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Add support for large integer bit flags #56

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merged 2 commits into from
Jan 29, 2018
Merged

Add support for large integer bit flags #56

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Add support for large integer bit flags
mcara Jan 29, 2018
57952ed
Add support for large integer bit flags
mcara Jan 29, 2018
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29 changes: 22 additions & 7 deletions lib/stsci/tools/bitmask.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,14 +8,14 @@

"""

import numpy as np
import sys
import warnings
import six
import numpy as np
from astropy.utils import deprecated


__version__ = '1.0.0'
__vdate__ = '16-March-2017'
__version__ = '1.1.0'
__vdate__ = '29-January-2018'
__author__ = 'Mihai Cara'


Expand All @@ -41,7 +41,17 @@
# and string comma- (or '+') separated lists of bit flags).
# 5. Added 'is_bit_flag()' function to check if an integer number has
# only one bit set (i.e., that it is a power of 2).

# 1.1.0 (29-January-2018) - Multiple enhancements:
# 1. Added support for long type in Python 2.7 in
# `interpret_bit_flags()` and `bitfield_to_boolean_mask()`.
# 2. `interpret_bit_flags()` now always returns `int` (or `int` or `long`
# in Python 2.7). Previously when input was of integer-like type
# (i.e., `numpy.uint64`), it was not converted to Python `int`.
# 3. `bitfield_to_boolean_mask()` will no longer crash when
# `ignore_flags` argument contains bit flags beyond what the type of
# the argument `bitfield` can hold.
#
INT_TYPE = (int, long,) if sys.version_info < (3,) else (int,)

def is_bit_flag(n):
"""
Expand All @@ -68,7 +78,7 @@ def is_bit_flag(n):

def _is_int(n):
return (
(isinstance(n, int) and not isinstance(n, bool)) or
(isinstance(n, INT_TYPE) and not isinstance(n, bool)) or
(isinstance(n, np.generic) and np.issubdtype(n, np.integer))
)

Expand Down Expand Up @@ -136,7 +146,7 @@ def interpret_bit_flags(bit_flags, flip_bits=None):
allow_non_flags = False

if _is_int(bit_flags):
return (~int(bit_flags) if flip_bits else bit_flags)
return (~int(bit_flags) if flip_bits else int(bit_flags))

elif bit_flags is None:
if has_flip_bits:
Expand Down Expand Up @@ -409,6 +419,11 @@ def bitfield_to_boolean_mask(bitfield, ignore_flags=0, flip_bits=None,
mask = np.zeros_like(bitfield, dtype=dtype)
return mask

# filter out bits beyond the maximum supported by the data type:
supported_flags = int(np.bitwise_not(bitfield.dtype.type(0)))
ignore_mask = ignore_mask & supported_flags

# invert the "ignore" mask:
ignore_mask = np.bitwise_not(bitfield.dtype.type(ignore_mask))

mask = np.empty_like(bitfield, dtype=np.bool_)
Expand Down