"""
Some utility functions.
Miscellaneous utilities
* list2set
* first
* uniq
* more_than
Term characterisation and generation
* to_term
* from_n3
Date/time utilities
* date_time
* parse_date_time
Statement and component type checkers
* check_context
* check_subject
* check_predicate
* check_object
* check_statement
* check_pattern
"""
from calendar import timegm
from time import altzone
# from time import daylight
from time import gmtime
from time import localtime
from time import time
from time import timezone
from os.path import splitext
from StringIO import StringIO
from rdflib.exceptions import ContextTypeError
from rdflib.exceptions import ObjectTypeError
from rdflib.exceptions import PredicateTypeError
from rdflib.exceptions import SubjectTypeError
from rdflib.graph import Graph
from rdflib.graph import QuotedGraph
from rdflib.namespace import Namespace
from rdflib.namespace import NamespaceManager
from rdflib.term import BNode
from rdflib.term import Literal
from rdflib.term import URIRef
from rdflib.py3compat import sign
__all__ = [
'list2set', 'first', 'uniq', 'more_than', 'to_term', 'from_n3',
'date_time', 'parse_date_time', 'check_context', 'check_subject',
'check_predicate', 'check_object', 'check_statement', 'check_pattern',
'guess_format', 'find_roots', 'get_tree']
[docs]def list2set(seq):
"""
Return a new list without duplicates.
Preserves the order, unlike set(seq)
"""
seen = set()
return [x for x in seq if x not in seen and not seen.add(x)]
[docs]def first(seq):
"""
return the first element in a python sequence
for graphs, use graph.value instead
"""
for result in seq:
return result
return None
[docs]def uniq(sequence, strip=0):
"""removes duplicate strings from the sequence."""
if strip:
return set(s.strip() for s in sequence)
else:
return set(sequence)
[docs]def more_than(sequence, number):
"Returns 1 if sequence has more items than number and 0 if not."
i = 0
for item in sequence:
i += 1
if i > number:
return 1
return 0
[docs]def to_term(s, default=None):
"""
Creates and returns an Identifier of type corresponding
to the pattern of the given positional argument string ``s``:
'' returns the ``default`` keyword argument value or ``None``
'<s>' returns ``URIRef(s)`` (i.e. without angle brackets)
'"s"' returns ``Literal(s)`` (i.e. without doublequotes)
'_s' returns ``BNode(s)`` (i.e. without leading underscore)
"""
if not s:
return default
elif s.startswith("<") and s.endswith(">"):
return URIRef(s[1:-1])
elif s.startswith('"') and s.endswith('"'):
return Literal(s[1:-1])
elif s.startswith("_"):
return BNode(s)
else:
msg = "Unrecognised term syntax: '%s'" % s
raise Exception(msg)
[docs]def from_n3(s, default=None, backend=None, nsm=None):
r'''
Creates the Identifier corresponding to the given n3 string.
>>> from_n3('<http://ex.com/foo>') == URIRef('http://ex.com/foo')
True
>>> from_n3('"foo"@de') == Literal('foo', lang='de')
True
>>> from_n3('"""multi\nline\nstring"""@en') == Literal(
... 'multi\nline\nstring', lang='en')
True
>>> from_n3('42') == Literal(42)
True
>>> from_n3(Literal(42).n3()) == Literal(42)
True
>>> from_n3('"42"^^xsd:integer') == Literal(42)
True
>>> from rdflib import RDFS
>>> from_n3('rdfs:label') == RDFS['label']
True
>>> nsm = NamespaceManager(Graph())
>>> nsm.bind('dbpedia', 'http://dbpedia.org/resource/')
>>> berlin = URIRef('http://dbpedia.org/resource/Berlin')
>>> from_n3('dbpedia:Berlin', nsm=nsm) == berlin
True
'''
if not s:
return default
if s.startswith('<'):
return URIRef(s[1:-1])
elif s.startswith('"'):
if s.startswith('"""'):
quotes = '"""'
else:
quotes = '"'
value, rest = s.rsplit(quotes, 1)
value = value[len(quotes):] # strip leading quotes
datatype = None
language = None
# as a given datatype overrules lang-tag check for it first
dtoffset = rest.rfind('^^')
if dtoffset >= 0:
# found a datatype
# datatype has to come after lang-tag so ignore everything before
# see: http://www.w3.org/TR/2011/WD-turtle-20110809/
# #prod-turtle2-RDFLiteral
datatype = from_n3(rest[dtoffset + 2:], default, backend, nsm)
else:
if rest.startswith("@"):
language = rest[1:] # strip leading at sign
value = value.replace(r'\"', '"')
# Hack: this should correctly handle strings with either native unicode
# characters, or \u1234 unicode escapes.
value = value.encode("raw-unicode-escape").decode("unicode-escape")
return Literal(value, language, datatype)
elif s == 'true' or s == 'false':
return Literal(s == 'true')
elif s.isdigit():
return Literal(int(s))
elif s.startswith('{'):
identifier = from_n3(s[1:-1])
return QuotedGraph(backend, identifier)
elif s.startswith('['):
identifier = from_n3(s[1:-1])
return Graph(backend, identifier)
elif s.startswith("_:"):
return BNode(s[2:])
elif ':' in s:
if nsm is None:
# instantiate default NamespaceManager and rely on its defaults
nsm = NamespaceManager(Graph())
prefix, last_part = s.split(':', 1)
ns = dict(nsm.namespaces())[prefix]
return Namespace(ns)[last_part]
else:
return BNode(s)
[docs]def check_context(c):
if not (isinstance(c, URIRef) or
isinstance(c, BNode)):
raise ContextTypeError("%s:%s" % (c, type(c)))
[docs]def check_subject(s):
""" Test that s is a valid subject identifier."""
if not (isinstance(s, URIRef) or isinstance(s, BNode)):
raise SubjectTypeError(s)
[docs]def check_predicate(p):
""" Test that p is a valid predicate identifier."""
if not isinstance(p, URIRef):
raise PredicateTypeError(p)
[docs]def check_object(o):
""" Test that o is a valid object identifier."""
if not (isinstance(o, URIRef) or
isinstance(o, Literal) or
isinstance(o, BNode)):
raise ObjectTypeError(o)
[docs]def check_statement(triple):
(s, p, o) = triple
if not (isinstance(s, URIRef) or isinstance(s, BNode)):
raise SubjectTypeError(s)
if not isinstance(p, URIRef):
raise PredicateTypeError(p)
if not (isinstance(o, URIRef) or
isinstance(o, Literal) or
isinstance(o, BNode)):
raise ObjectTypeError(o)
[docs]def check_pattern(triple):
(s, p, o) = triple
if s and not (isinstance(s, URIRef) or isinstance(s, BNode)):
raise SubjectTypeError(s)
if p and not isinstance(p, URIRef):
raise PredicateTypeError(p)
if o and not (isinstance(o, URIRef) or
isinstance(o, Literal) or
isinstance(o, BNode)):
raise ObjectTypeError(o)
[docs]def date_time(t=None, local_time_zone=False):
"""http://www.w3.org/TR/NOTE-datetime ex: 1997-07-16T19:20:30Z
>>> date_time(1126482850)
'2005-09-11T23:54:10Z'
@@ this will change depending on where it is run
#>>> date_time(1126482850, local_time_zone=True)
#'2005-09-11T19:54:10-04:00'
>>> date_time(1)
'1970-01-01T00:00:01Z'
>>> date_time(0)
'1970-01-01T00:00:00Z'
"""
if t is None:
t = time()
if local_time_zone:
time_tuple = localtime(t)
if time_tuple[8]:
tz_mins = altzone // 60
else:
tz_mins = timezone // 60
tzd = "-%02d:%02d" % (tz_mins // 60, tz_mins % 60)
else:
time_tuple = gmtime(t)
tzd = "Z"
year, month, day, hh, mm, ss, wd, y, z = time_tuple
s = "%0004d-%02d-%02dT%02d:%02d:%02d%s" % (
year, month, day, hh, mm, ss, tzd)
return s
[docs]def parse_date_time(val):
"""always returns seconds in UTC
# tests are written like this to make any errors easier to understand
>>> parse_date_time('2005-09-11T23:54:10Z') - 1126482850.0
0.0
>>> parse_date_time('2005-09-11T16:54:10-07:00') - 1126482850.0
0.0
>>> parse_date_time('1970-01-01T00:00:01Z') - 1.0
0.0
>>> parse_date_time('1970-01-01T00:00:00Z') - 0.0
0.0
>>> parse_date_time("2005-09-05T10:42:00") - 1125916920.0
0.0
"""
if "T" not in val:
val += "T00:00:00Z"
ymd, time = val.split("T")
hms, tz_str = time[0:8], time[8:]
if not tz_str or tz_str == "Z":
time = time[:-1]
tz_offset = 0
else:
signed_hrs = int(tz_str[:3])
mins = int(tz_str[4:6])
secs = (sign(signed_hrs) * mins + signed_hrs * 60) * 60
tz_offset = -secs
year, month, day = ymd.split("-")
hour, minute, second = hms.split(":")
t = timegm((int(year), int(month), int(day), int(hour),
int(minute), int(second), 0, 0, 0))
t = t + tz_offset
return t
SUFFIX_FORMAT_MAP = {
'rdf': 'xml',
'rdfs': 'xml',
'owl': 'xml',
'n3': 'n3',
'ttl': 'turtle',
'nt': 'nt',
'trix': 'trix',
'xhtml': 'rdfa',
'html': 'rdfa',
'svg': 'rdfa',
'nq': 'nquads',
'trig': 'trig'
}
def _get_ext(fpath, lower=True):
"""
Gets the file extension from a file(path); stripped of leading '.' and in
lower case. Examples:
>>> _get_ext("path/to/file.txt")
'txt'
>>> _get_ext("OTHER.PDF")
'pdf'
>>> _get_ext("noext")
''
>>> _get_ext(".rdf")
'rdf'
"""
ext = splitext(fpath)[-1]
if ext == '' and fpath.startswith("."):
ext = fpath
if lower:
ext = ext.lower()
if ext.startswith('.'):
ext = ext[1:]
return ext
[docs]def find_roots(graph, prop, roots=None):
"""
Find the roots in some sort of transitive hierarchy.
find_roots(graph, rdflib.RDFS.subClassOf)
will return a set of all roots of the sub-class hierarchy
Assumes triple of the form (child, prop, parent), i.e. the direction of
RDFS.subClassOf or SKOS.broader
"""
non_roots = set()
if roots is None:
roots = set()
for x, y in graph.subject_objects(prop):
non_roots.add(x)
if x in roots:
roots.remove(x)
if y not in non_roots:
roots.add(y)
return roots
[docs]def get_tree(graph,
root,
prop,
mapper=lambda x: x,
sortkey=None,
done=None,
dir='down'):
"""
Return a nested list/tuple structure representing the tree
built by the transitive property given, starting from the root given
i.e.
get_tree(graph,
rdflib.URIRef("http://xmlns.com/foaf/0.1/Person"),
rdflib.RDFS.subClassOf)
will return the structure for the subClassTree below person.
dir='down' assumes triple of the form (child, prop, parent),
i.e. the direction of RDFS.subClassOf or SKOS.broader
Any other dir traverses in the other direction
"""
if done is None:
done = set()
if root in done:
return
done.add(root)
tree = []
if dir == 'down':
branches = graph.subjects(prop, root)
else:
branches = graph.objects(root, prop)
for branch in branches:
t = get_tree(graph, branch, prop, mapper, sortkey, done, dir)
if t:
tree.append(t)
return (mapper(root), sorted(tree, key=sortkey))
def test():
import doctest
doctest.testmod()
if __name__ == "__main__":
# try to make the tests work outside of the time zone they were written in
# import os, time
# os.environ['TZ'] = 'US/Pacific'
# try:
# time.tzset()
# except AttributeError, e:
# print e
# pass
# tzset missing! see
# http://mail.python.org/pipermail/python-dev/2003-April/034480.html
test() # pragma: no cover
