def strip(a, mode='right'):
"""strip(bitarray, mode='right', /) -> bitarray
Strip zeros from left, right or both ends.
Allowed values for mode are the strings: `left`, `right`, `both`
"""
if not isinstance(a, bitarray):
raise TypeError("bitarray expected, got '%s'" % type(a).__name__)
if not isinstance(mode, str):
raise TypeError("str expected for mode")
if mode not in ('left', 'right', 'both'):
raise ValueError("allowed values 'left', 'right', 'both', got: %r" %
mode)
first = 0
if mode in ('left', 'both'):
try:
first = a.index(1)
except ValueError:
return bitarray(0, a.endian())
last = len(a) - 1
if mode in ('right', 'both'):
try:
last = rindex(a)
except ValueError:
return bitarray(0, a.endian())
return a[first:last + 1]
def strip(a, mode='right'):
"""strip(bitarray, mode='right', /) -> bitarray
Return a new bitarray with zeros stripped from left, right or both ends.
Allowed values for mode are the strings: `left`, `right`, `both`
"""
if not isinstance(a, bitarray):
raise TypeError("bitarray expected, got '%s'" % type(a).__name__)
if not isinstance(mode, str):
raise TypeError("str expected for mode, got '%s'" % type(a).__name__)
if mode not in ('left', 'right', 'both'):
raise ValueError("mode must be 'left', 'right' or 'both', got: %r" %
mode)
first = 0
if mode in ('left', 'both'):
try:
first = a.index(1)
except ValueError:
return a[:0]
last = len(a) - 1
if mode in ('right', 'both'):
try:
last = rindex(a)
except ValueError:
return a[:0]
return a[first:last + 1]
def int2ba(i, length=None, endian='big'):
"""int2ba(int, /, length=None, endian='big') -> bitarray
Convert the given integer into a bitarray (with given endianness,
and no leading (big-endian) / trailing (little-endian) zeros).
If length is provided, the result will be of this length, and an
`OverflowError` will be raised, if the integer cannot be represented
within length bits.
"""
if not isinstance(i, (int, long) if _is_py2 else int):
raise TypeError("integer expected")
if i < 0:
raise ValueError("non-negative integer expected")
if length is not None:
if not isinstance(length, int):
raise TypeError("integer expected for length")
if length <= 0:
raise ValueError("integer larger than 0 expected for length")
if not isinstance(endian, str):
raise TypeError("string expected for endian")
if endian not in ('big', 'little'):
raise ValueError("endian can only be 'big' or 'little'")
if i == 0:
# there a special cases for 0 which we'd rather not deal with below
return zeros(length or 1, endian=endian)
big_endian = bool(endian == 'big')
if _is_py2:
c = bytearray()
while i:
i, r = divmod(i, 256)
c.append(r)
if big_endian:
c.reverse()
b = bytes(c)
else: # py3
b = i.to_bytes(bits2bytes(i.bit_length()), byteorder=endian)
a = bitarray(endian=endian)
a.frombytes(b)
la = a.length()
if la == length:
return a
if length is None:
return strip(a, 'left' if big_endian else 'right')
if la > length:
size = (la - a.index(1)) if big_endian else (rindex(a) + 1)
if size > length:
raise OverflowError("cannot represent %d bit integer in "
"%d bits" % (size, length))
a = a[la - length:] if big_endian else a[:length - la]
if la < length:
if big_endian:
a = zeros(length - la, 'big') + a
else:
a += zeros(length - la, 'little')
assert a.length() == length
return a
