#!/usr/bin/env python
__version__ = '2.0'
__author__ = "Avinash Kak (kak@purdue.edu)"
__date__ = '2010-April-25'
__url__ = 'http://RVL4.ecn.purdue.edu/~kak/dist/BitVector-2.0.html'
__copyright__ = "(C) 2010 Avinash Kak. Python Software Foundation."
import array
import operator
_hexdict = { '0' : '0000', '1' : '0001', '2' : '0010', '3' : '0011',
'4' : '0100', '5' : '0101', '6' : '0110', '7' : '0111',
'8' : '1000', '9' : '1001', 'a' : '1010', 'b' : '1011',
'c' : '1100', 'd' : '1101', 'e' : '1110', 'f' : '1111' }
def _readblock( blocksize, bitvector ): #(R1)
'''
If this function can read all blocksize bits, it peeks
ahead to see if there is anything more to be read in the
file. It uses tell-read-seek mechanism for this in lines
(R18) through (R21). If there is nothing further to be
read, it sets the more_to_read attribute of the
bitvector object to False. Obviously, this can only be
done for seekable streams such as those connected with
disk files. According to Blair Houghton, a similar
feature could presumably be implemented for socket
streams by using recv() or recvfrom() if you set the
flags argument to MSG_PEEK.
'''
global hexdict #(R2)
bitstring = '' #(R3)
i = 0 #(R4)
while ( i < blocksize / 8 ): #(R5)
i += 1 #(R6)
byte = bitvector.FILEIN.read(1) #(R7)
if byte == '': #(R8)
if len(bitstring) < blocksize: #(R9)
bitvector.more_to_read = False #(R10)
return bitstring #(R11)
hexvalue = hex( ord( byte ) ) #(R12)
hexvalue = hexvalue[2:] #(R13)
if len( hexvalue ) == 1: #(R14)
hexvalue = '0' + hexvalue #(R15)
bitstring += _hexdict[ hexvalue[0] ] #(R16)
bitstring += _hexdict[ hexvalue[1] ] #(R17)
file_pos = bitvector.FILEIN.tell() #(R18)
# peek at the next byte; moves file position only if a
# byte is read
next_byte = bitvector.FILEIN.read(1) #(R19)
if next_byte: #(R20)
# pretend we never read the byte
bitvector.FILEIN.seek( file_pos ) #(R21)
else: #(R22)
bitvector.more_to_read = False #(R23)
return bitstring #(R24)
#-------------------- BitVector Class Definition ----------------------
class BitVector( object ): #(A1)
def __init__( self, *args, **kwargs ): #(A2)
if args: #(A3)
raise ValueError( #(A4)
'''BitVector constructor can only be
called with keyword arguments for
the following keywords: filename,
fp (for fileobject), size,
intValue, bitlist (for a list or
tuple of bits, or bitstring)''')
filename = fp = intVal = size = bitlist = bitstring = None #(A5)
if kwargs.has_key('filename'):filename=kwargs.pop('filename')#(A6)
if kwargs.has_key('fp'): fp = kwargs.pop('fp') #(A7)
if kwargs.has_key('size'): size = kwargs.pop('size') #(A8)
if kwargs.has_key('intVal'): intVal = kwargs.pop('intVal') #(A9)
if kwargs.has_key('bitlist'):
bitlist = kwargs.pop('bitlist') #(A10)
if kwargs.has_key('bitstring') :
bitstring = kwargs.pop('bitstring') #(A11)
self.filename = None #(A12)
self.size = 0 #(A13)
self.FILEIN = None #(A14)
self.FILEOUT = None #(A15)
if filename: #(A16)
if fp or size or intVal or bitlist or bitstring: #(A17)
raise ValueError( #(A18)
'''When filename is specified, you cannot
give values to any other constructor args''')
self.filename = filename #(A19)
self.FILEIN = open( filename, 'rb' ) #(A20)
self.more_to_read = True #(A21)
return #(A22)
elif fp: #(A23)
if filename or size or intVal or bitlist or bitstring: #(A24)
raise ValueError( #(A25)
'''When fileobject is specified, you cannot
give values to any other constructor args''')
bits = self.read_bits_from_fileobject( fp ) #(A26)
bitlist = map( int, bits ) #(A27)
self.size = len( bitlist ) #(A28)
elif intVal or intVal == 0: #(A29)
if filename or fp or bitlist or bitstring: #(A30)
raise ValueError( #(A31)
'''When intVal is specified, you can only give
a value to the 'size' constructor arg''')
if intVal == 0: #(A32)
bitlist = [0] #(A33)
if not size: #(A34)
self.size = 1 #(A35)
else: #(A36)
if size < len(bitlist): #(A37)
raise ValueError( #(A38)
'''The value specified for size must be
at least as large as for the smallest
bit vector possible for intVal''')
n = size - len(bitlist) #(A39)
bitlist = [0]*n + bitlist #(A40)
self.size = len( bitlist ) #(A41)
else: #(A42)
hexVal = hex( intVal ).lower().rstrip('l') #(A43)
hexVal = hexVal[2:] #(A44)
if len( hexVal ) == 1: #(A45)
hexVal = '0' + hexVal #(A46)
bitlist = ''.join(map(lambda x: _hexdict[x],hexVal))#(A47)
bitlist = map( int, bitlist ) #(A48)
i = 0 #(A49)
while ( i < len( bitlist ) ): #(A50)
if bitlist[i] == 1: break #(A51)
i += 1 #(A52)
del bitlist[0:i] #(A53)
if not size: #(A54)
self.size = len( bitlist ) #(A55)
else: #(A56)
if size < len(bitlist): #(A57)
raise ValueError( #(A58)
'''The value specified for size must be
at least as large as for the smallest
bit vector possible for intVal''')
n = size - len(bitlist) #(A59)
bitlist = [0]*n + bitlist #(A60)
self.size = len( bitlist ) #(A61)
elif size >= 0: #(A62)
if filename or fp or intVal or bitlist or bitstring: #(A63)
raise ValueError( #(A64)
'''When size is specified (without an intVal),
you cannot give values to any other
constructor args''')
self.size = size #(A65)
two_byte_ints_needed = (size + 15) // 16 #(A66)
self.vector = array.array('H', [0]*two_byte_ints_needed)#(A67)
return #(A68)
elif bitstring or bitstring == '': #(A69)
if filename or fp or size or intVal or bitlist: #(A70)
raise ValueError( #(A71)
'''When a bitstring is specified, you cannot
give values to any other constructor args''')
bitlist = map( int, list(bitstring) ) #(A72)
self.size = len( bitlist ) #(A73)
elif bitlist: #(A74)
if filename or fp or size or intVal or bitstring: #(A75)
raise ValueError( #(A76)
'''When bits are specified, you cannot
give values to any other constructor args''')
self.size = len( bitlist ) #(A77)
else: #(A78)
raise ValueError("wrong arg(s) for constructor") #(A79)
two_byte_ints_needed = (len(bitlist) + 15) // 16 #(A80)
self.vector = array.array( 'H', [0]*two_byte_ints_needed ) #(A81)
map( self._setbit, enumerate(bitlist), bitlist) #(A82)
def _setbit( self, posn, val ): #(B1)
'Set the bit at the designated position to the value shown'
if val not in (0, 1): #(B2)
raise ValueError( "incorrect value for a bit" ) #(B3)
if isinstance( posn, (tuple) ): #(B4)
posn = posn[0] #(B5)
if posn >= self.size or posn < -self.size: #(B6)
raise ValueError( "index range error" ) #(B7)
if posn < 0: posn = self.size + posn #(B8)
block_index = posn // 16 #(B9)
shift = posn & 15 #(B10)
cv = self.vector[block_index] #(B11)
if ( cv >> shift ) & 1 != val: #(B12)
self.vector[block_index] = cv ^ (1 << shift) #(B13)
def _getbit( self, posn ): #(C1)
'Get the bit from the designated position'
if posn >= self.size or posn < -self.size: #(C2)
raise ValueError( "index range error" ) #(C3)
if posn < 0: posn = self.size + posn #(C4)
return ( self.vector[posn//16] >> (posn&15) ) & 1 #(C5)
def __xor__(self, other): #(E1)
'''
Take a bitwise 'xor' of the bit vector on which
the method is invoked with the argument bit vector.
Return the result as a new bit vector. If the two
bit vectors are not of the same size, pad the shorter
one with zeros from the left.
'''
if self.size < other.size: #(E2)
bv1 = self._resize_pad_from_left(other.size - self.size) #(E3)
bv2 = other #(E4)
elif self.size > other.size: #(E5)
bv1 = self #(E6)
bv2 = other._resize_pad_from_left(self.size - other.size)#(E7)
else: #(E8)
bv1 = self #(E9)
bv2 = other #(E10)
res = BitVector( size = bv1.size ) #(E11)
lpb = map(operator.__xor__, bv1.vector, bv2.vector) #(E12)
res.vector = array.array( 'H', lpb ) #(E13)
return res #(E14)
def __and__(self, other): #(F1)
'''
Take a bitwise 'and' of the bit vector on which the method is
invoked with the argument bit vector. Return the result as a
new bit vector. If the two bit vectors are not of the same
size, pad the shorter one with zeros from the left.
'''
if self.size < other.size: #(F2)
bv1 = self._resize_pad_from_left(other.size - self.size) #(F3)
bv2 = other #(F4)
elif self.size > other.size: #(F5)
bv1 = self #(F6)
bv2 = other._resize_pad_from_left(self.size - other.size)#(F7)
else: #(F8)
bv1 = self #(F9)
bv2 = other #(F10)
res = BitVector( size = bv1.size ) #(F11)
lpb = map(operator.__and__, bv1.vector, bv2.vector) #(F12)
res.vector = array.array( 'H', lpb ) #(F13)
return res #(F14)
def __or__(self, other): #(G1)
'''
Take a bitwise 'or' of the bit vector on which the
method is invoked with the argument bit vector. Return
the result as a new bit vector. If the two bit vectors
are not of the same size, pad the shorter one with
zero's from the left.
'''
if self.size < other.size: #(G2)
bv1 = self._resize_pad_from_left(other.size - self.size) #(G3)
bv2 = other #(G4)
elif self.size > other.size: #(G5)
bv1 = self #(G6)
bv2 = other._resize_pad_from_left(self.size - other.size)#(G7)
else: #(G8)
bv1 = self #(G9)
bv2 = other #(G10)
res = BitVector( size = bv1.size ) #(G11)
lpb = map(operator.__or__, bv1.vector, bv2.vector) #(G12)
res.vector = array.array( 'H', lpb ) #(G13)
return res #(G14)
def __invert__(self): #(H1)
'''
Invert the bits in the bit vector on which the
method is invoked and return the result as a new
bit vector.
'''
res = BitVector( size = self.size ) #(H2)
lpb = map( operator.__inv__, self.vector ) #(H3)
res.vector = array.array( 'H' ) #(H3)
for i in range(len(lpb)): #(H4)
res.vector.append( lpb[i] & 0x0000FFFF ) #(H5)
return res #(H6)
def __add__(self, other): #(J1)
'''
Concatenate the argument bit vector with the bit
vector on which the method is invoked. Return the
concatenated bit vector as a new BitVector object.
'''
i = 0 #(J2)
outlist = [] #(J3)
while ( i < self.size ): #(J4)
outlist.append( self[i] ) #(J5)
i += 1 #(J6)
i = 0 #(J7)
while ( i < other.size ): #(J8)
outlist.append( other[i] ) #(J9)
i += 1 #(J10)
return BitVector( bitlist = outlist ) #(J11)
def _getsize(self): #(K1)
'Return the number of bits in a bit vector.'
return self.size #(K2)
def read_bits_from_file(self, blocksize): #(L1)
'''
Read blocksize bits from a disk file and return a
BitVector object containing the bits. If the file
contains fewer bits than blocksize, construct the
BitVector object from however many bits there are
in the file. If the file contains zero bits, return
a BitVector object of size attribute set to 0.
'''
error_str = '''You need to first construct a BitVector
object with a filename as argument''' #(L2)
if not self.filename: #(L3)
raise SyntaxError( error_str ) #(L4)
if blocksize % 8 != 0: #(L5)
raise ValueError( "block size must be a multiple of 8" ) #(L6)
bitstr = _readblock( blocksize, self ) #(L7)
if len( bitstr ) == 0: #(L8)
return BitVector( size = 0 ) #(L9)
else: #(L10)
return BitVector( bitstring = bitstr ) #(L11)
def read_bits_from_fileobject( self, fp ): #(M1)
'''
This function is meant to read a bit string from a
file like object.
'''
bitlist = [] #(M2)
while 1: #(M3)
bit = fp.read() #(M4)
if bit == '': return bitlist #(M5)
bitlist += bit #(M6)
def write_bits_to_fileobject( self, fp ): #(N1)
'''
This function is meant to write a bit vector directly to
a file like object. Note that whereas 'write_to_file'
method creates a memory footprint that corresponds exactly
to the bit vector, the 'write_bits_to_fileobject' actually
writes out the 1's and 0's as individual items to the
file object. That makes this method convenient for
creating a string representation of a bit vector,
especially if you use the StringIO class, as shown in
the test code.
'''
for bit_index in range(self.size): #(N2)
if self[bit_index] == 0: #(N3)
fp.write( '0' ) #(N4)
else: #(N5)
fp.write( '1' ) #(N6)
def divide_into_two(self): #(P1)
'''
Divides an even-sized bit vector into two and returns
the two halves as a list of two bit vectors.
'''
if self.size % 2 != 0: #(P2)
raise ValueError( "must have even num bits" ) #(P3)
i = 0 #(P4)
outlist1 = [] #(P5)
while ( i < self.size /2 ): #(P6)
outlist1.append( self[i] ) #(P7)
i += 1 #(P8)
outlist2 = [] #(P9)
while ( i < self.size ): #(P10)
outlist2.append( self[i] ) #(P11)
i += 1 #(P12)
return [ BitVector( bitlist = outlist1 ),
BitVector( bitlist = outlist2 ) ] #(P13)
def permute(self, permute_list): #(Q1)
'''
Permute a bit vector according to the indices
shown in the second argument list. Return the
permuted bit vector as a new bit vector.
'''
if max(permute_list) > self.size -1: #(Q2)
raise ValueError( "Bad permutation index" ) #(Q3)
outlist = [] #(Q4)
i = 0 #(Q5)
while ( i < len( permute_list ) ): #(Q6)
outlist.append( self[ permute_list[i] ] ) #(Q7)
i += 1 #(Q8)
return BitVector( bitlist = outlist ) #(Q9)
def unpermute(self, permute_list): #(S1)
'''
Unpermute the bit vector according to the
permutation list supplied as the second argument.
If you first permute a bit vector by using permute()
and then unpermute() it using the same permutation
list, you will get back the original bit vector.
'''
if max(permute_list) > self.size -1: #(S2)
raise ValueError( "Bad permutation index" ) #(S3)
if self.size != len( permute_list ): #(S4)
raise ValueError( "Bad size for permute list" ) #(S5)
out_bv = BitVector( size = self.size ) #(S6)
i = 0 #(S7)
while ( i < len(permute_list) ): #(S8)
out_bv[ permute_list[i] ] = self[i] #(S9)
i += 1 #(S10)
return out_bv #(S11)
def write_to_file(self, file_out): #(T1)
'''
(Contributed by Joe Davidson) Write the bitvector
to the file object file_out. (A file object is
returned by a call to open()). Since all file I/O
is byte oriented, the bitvector must be multiple
of 8 bits. Each byte treated as MSB first (0th index).
'''
err_str = '''Only a bit vector whose length is a multiple of 8
can be written to a file. Use the padding functions
to satisfy this constraint.''' #(T2)
if not self.FILEOUT:
self.FILEOUT = file_out
if self.size % 8: #(T3)
raise ValueError( err_str ) #(T4)
for byte in range(self.size/8 ): #(T5)
value = 0 #(T6)
for bit in range(8): #(T7)
value += (self._getbit( byte*8 + (7 - bit) ) << bit )#(T8)
file_out.write( chr(value) ) #(T9)
def close_file_object(self): #(U1)
'''
For closing a file object that was used for reading
the bits into one or more BitVector objects.
'''
if not self.FILEIN: #(U2)
raise SyntaxError( "No associated open file" ) #(U3)
self.FILEIN.close() #(U4)
def intValue(self): #(V1)
'Return the integer value of a bitvector'
intVal = 0 #(V2)
for i in range(self.size): #(V3)
intVal += self[i] * (2 ** (self.size - i - 1)) #(V4)
return intVal #(V5)
def __lshift__( self, n ): #(W1)
'For an in-place left circular shift by n bit positions'
for i in range(n): #(W2)
self.circular_rotate_left_by_one() #(W3)
def __rshift__( self, n ): #(W4)
'For an in-place right circular shift by n bit positions.'
for i in range(n): #(W5)
self.circular_rotate_right_by_one() #(W6)
def circular_rotate_left_by_one(self): #(X1)
'For a one-bit in-place left circular shift'
size = len(self.vector) #(X2)
bitstring_leftmost_bit = self.vector[0] & 1 #(X3)
left_most_bits = map(operator.__and__, self.vector, [1]*size)#(X4)
left_most_bits.append(left_most_bits[0]) #(X5)
del(left_most_bits[0]) #(X6)
self.vector = map(operator.__rshift__, self.vector, [1]*size)#(X7)
self.vector = map( operator.__or__, self.vector, \
map(operator.__lshift__, left_most_bits, [15]*size) ) #(X8)
self._setbit(self.size -1, bitstring_leftmost_bit) #(X9)
def circular_rotate_right_by_one(self): #(Y1)
'For a one-bit in-place right circular shift'
size = len(self.vector) #(Y2)
bitstring_rightmost_bit = self[self.size - 1] #(Y3)
right_most_bits = map( operator.__and__,
self.vector, [0x8000]*size ) #(Y4)
self.vector = \
map( operator.__and__, self.vector, [~0x8000]*size ) #(Y5)
right_most_bits.insert(0, bitstring_rightmost_bit) #(Y6)
right_most_bits.pop() #(Y7)
self.vector = map(operator.__lshift__, self.vector, [1]*size)#(Y8)
self.vector = map( operator.__or__, self.vector, \
map(operator.__rshift__, right_most_bits, [15]*size) ) #(Y9)
self._setbit(0, bitstring_rightmost_bit) #(Y10)
def circular_rot_left(self): #(Z1)
'''
This is merely another implementation of the method
circular_rotate_left_by_one() shown above. This one
does NOT use map functions. This method carries out a
one-bit left circular shift of a bit vector.
'''
max_index = (self.size -1) // 16 #(Z2)
left_most_bit = self.vector[0] & 1 #(Z3)
self.vector[0] = self.vector[0] >> 1 #(Z4)
for i in range(1, max_index + 1): #(Z5)
left_bit = self.vector[i] & 1 #(Z6)
self.vector[i] = self.vector[i] >> 1 #(Z7)
self.vector[i-1] |= left_bit << 15 #(Z8)
self._setbit(self.size -1, left_most_bit) #(Z9)
def circular_rot_right(self): #(a1)
'''
This is merely another implementation of the method
circular_rotate_right_by_one() shown above. This one
does NOT use map functions. This method does a one-bit
right circular shift of a bit vector.
'''
max_index = (self.size -1) // 16 #(a2)
right_most_bit = self[self.size - 1] #(a3)
self.vector[max_index] &= ~0x8000 #(a4)
self.vector[max_index] = self.vector[max_index] << 1 #(a5)
for i in range(max_index-1, -1, -1): #(a6)
right_bit = self.vector[i] & 0x8000 #(a7)
self.vector[i] &= ~0x8000 #(a8)
self.vector[i] = self.vector[i] << 1 #(a9)
self.vector[i+1] |= right_bit >> 15 #(a10)
self._setbit(0, right_most_bit) #(a11)
# Allow array like subscripting for getting and setting:
__getitem__ = _getbit #(b1)
def __setitem__(self, pos, item): #(b2)
'''
This is needed for both slice assignments and for
index assignments. It checks the types of pos and item
to see if the call is for slice assignment. For slice
assignment, pos must be of type 'slice' and item of
type BitVector. For index assignment, the argument types
are checked in the _setbit() method.
'''
# The following section is for slice assignment:
if isinstance( pos, slice ): #(b3)
if (not isinstance( item, BitVector )): #(b4)
raise TypeError('For slice assignment, \
the right hand side must be a BitVector') #(b5)
if ( (pos.stop - pos.start) != len(item) ): #(b6)
raise ValueError('incompatible lengths for \
slice assignment') #(b7)
for i in range( pos.start, pos.stop ): #(b8)
self[i] = item[ i - pos.start ] #(b9)
return #(b10)
# For index assignment use _setbit()
self._setbit( pos, item ) #(b11)
def __getslice__(self, i, j): #(c1)
'Allow slicing with [i:j], [:], etc.'
slicebits = [] #(c2)
if j > self.size: j = self.size #(c3)
for x in range(i,j): #(c4)
slicebits.append( self[x] ) #(c5)
return BitVector( bitlist = slicebits ) #(c6)
# Allow len() to work:
__len__ = _getsize #(d1)
# Allow int() to work:
__int__ = intValue #(d2)
def __iter__( self ): #(d3)
'''
To allow iterations over a bit vector by supporting the
'for bit in bit_vector' syntax:
'''
return BitVectorIterator( self ) #(d4)
def __str__( self ): #(e1)
'To create a print representation'
if self.size == 0: #(e2)
return '' #(e3)
return ''.join( map( str, self ) ) #(e4)
# Compare two bit vectors:
def __eq__(self, other): #(f1)
if self.size != other.size: #(f2)
return False #(f3)
i = 0 #(f4)
while ( i < self.size ): #(f5)
if (self[i] != other[i]): return False #(f6)
i += 1 #(f7)
return True #(f8)
def __ne__(self, other): #(f9)
return not self == other #(f10)
def __lt__(self, other): #(f11)
return self.intValue() < other.intValue() #(f12)
def __le__(self, other): #(f13)
return self.intValue() <= other.intValue() #(f14)
def __gt__(self, other): #(f15)
return self.intValue() > other.intValue() #(f16)
def __ge__(self, other): #(f17)
return self.intValue() >= other.intValue() #(f18)
# Some additional utility functions:
def _make_deep_copy( self ): #(g1)
'Make a deep copy of a bit vector'
copy = str( self ) #(g2)
return BitVector( bitstring = copy ) #(g3)
def _resize_pad_from_left( self, n ): #(g4)
'''
Resize a bit vector by padding with n 0's
from the left. Return the result as a new bit
vector.
'''
new_str = '0'*n + str( self ) #(g5)
return BitVector( bitstring = new_str ) #(g6)
def _resize_pad_from_right( self, n ): #(g7)
'''
Resize a bit vector by padding with n 0's
from the right. Return the result as a new bit
vector.
'''
new_str = str( self ) + '0'*n #(g8)
return BitVector( bitstring = new_str ) #(g9)
def pad_from_left( self, n ): #(g10)
'Pad a bit vector with n zeros from the left'
new_str = '0'*n + str( self ) #(g11)
bitlist = map( int, list(new_str) ) #(g12)
self.size = len( bitlist ) #(g13)
two_byte_ints_needed = (len(bitlist) + 15) // 16 #(g14)
self.vector = array.array( 'H', [0]*two_byte_ints_needed ) #(g15)
map( self._setbit, enumerate(bitlist), bitlist) #(g16)
def pad_from_right( self, n ): #(g17)
'Pad a bit vector with n zeros from the right'
new_str = str( self ) + '0'*n #(g18)
bitlist = map( int, list(new_str) ) #(g19)
self.size = len( bitlist ) #(g20)
two_byte_ints_needed = (len(bitlist) + 15) // 16 #(g21)
self.vector = array.array( 'H', [0]*two_byte_ints_needed ) #(g22)
map( self._setbit, enumerate(bitlist), bitlist) #(g23)
def __contains__( self, otherBitVec ): #(h1)
'''
This supports 'if x in y' and 'if x not in y'
syntax for bit vectors.
'''
if self.size == 0: #(h2)
raise ValueError, "First arg bitvec has no bits" #(h3)
elif self.size < otherBitVec.size: #(h4)
raise ValueError, "First arg bitvec too short" #(h5)
max_index = self.size - otherBitVec.size + 1 #(h6)
for i in range(max_index): #(h7)
if self[i:i+otherBitVec.size] == otherBitVec: #(h8)
return True #(h9)
return False #(h10)
def reset( self, val ): #(j1)
'''
Resets a previously created BitVector to either all
zeros or all ones depending on the argument val.
Returns self to allow for syntax like
bv = bv1[3:6].reset(1)
or
bv = bv1[:].reset(1)
'''
if val not in (0,1): #(j2)
raise ValueError( "Incorrect reset argument" ) #(j3)
bitlist = [val for i in range( self.size )] #(j4)
map( self._setbit, enumerate(bitlist), bitlist ) #(j5)
return self #(j6)
def count_bits( self ): #(k1)
'''
Return the number of bits set in a BitVector instance.
'''
return reduce( lambda x, y: int(x)+int(y), self ) #(k2)
def setValue(self, *args, **kwargs ): #(m1)
'''
Changes the bit pattern associated with a previously
constructed BitVector instance. The allowable modes
for chaning the internally stored bit patten are the
same as for the constructor.
'''
self.__init__( *args, **kwargs ) #(m2)
def count_bits_sparse( self ): #(n1)
'''
For sparse bit vectors, this method, contributed by
Rhiannon, will be much faster. She estimates that
if a bit vector with over 2 millions bits has only
five bits set, this will return the answer in 1/18
of the time taken by the count_bits() method. Note
however, that count_bits() may work much faster for
dense-packed bit vectors. Rhianon's implementation
is based on an algorithm generally known as the
Brian Kernighan's way, although its antecedents
predate its mention by Kernighan and Ritchie.
'''
num = 0 #(n2)
for intval in self.vector: #(n3)
if intval == 0: continue #(n4)
c = 0; iv = intval #(n5)
while iv > 0: #(n6)
iv = iv & (iv -1) #(n7)
c = c + 1 #(n8)
num = num + c #(n9)
return num #(n10)
def jaccard_similarity( self, other ): #(p1)
'''
Computes the Jaccard similarity coefficient
between two bit vectors
'''
assert self.size == other.size, 'vectors of unequal length' #(p2)
intersect = self & other #(p4)
union = self | other #(p5)
return ( intersect.count_bits_sparse()\
/ float( union.count_bits_sparse() ) ) #(p6)
def jaccard_distance( self, other ): #(q1)
'''
Computes the Jaccard distance between two bit vectors
'''
assert self.size == other.size, 'vectors of unequal length' #(q2)
return 1 - self.jaccard_similarity( other ) #(q3)
def hamming_distance( self, other ): #(r1)
'''
Computes the Hamming distance between two bit vectors
'''
assert self.size == other.size, 'vectors of unequal length' #(r2)
diff = self ^ other #(r3)
return diff.count_bits_sparse() #(r4)
def next_set_bit(self, from_index=0): #(s1)
'''
This method, contributed by Jason Allum, calculates
the number of bit positions from the current
position index to the next set bit.
'''
assert from_index >= 0, 'from_index must be nonnegative' #(s2)
i = from_index #(s3)
v = self.vector #(s4)
l = len(v) #(s5)
o = i >> 4 #(s6)
m = 1 << (i & 0x0F) #(s7)
while o < l: #(s8)
h = v[o] #(s9)
if h: #(s10)
while m != (1 << 0x10): #(s11)
if h & m: return i #(s12)
m <<= 1 #(s13)
i += 1 #(s14)
else: #(s15)
i += 0x10 #(s16)
m = 1 #(s17)
o += 1 #(s18)
return -1 #(s19)
def rank_of_bit_set_at_index( self, position ): #(t1)
'''
For a bit that is set at the argument 'position',
this method returns how many bits are set to the
left of that bit. For example, in the bit pattern
000101100100, a call to this method with position
set to 9 will return 4.
'''
assert self[position] == 1, 'the arg bit not set'
bv = self[0:position+1] #(t2)
return bv.count_bits() #(t3)
def isPowerOf2( self ): #(t1)
'''
Determines whether the integer value of a bit vector is
a power of 2.
'''
if self.intValue() == 0: return False #(u2)
bv = self & BitVector( intVal = self.intValue() - 1 ) #(u3)
if bv.intValue() == 0: return True #(u4)
return False #(u5)
def isPowerOf2_sparse( self ): #(v1)
'''
Faster version of isPowerOf2() for sparse bit vectors
'''
if self.count_bits_sparse() == 1: return True #(v2)
return False #(v3)
def reverse( self ): #(w1)
'''
Returns a new bit vector by reversing the bits in the
bit vector on which the method is invoked.
'''
reverseList = [] #(w2)
i = 1 #(w3)
while ( i < self.size + 1 ): #(w4)
reverseList.append( self[ -i ] ) #(w5)
i += 1 #(w6)
return BitVector( bitlist = reverseList ) #(w7)
def gcd( self, other ): #(x1)
'''
Using Euclid's Algorithm, returns the greatest
common divisor of the integer value of the bit
vector on which the method is invoked and the
integer value of the argument bit vector.
'''
a = self.intValue(); b = other.intValue() #(x2)
if a < b: a,b = b,a #(x3)
while b != 0: #(x4)
a, b = b, a % b #(x5)
return BitVector( intVal = a ) #(x6)
def multiplicative_inverse( self, modulus ): #(y1)
'''
Calculates the multiplicative inverse of a bit
vector modulo the bit vector that is supplied as the
argument. Code based on the Extended Euclid's
Algorithm.
'''
MOD = mod = modulus.intValue(); num = self.intValue() #(y2)
x, x_old = 0L, 1L #(y3)
y, y_old = 1L, 0L #(y4)
while mod: #(y5)
quotient = num // mod #(y6)
num, mod = mod, num % mod #(y7)
x, x_old = x_old - x * quotient, x #(y8)
y, y_old = y_old - y * quotient, y #(y9)
if num != 1: #(y10)
return None #(y11)
else: #(y12)
MI = (x_old + MOD) % MOD #(y13)
return BitVector( intVal = MI ) #(y14)
#----------------------- BitVectorIterator Class -----------------------
class BitVectorIterator: #(IT1)
def __init__( self, bitvec ): #(IT2)
self.items = [] #(IT3)
for i in range( bitvec.size ): #(IT4)
self.items.append( bitvec._getbit(i) ) #(IT5)
self.index = -1 #(IT6)
def __iter__( self ): #(IT7)
return self #(IT8)
def next( self ): #(IT9)
self.index += 1 #(IT10)
if self.index < len( self.items ): #(IT11)
return self.items[ self.index ] #(IT12)
else: #(IT13)
raise StopIteration #(IT14)
#------------------------ End of Class Definition -----------------------
#------------------------ Test Code Follows -----------------------
if __name__ == '__main__':
# Construct a bit vector of size 0
print "\nConstructing a bit vector of size 0:"
bv1 = BitVector( size = 0 )
print bv1 # no output
# Construct a bit vector of size 2:
print "\nConstructing a bit vector of size 2:"
bv2 = BitVector( size = 2 )
print bv2 # 00
# Joining two bit vectors:
print "\nOutput concatenation of two previous bit vectors:"
print bv1 + bv2 # 00
# Construct a bit vector with a tuple of bits:
print "\nThis is a bit vector from a tuple of bits:"
bv = BitVector( bitlist = (1, 0, 0, 1) )
print bv # 1001
# Construct a bit vector with a list of bits:
print "\nThis is a bit vector from a list of bits:"
bv = BitVector( bitlist = [1, 1, 0, 1] )
print bv # 1101
# Construct a bit vector from an integer
bv = BitVector( intVal = 5678 )
print "\nBit vector constructed from integer 5678:"
print bv # 1011000101110
print "\nBit vector constructed from integer 0:"
bv = BitVector( intVal = 0 )
print bv # 0
print "\nBit vector constructed from integer 2:"
bv = BitVector( intVal = 2 )
print bv # 10
print "\nBit vector constructed from integer 3:"
bv = BitVector( intVal = 3 )
print bv # 11
print "\nBit vector constructed from integer 123456:"
bv = BitVector( intVal = 123456 )
print bv # 11110001001000000
print "\nInt value of the previous bit vector as computed by intVal():"
print bv.intValue() # 123456
print "\nInt value of the previous bit vector as computed by int():"
print int( bv ) # 123456
# Construct a bit vector directly from a file-like object:
import StringIO
x = "111100001111"
fp_read = StringIO.StringIO( x )
bv = BitVector( fp = fp_read )
print "\nBit vector constructed directed from a file like object:"
print bv # 111100001111
# Construct a bit vector directly from a bit string:
bv = BitVector( bitstring = '00110011' )
print "\nBit Vector constructed directly from a string:"
print bv # 00110011
bv = BitVector( bitstring = '' )
print "\nBit Vector constructed directly from an empty string:"
print bv # nothing
print "\nInteger value of the previous bit vector:"
print bv.intValue() # 0
# Test array-like indexing for a bit vector:
bv = BitVector( bitstring = '110001' )
print "\nPrints out bits individually from bitstring 110001:"
print bv[0], bv[1], bv[2], bv[3], bv[4], bv[5] # 1 1 0 0 0 1
print "\nSame as above but using negative array indexing:"
print bv[-1], bv[-2], bv[-3], bv[-4], bv[-5], bv[-6] # 1 0 0 0 1 1
# Test setting bit values with positive and negative
# accessors:
bv = BitVector( bitstring = '1111' )
print "\nBitstring for 1111:"
print bv # 1111
print "\nReset individual bits of above vector:"
bv[0]=0;bv[1]=0;bv[2]=0;bv[3]=0
print bv # 0000
print "\nDo the same as above with negative indices:"
bv[-1]=1;bv[-2]=1;bv[-4]=1
print bv # 1011
print "\nCheck equality and inequality ops:"
bv1 = BitVector( bitstring = '00110011' )
bv2 = BitVector( bitlist = [0,0,1,1,0,0,1,1] )
print bv1 == bv2 # True
print bv1 != bv2 # False
print bv1 < bv2 # False
print bv1 <= bv2 # True
bv3 = BitVector( intVal = 5678 )
print bv3.intValue() # 5678
print bv3 # 10110000101110
print bv1 == bv3 # False
print bv3 > bv1 # True
print bv3 >= bv1 # True
# Create a string representation of a bit vector:
fp_write = StringIO.StringIO()
bv.write_bits_to_fileobject( fp_write )
print "\nGet bit vector written out to a file-like object:"
print fp_write.getvalue() # 1011
print "\nExperiments with bitwise logical operations:"
bv3 = bv1 | bv2
print bv3 # 00110011
bv3 = bv1 & bv2
print bv3 # 00110011
bv3 = bv1 + bv2
print bv3 # 0011001100110011
bv4 = BitVector( size = 3 )
print bv4 # 000
bv5 = bv3 + bv4
print bv5 # 0011001100110011000
bv6 = ~bv5
print bv6 # 1100110011001100111
bv7 = bv5 & bv6
print bv7 # 0000000000000000000
bv7 = bv5 | bv6
print bv7 # 1111111111111111111
print "\nTry logical operations on bit vectors of different sizes:"
print BitVector( intVal = 6 ) ^ BitVector( intVal = 13 ) # 1011
print BitVector( intVal = 6 ) & BitVector( intVal = 13 ) # 0100
print BitVector( intVal = 6 ) | BitVector( intVal = 13 ) # 1111
print BitVector( intVal = 1 ) ^ BitVector( intVal = 13 ) # 1100
print BitVector( intVal = 1 ) & BitVector( intVal = 13 ) # 0001
print BitVector( intVal = 1 ) | BitVector( intVal = 13 ) # 1101
print "\nExperiments with setbit() and getsize():"
bv7[7] = 0
print bv7 # 1111111011111111111
print len( bv7 ) # 19
bv8 = (bv5 & bv6) ^ bv7
print bv8 # 1111111011111111111
print "\nConstruct a bit vector from what is in the file testinput1.txt:"
bv = BitVector( filename = 'TestBitVector/testinput1.txt' )
#print bv # nothing to show
bv1 = bv.read_bits_from_file(64)
print "\nPrint out the first 64 bits read from the file:"
print bv1
# 0100000100100000011010000111010101101110011001110111001001111001
print "\nRead the next 64 bits from the same file:"
bv2 = bv.read_bits_from_file(64)
print bv2
# 0010000001100010011100100110111101110111011011100010000001100110
print "\nTake xor of the previous two bit vectors:"
bv3 = bv1 ^ (bv2)
print bv3
# 0110000101000010000110100001101000011001000010010101001000011111
print "\nExperiment with dividing an even-sized vector into two:"
[bv4, bv5] = bv3.divide_into_two()
print bv4 # 01100001010000100001101000011010
print bv5 # 00011001000010010101001000011111
# Permute a bit vector:
print "\nWe will use this bit vector for experiments with permute()"
bv1 = BitVector( bitlist = [1, 0, 0, 1, 1, 0, 1] )
print bv1 # 1001101
bv2 = bv1.permute( [6, 2, 0, 1] )
print "\nPermuted and contracted form of the previous bit vector:"
print bv2 # 1010
print "\nExperiment with writing an internally generated bit vector out to a disk file:"
bv1 = BitVector( bitstring = '00001010' )
FILEOUT = open( 'TestBitVector/test.txt', 'wb' )
bv1.write_to_file( FILEOUT )
FILEOUT.close()
bv2 = BitVector( filename = 'TestBitVector/test.txt' )
bv3 = bv2.read_bits_from_file( 32 )
print "\nDisplay bit vectors written out to file and read back from the file and their respective lengths:"
print bv1, bv3
print len(bv1), len(bv3)
print "\nExperiments with reading a file from the beginning to end:"
bv = BitVector( filename = 'TestBitVector/testinput4.txt' )
print "\nHere are all the bits read from the file:"
while (bv.more_to_read):
bv_read = bv.read_bits_from_file( 64 )
print bv_read
print
print "\nExperiment with closing a file object and start extracting bit vectors from the file from the beginning again:"
bv.close_file_object()
bv = BitVector( filename = 'TestBitVector/testinput4.txt' )
bv1 = bv.read_bits_from_file(64)
print "\nHere are all the first 64 bits read from the file again after the file object was closed and opened again:"
print bv1
FILEOUT = open( 'TestBitVector/testinput5.txt', 'wb' )
bv1.write_to_file( FILEOUT )
FILEOUT.close()
print "\nExperiment in 64-bit permutation and unpermutation of the previous 64-bit bitvector:"
print "The permutation array was generated separately by the Fisher-Yates shuffle algorithm:"
bv2 = bv1.permute( [22, 47, 33, 36, 18, 6, 32, 29, 54, 62, 4,
9, 42, 39, 45, 59, 8, 50, 35, 20, 25, 49,
15, 61, 55, 60, 0, 14, 38, 40, 23, 17, 41,
10, 57, 12, 30, 3, 52, 11, 26, 43, 21, 13,
58, 37, 48, 28, 1, 63, 2, 31, 53, 56, 44, 24,
51, 19, 7, 5, 34, 27, 16, 46] )
print "Permuted bit vector:"
print bv2
bv3 = bv2.unpermute( [22, 47, 33, 36, 18, 6, 32, 29, 54, 62, 4,
9, 42, 39, 45, 59, 8, 50, 35, 20, 25, 49,
15, 61, 55, 60, 0, 14, 38, 40, 23, 17, 41,
10, 57, 12, 30, 3, 52, 11, 26, 43, 21, 13,
58, 37, 48, 28, 1, 63, 2, 31, 53, 56, 44, 24,
51, 19, 7, 5, 34, 27, 16, 46] )
print "Unpurmute the bit vector:"
print bv3
print
print
print "\nTry circular shifts to the left and to the right for the following bit vector:"
print bv3 # 0100000100100000011010000111010101101110011001110111001001111001
print "\nCircular shift to the left by 7 positions:"
bv3 << 7
print bv3 # 1001000000110100001110101011011100110011101110010011110010100000
print "\nCircular shift to the right by 7 positions:"
bv3 >> 7
print bv3 # 0100000100100000011010000111010101101110011001110111001001111001
print "Test len() on the above bit vector:"
print len( bv3 ) # 64
print "\nTest forming a [5:22] slice of the above bit vector:"
bv4 = bv3[5:22]
print bv4 # 00100100000011010
print "\nTest the iterator:"
for bit in bv4:
print bit, # 0 0 1 0 0 1 0 0 0 0 0 0 1 1 0 1 0
print
print "\nDemonstrate padding a bit vector from left:"
bv = BitVector( bitstring = '101010' )
bv.pad_from_left( 4 )
print bv # 0000101010
print "\nDemonstrate padding a bit vector from right:"
bv.pad_from_right( 4 )
print bv # 00001010100000
print "\nTest the syntax 'if bit_vector_1 in bit_vector_2' syntax:"
try:
bv1 = BitVector( bitstring = '0011001100' )
bv2 = BitVector( bitstring = '110011' )
if bv2 in bv1:
print "%s is in %s" % (bv2, bv1)
else:
print "%s is not in %s" % (bv2, bv1)
except ValueError, arg:
print "Error Message: " + str(arg)
print "\nTest the size modifier when a bit vector is initialized with the intVal method:"
bv = BitVector( intVal = 45, size = 16 )
print bv # 0000000000101101
bv = BitVector( intVal = 0, size = 8 )
print bv # 00000000
bv = BitVector( intVal = 1, size = 8 )
print bv # 00000001
print "\nTesting slice assignment:"
bv1 = BitVector( size = 25 )
print "bv1= ", bv1 # 0000000000000000000000000
bv2 = BitVector( bitstring = '1010001' )
print "bv2= ", bv2 # 1010001
bv1[6:9] = bv2[0:3]
print "bv1= ", bv1 # 0000001010000000000000000
print "\nTesting reset function:"
bv1.reset( 1 )
print "bv1= ", bv1 # 1111111111111111111111111
print bv1[3:9].reset(0) # 000000
print bv1[:].reset(0) # 0000000000000000000000000
print "\nTesting count_bit():"
bv = BitVector( intVal = 45, size = 16 )
y = bv.count_bits()
print y
bv = BitVector( bitstring = '100111' )
print bv.count_bits()
bv = BitVector( bitstring = '00111000' )
print bv.count_bits()
bv = BitVector( bitstring = '001' )
print bv.count_bits()
bv = BitVector( bitstring = '00000000000000' )
print bv.count_bits()
print "\nTest setValue idea:"
bv = BitVector( intVal = 7, size =16 )
print bv # 0000000000000111
bv.setValue( intVal = 45 )
print bv # 101101
print "\nTesting count_bits_sparse():"
bv = BitVector( size = 2000000 )
bv[345234] = 1
bv[233]=1
bv[243]=1
bv[18]=1
bv[785] =1
print "The number of bits set: ", bv.count_bits_sparse() # 5
print "\nTesting Jaccard similarity and distance and Hamming distance:"
bv1 = BitVector( bitstring = '11111111' )
bv2 = BitVector( bitstring = '00101011' )
print "Jaccard similarity: ", bv1.jaccard_similarity( bv2 ) # 0.5
print "Jaccard distance: ", bv1.jaccard_distance( bv2 ) # 0.5
print "Jaccard distance: ", bv1.hamming_distance( bv2 ) # 4
print "\nTesting next_set_bit():"
bv = BitVector( bitstring = '00000000000001' )
print bv.next_set_bit( 5 ) # 13
print "\nTesting rank_of_bit_set_at_index():"
bv = BitVector( bitstring = '01010101011100' )
print bv.rank_of_bit_set_at_index( 10 ) # 6
print "\nTesting isPowerOf2():"
bv = BitVector( bitstring = '10000000001110' )
print "int value: ", int( bv ) # 826
print bv.isPowerOf2() # False
print "\nTesting isPowerOf2_sparse():"
print bv.isPowerOf2_sparse() # False
print "\nTesting reverse():"
bv = BitVector( bitstring = '0001100000000000001' )
print "original bv: ", bv # 0001100000000000001
print "reversed bv: ", bv.reverse() # 1000000000000011000
print "\nTesting Greatest Common Divisor (gcd):"
bv1 = BitVector( bitstring = '01100110' )
print "first arg bv: ", bv1, " of int value: ", int(bv1) # 102
bv2 = BitVector( bitstring = '011010' )
print "second arg bv: ", bv2, " of int value: ", int(bv2) # 26
bv = bv1.gcd( bv2 )
print "gcd is: ", bv, " of int value: ", int(bv) # 2
print "\nTesting multiplicative_inverse:"
bv_modulus = BitVector( intVal = 32 )
print "modulus is bv: ", bv_modulus, " of int value: ", int(bv_modulus)
bv = BitVector( intVal = 17 )
print "bv: ", bv, " of int value: ", int(bv)
result = bv.multiplicative_inverse( bv_modulus )
if result is not None:
print "MI is: ", result, " of int value: ", int(result)
else: print "No multiplicative inverse in this case"