def parse_sparse6(string):
"""Read an undirected graph in sparse6 format from string.
Parameters
----------
string : string
Data in sparse6 format
Returns
-------
G : Graph
Raises
------
NetworkXError
If the string is unable to be parsed in sparse6 format
Examples
--------
>>> G = nx.parse_sparse6(':A_')
>>> sorted(G.edges())
[(0, 1), (0, 1), (0, 1)]
See Also
--------
generate_sparse6, read_sparse6, write_sparse6
References
----------
Sparse6 specification: http://cs.anu.edu.au/~bdm/data/formats.txt
"""
if string.startswith('>>sparse6<<'):
string = string[11:]
if not string.startswith(':'):
raise NetworkXError('Expected leading colon in sparse6')
n, data = data_to_n(graph6_to_data(string[1:]))
k = 1
while 1 << k < n:
k += 1
def parseData():
"""Return stream of pairs b[i], x[i] for sparse6 format."""
chunks = iter(data)
d = None # partial data word
dLen = 0 # how many unparsed bits are left in d
while 1:
if dLen < 1:
d = next(chunks)
dLen = 6
dLen -= 1
b = (d >> dLen) & 1 # grab top remaining bit
x = d & ((1 << dLen) - 1) # partially built up value of x
xLen = dLen # how many bits included so far in x
while xLen < k: # now grab full chunks until we have enough
d = next(chunks)
dLen = 6
x = (x << 6) + d
xLen += 6
x = (x >> (xLen - k)) # shift back the extra bits
dLen = xLen - k
yield b, x
v = 0
G = nx.MultiGraph()
G.add_nodes_from(range(n))
multigraph = False
for b, x in parseData():
if b == 1:
v += 1
# padding with ones can cause overlarge number here
if x >= n or v >= n:
break
elif x > v:
v = x
else:
if G.has_edge(x, v):
multigraph = True
G.add_edge(x, v)
if not multigraph:
G = nx.Graph(G)
return G
def test_n_data_n_conversion(self):
for i in [0, 1, 42, 62, 63, 64, 258047, 258048, 7744773, 68719476735]:
assert_equal(g6.data_to_n(g6.n_to_data(i))[0], i)
assert_equal(g6.data_to_n(g6.n_to_data(i))[1], [])
assert_equal(g6.data_to_n(g6.n_to_data(i) + [42, 43])[1], [42, 43])
def parse_sparse6(string):
"""Read an undirected graph in sparse6 format from string.
Parameters
----------
string : string
Data in sparse6 format
Returns
-------
G : Graph
Raises
------
NetworkXError
If the string is unable to be parsed in sparse6 format
Examples
--------
>>> G = nx.parse_sparse6(':A_')
>>> sorted(G.edges())
[(0, 1), (0, 1), (0, 1)]
See Also
--------
generate_sparse6, read_sparse6, write_sparse6
References
----------
Sparse6 specification: http://cs.anu.edu.au/~bdm/data/formats.txt
"""
if string.startswith('>>sparse6<<'):
string = string[11:]
if not string.startswith(':'):
raise NetworkXError('Expected leading colon in sparse6')
n, data = data_to_n(graph6_to_data(string[1:]))
k = 1
while 1<<k < n:
k += 1
def parseData():
"""Return stream of pairs b[i], x[i] for sparse6 format."""
chunks = iter(data)
d = None # partial data word
dLen = 0 # how many unparsed bits are left in d
while 1:
if dLen < 1:
d = next(chunks)
dLen = 6
dLen -= 1
b = (d>>dLen) & 1 # grab top remaining bit
x = d & ((1<<dLen)-1) # partially built up value of x
xLen = dLen # how many bits included so far in x
while xLen < k: # now grab full chunks until we have enough
d = next(chunks)
dLen = 6
x = (x<<6) + d
xLen += 6
x = (x >> (xLen - k)) # shift back the extra bits
dLen = xLen - k
yield b,x
v = 0
G = nx.MultiGraph()
G.add_nodes_from(range(n))
multigraph = False
for b,x in parseData():
if b == 1:
v += 1
# padding with ones can cause overlarge number here
if x >= n or v >= n:
break
elif x > v:
v = x
else:
if G.has_edge(x,v):
multigraph = True
G.add_edge(x,v)
if not multigraph:
G = nx.Graph(G)
return G
def test_n_data_n_conversion(self):
for i in [0, 1, 42, 62, 63, 64, 258047, 258048, 7744773, 68719476735]:
assert g6.data_to_n(g6.n_to_data(i))[0] == i
assert g6.data_to_n(g6.n_to_data(i))[1] == []
assert g6.data_to_n(g6.n_to_data(i) + [42, 43])[1] == [42, 43]
def test_n_data_n_conversion(self):
for i in [0, 1, 42, 62, 63, 64, 258047, 258048, 7744773, 68719476735]:
assert_equal(g6.data_to_n(g6.n_to_data(i))[0], i)
assert_equal(g6.data_to_n(g6.n_to_data(i))[1], [])
assert_equal(g6.data_to_n(g6.n_to_data(i) + [42, 43])[1],
[42, 43])