s on %s of %s" % ( rank, (i - rank*Npcore - dstart), Npcore) )
fn = filelist[i]
fh = vdif.open(fn, mode='rs', sample_rate=sample_rate)
print("reading")
d = fh.read(size)
# Turn into chunked dask array
print("de-dispersing")
d = da.from_array(d, chunks=(d.shape[0],d.shape[1], 32))
d = da.fft.fft(d, axis=0)
d *= dd_coh[:,np.newaxis]
d = da.fft.ifft(d, axis=0)
# De-Chunk the array, to allow efficient rechaping
print("reshaping and forming waterfall")
d = d.rechunk(d.shape)
d = abs(d).reshape(-1, binf, 2, 1024).mean(1)
w[(i-dstart)*ntbin:(i-dstart+1)*ntbin] = d
