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cleans up rawimage _get_length() and __get_item__() functions #610

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Jan 25, 2024
Merged

cleans up rawimage _get_length() and __get_item__() functions #610

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63 changes: 25 additions & 38 deletions hexrd/imageseries/load/rawimage.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
""" Adapter class for raw image reader
"""
import warnings
""" Adapter class for raw image reader"""
import os

import numpy as np
import yaml
Expand All @@ -17,8 +16,10 @@ class RawImageSeriesAdapter(ImageSeriesAdapter):
def __init__(self, fname, **kwargs):
"""Image data in custom format

*fname* - filename of the data file
*kwargs* - keyword arguments (none required)
Parameters
----------
fname: string or Path
name of input YAML file describing the format
"""
self.fname = fname
with open(fname, "r") as f:
Expand All @@ -27,14 +28,15 @@ def __init__(self, fname, **kwargs):
self.fname = y['filename']
self.dtype = self._get_dtype(y['scalar'])
self._shape = tuple((int(si) for si in y['shape'].split()))
self.framesize = self._shape[0]*self._shape[1]
self._frame_size = self._shape[0] * self._shape[1]
self._frame_bytes = self._frame_size * self.dtype.itemsize
self.skipbytes = y['skip']
self._len = self._get_length()
self._meta = dict()
self.kwargs = kwargs

# Prepare to read
self.iframe = -1
# Open file for reading.
self.f = open(self.fname, "r")

def _get_dtype(self, scalar):
numtype = scalar['type']
Expand All @@ -51,19 +53,18 @@ def _get_dtype(self, scalar):

def _get_length(self):
"""Read file and determine length"""
iframe = 0
with open(self.fname, "r") as f:
_ = np.fromfile(f, np.byte, count=self.skipbytes)
# now keep reading frames until EOF
moreframes = True
while moreframes:
_ = np.fromfile(f, self.dtype, count=self.framesize)
if len(_) == self.framesize:
iframe += 1
else:
moreframes = False

return iframe
nbytes = os.path.getsize(self.fname)
if nbytes % self._frame_bytes == self.skipbytes:
nframes = (nbytes - self.skipbytes) // self._frame_bytes
else:
msg = (
f"Total number of bytes ({nbytes}) does not work with "
f"skipbytes ({self.skipbytes}) and "
f"_frame_size ({self._frame_size}). Check the skipbytes value."
)
raise ValueError(msg)

return nframes

@staticmethod
def typechars(numtype, bytes_=4, signed=False, little=True):
Expand Down Expand Up @@ -103,23 +104,9 @@ def __iter__(self):
return ImageSeriesIterator(self)

def __getitem__(self, key):
if self.iframe < 0:
self.f = open(self.fname, "r")
_ = np.fromfile(self.f, np.byte, count=self.skipbytes)
self.iframe = 0
if key == 0:
self.f.seek(0, 0)
_ = np.fromfile(self.f, np.byte, count=self.skipbytes) #dcp fix to make sure bytes are properly skipped
self.iframe = 0
if key != self.iframe:
msg = "frame %d not available, series must be read in sequence!"
raise ValueError(msg % key)
frame = np.fromfile(self.f, self.dtype, count=self.framesize)
self.iframe += 1
if self.iframe == len(self):
self.iframe = -1
self.f.close()

count = key * self._frame_bytes + self.skipbytes
self.f.seek(count, 0)
frame = np.fromfile(self.f, self.dtype, count=self._frame_size)
return frame.reshape(self.shape)

@property
Expand Down
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