def decode_sets(bytes):
"""
Decodes a set of sets encoded using encode_sets (see above).
>>> b = BitStream(hex='0x00000000000000010503').tobytes(); write_sets(decode_sets(b))
'{{0,2},{0,1}}'
>>> b = BitStream(hex='0x000000000000000100').tobytes(); write_sets(decode_sets(b))
'{{}}'
>>> b = BitStream(hex='0x0000000000000001').tobytes(); write_sets(decode_sets(b))
'{}'
"""
from bitstring.bitstream import BitStream, pack
bs = BitStream(bytes=bytes)
bytesperset, content = bs.readlist('uint:64, bits')
setOfSets = set()
for bits in content.cut(bytesperset * 8):
aSet = set()
bits.reverse()
for i, b in enumerate(bits):
if b is True:
aSet.add(i)
setOfSets.add(frozenset(aSet))
return setOfSets
def decode_sets(bytes):
"""
Decodes a set of sets encoded using encode_sets (see above).
>>> b = BitStream(hex='0x00000000000000010503').tobytes(); write_sets(decode_sets(b))
'{{0,2},{0,1}}'
>>> b = BitStream(hex='0x000000000000000100').tobytes(); write_sets(decode_sets(b))
'{{}}'
>>> b = BitStream(hex='0x0000000000000001').tobytes(); write_sets(decode_sets(b))
'{}'
"""
from bitstring.bitstream import BitStream, pack
bs = BitStream(bytes=bytes)
bytesperset, content = bs.readlist('uint:64, bits')
setOfSets = set()
for bits in content.cut(bytesperset*8):
aSet = set()
bits.reverse()
for i,b in enumerate(bits):
if b is True:
aSet.add(i)
setOfSets.add(frozenset(aSet))
return setOfSets
def encode_sets(setOfSets):
"""
Encode a set of sets (e.g., a set of conflict sets or a set of hitting sets) in a binary format, where each
of the sets is represented as a word whose bits indicate which elements are part of the set.
The first 64bit unsigned big-endian integer indicates the number of bytes used per set.
For example, the set of sets {{a,c},{a,b}} contains three components: [a, b, c].
As we only use full bytes (i.e. 8 bits, 16 bits, ...), we use 1 byte to encode each set in this example.
Therefore, the first 64 bit of the encoded value are 0x0000000000000001.
The set {a,c} contains components number 1 and 3:
a = 0b001
c = 0b100
---------
= 0b101 = 0x5 = 0x05
The set {a,b} contains components number 1 and 2:
a = 0b001
b = 0b010
---------
= 0b011 = 0x3 = 0x03
Thus, the encoded value of {{a,c},{a,b}} is 0x00000000000000010503.
Examples:
>>> b = encode_sets(read_sets('{{a,c},{a,b}}')); BitStream(bytes=b).hex
'0x00000000000000010503'
>>> b = encode_sets(read_sets('{{0,2},{0,1}}')); BitStream(bytes=b).hex
'0x00000000000000010503'
Corner case: setOfSets contains just one empty set:
>>> b = encode_sets(frozenset([frozenset([])])); BitStream(bytes=b).hex
'0x000000000000000100'
Corner case: setOfSets is empty itself:
>>> b = encode_sets(frozenset([])); BitStream(bytes=b).hex
'0x0000000000000001'
"""
from bitstring.bitstream import BitStream, pack
comp = sorted(list(set().union(*setOfSets)))
bytesperset = max(1, int(ceil(float(len(comp)) / 8)))
bs = BitStream()
bs.append(pack('uint:64', bytesperset))
for aSet in setOfSets:
result = 0
for element in aSet:
result |= 2**(comp.index(element))
bs.append(pack('uint:%d' % (bytesperset * 8), result))
return bs.tobytes()
def encode_sets(setOfSets):
"""
Encode a set of sets (e.g., a set of conflict sets or a set of hitting sets) in a binary format, where each
of the sets is represented as a word whose bits indicate which elements are part of the set.
The first 64bit unsigned big-endian integer indicates the number of bytes used per set.
For example, the set of sets {{a,c},{a,b}} contains three components: [a, b, c].
As we only use full bytes (i.e. 8 bits, 16 bits, ...), we use 1 byte to encode each set in this example.
Therefore, the first 64 bit of the encoded value are 0x0000000000000001.
The set {a,c} contains components number 1 and 3:
a = 0b001
c = 0b100
---------
= 0b101 = 0x5 = 0x05
The set {a,b} contains components number 1 and 2:
a = 0b001
b = 0b010
---------
= 0b011 = 0x3 = 0x03
Thus, the encoded value of {{a,c},{a,b}} is 0x00000000000000010503.
Examples:
>>> b = encode_sets(read_sets('{{a,c},{a,b}}')); BitStream(bytes=b).hex
'0x00000000000000010503'
>>> b = encode_sets(read_sets('{{0,2},{0,1}}')); BitStream(bytes=b).hex
'0x00000000000000010503'
Corner case: setOfSets contains just one empty set:
>>> b = encode_sets(frozenset([frozenset([])])); BitStream(bytes=b).hex
'0x000000000000000100'
Corner case: setOfSets is empty itself:
>>> b = encode_sets(frozenset([])); BitStream(bytes=b).hex
'0x0000000000000001'
"""
from bitstring.bitstream import BitStream, pack
comp = sorted(list(set().union(*setOfSets)))
bytesperset = max(1,int(ceil(float(len(comp))/8)))
bs = BitStream()
bs.append(pack('uint:64', bytesperset))
for aSet in setOfSets:
result = 0
for element in aSet:
result |= 2**(comp.index(element))
bs.append(pack('uint:%d' % (bytesperset*8), result))
return bs.tobytes()